Question regarding antenna bandwidth for coax vs: open wire line

[K9MB]

Hi Mike,

This spacing worked well in the past when I fed the loop driven element with RG-213 and then tuned the second loop as a reflector using the other RG-213 coax as a stub.  I am trying to achieve?  a bodacious low angle signal at about 25 degrees take off. 

In this case I wish to make identical loops that are each forced driven with equal length 150' RG-11, hopefully to a 75 ohm 1:1 match for each loop..   One of these  equal length coaxes  will get a 90 degree (or whatever is needed) phasing coax to make a unidirectional beam pattern into Eu.  Switch the phasing coax to switch directions. (USA)

So, I want to initially tune the loops each to 3790 by just trimming the loop's wire length. Once I get 3790 for each, the coaxes get attached.

I need to know when I do the initial tuning do I tune each loop alone or do I keep both loops in position (spaced 40' apart) and tune them that way, to take in account the mutual coupling detuning effects?

T

Ok, Tom. Sorry- my brain skipped a cog and I put the array on 40 meters. 🤪
Ok, you have about 0.15 wavelength spacing and I see how you made that work with a reflector.

I am curious, however, why you are not just making an array of phased verticals if you want a low angle signal. Seems like 4- 1/4 wave verticals can be phase shifted to give several cardioid directional patterns and with a good ground under it, the radiation angle will be down around 20 degrees, I am thinking.
Why are you not using phased verticals?
What is the height of the loops?

[K1JJ]

Hi Mike,

Been there, done that.  There was a time when I had an 18,000'  spool of  #5 copper clad aluminum wire. I went thru the whole spool trying every antenna known to man on 75M with a 150' tower. The bottom line is a high horizontal Yagi or loops are the clear winner.

My loops are at 190' high, average height about 130'.   They are by far the best antenna I've ever used on 75M for DX.    The verticals also have their problems. You need a very large, clear area clear of buildings, etc. The ground should be good as well as an elaborate radial field.  The phasing/switching  is complex unless you buy a ready-made system.  You need four verticals.  They can be noisy due to power line coupling vertically.   In general, the biggest signals on the 75M band DX-wise are high Yagis or loops that are 1/2 wavelength above ground.

So that's why I've stuck with the horizontally polarized loops on 75M for so long and want to get this same system working well again.

I received my ferrites today so ready to go.  I will take Norm's suggestion and tune each loop individually.  This way they will both be the same wire lengths, have the same length feedlines and resonate at 3790.  From the ground level I can then add force feeding or tuning a reflector with the coax and a capacitor.  Lots of options.


T

[K9MB]

Hi Mike,

Been there, done that.  There was a time when I had an 18,000'  spool of  #5 copper clad aluminum wire. I went thru the whole spool trying every antenna known to man on 75M with a 150' tower. The bottom line is a high horizontal Yagi or loops are the clear winner.

My loops are at 190' high, average height about 130'.   They are by far the best antenna I've ever used on 75M for DX.    The verticals also have their problems. You need a very large, clear area clear of buildings, etc. The ground should be good as well as an elaborate radial field.  The phasing/switching  is complex unless you buy a ready-made system.  You need four verticals.  They can be noisy due to power line coupling vertically.   In general, the biggest signals on the 75M band DX-wise are high Yagis or loops that are 1/2 wavelength above ground.

So that's why I've stuck with the horizontally polarized loops on 75M for so long and want to get this same system working well again.

I received my ferrites today so ready to go.  I will take Norm's suggestion and tune each loop individually.  This way they will both be the same wire lengths, have the same length feedlines and resonate at 3790.  From the ground level I can then add force feeding or tuning a reflector with the coax and a capacitor.  Lots of options.


T

Hi Tom,
Thanks for the rundown. I get it with the verticals requiring a lot of phasing control and of course a large ground shield is essential for the kund of performance you are wanting.
Just one more question, as a follow up in my height inquiry.
Have you ever considered vertical half waves suspended from a non conductive cable like dacron rope or phillystran and then feed them like a LPDA with open feeders.
At 150 feet at the top, the bottom of the vertical hals waves will be about 25 feet above the ground, but the takeoff angle should be very low because of the vertical orientation and ground losses will be less than a monopole above a poor ground screen.
I have toyed with this a little for 40 meters because I have only 80 feet to work with, but it is on a back burner.

I have been meaning to tell you about a wire beam array I built for 20 meters when I was young and poor that worked very well.

I built an extended double zepp for 20 meters and then I put a pair of reflectors behind the driven elements limed up with the outer half wave and a second pair of directors in front of the driven element - each about 0.2 wavelengths from the driven extended double zepp.
Then I fed it with 36 feet of OWL and shorted the end with a sliding short and then tapped up the line with a folded half wave coaxial balun.

I was using an old SBE33 that I rebuilt and a 4x807 GG amp (told you I was poor😉).  I was putting out 400 watts into that wire array and it beat local guys with 1000 watt amps in Florida where my Father-In Law lived and a guy from Venezuela called me one day after we completed our QSO and said I had a very strong signal in that country.
My pitiful array was very small potatoes to your 150 ft loops, but it was great experience in how old antennas can be adapted for new uses.
I actually got the idea from some 10 element 2 meter antennas that I got from Russ Farnsworth who is the inventor of the Farnsworth Method of teaching CW. He marketed his tapes theough Heathkit company.
Russ was blind, but he was amazing and he did a lot of work in spite of his disabilities. Sorry for the digression. It happens to old guys that they see something new that reminds them of something from the “old days” 😉
73, Mike

[K1JJ]

Hi Mike,

FB on your 20M collinear array with reflectors and directors. SBE 33 and quad 807s...      That's a coincidence cuz I built the same antenna, but a little larger back in the early 90s.  It was a stacked and collinear, 36 elements.  It had a narrow beam fixed on Eu.  That antenna sure talked. I had a 20M reference dipole at 30' high and the array was usually about 20 dB louder.  Describing it I used to say it was a curtain array 90' tall and 300' wide. I still have it rolled up and stored.  I'd like to build something smaller, like maybe  2 over  2, over 2, over 2  for 20M and feed it with openwire to show huge gain on 15/10M.  I modeled it out already and is enchanting.  Lazy H's stacked or whatever. Still thinking.

BTW, I did try a 75M TCI  LPDA design in the vertical plane. It was about 10 dB weaker than the high Yagis.  I figgered it was lack of ground screen.  

Today was a crazy day.  I got tired of watching it climb to 99 F and not going out to work.  Screw being a pussy. I went out at 12 noon, climbed up to 125' and climbed down at 3:30 PM at 98F. Finished rebuilding the feedline and feed junction for the triple 40M Yagis stack.  It was finished, finally!!   It took me two months of work to repair the middle Yagi aluminum damage and clean up the feedline contamination.  I measured each Yagi and found they were all within 20 KHz of each other. Nice.    With confidence I walked into the dog house to test the full array for the first time. I expected 1:1 swr.  It was 14:1!!!  NOOOOOOOO!!!!!!   I started to get depressed thinking of what would be required to take them down again.

After 30 minutes or so I went back and tried to figure out what was wrong. Did I make a wiring error?  Then I realized that I had the wrong cable plugged into the 50:75 ohm balun. I was measuring some old 6M cable from 10 years ago.  

I hooked it up properly and there was nothing!  Did my MFJ-259 crap out?  No, it was working. The swr was 1:1 at 7.150 for the stack. In fact the stack is more broad banded than my 40M wire dipoles. I think the fat aluminum full size elements all tied in parallel makes it so broad.  The reflectors are tuned for about 6.800 so the swr is near 1.2:1 from 7.0 all the way up to 7.3 MHz.   The f-b and gain drops off cuz the reflector is fixed.

I listened to the 40M band and see the W4s are weak off the back and the locals are weak due to being a low angle antenna at 13 degrees.  I tuned in a few Euro stations and the stack was always louder than on the 40M dipole at 105', as you'd expect.

So far, looks like the stack repair is going to work out FB. Gawd my feet are really sore from standing on the rails for 3 1/2 hours.

So tomorrow another climb -  but this time to hoist up the new RG-11 feedlines to the 75M delta loops. If I can get this done despite the hot sun, I'll be close to completing the antenna projects. The 20M plans will have to wait.  That 500' RG-11 roll was a great deal for $85.  It feeds the fan dipole and now the delta loops.  All gone.


T

[K9MB]

Hi Mike,

FB on your 20M collinear array with reflectors and directors. SBE 33 and quad 807s...      That's a coincidence cuz I built the same antenna, but a little larger back in the early 90s.  It was a stacked and collinear, 36 elements.  It had a narrow beam fixed on Eu.  That antenna sure talked. I had a 20M reference dipole at 30' high and the array was usually about 20 dB louder.  Describing it I used to say it was a curtain array 90' tall and 300' wide. I still have it rolled up and stored.  I'd like to build something smaller, like maybe 12 elements, 2 over  2, over 2, over 2  for 20M and feed it with openwire to show huge gain on 15/10M.  I modeled it out already and is enchanting.  Lazy H's stacked or whatever. Still thinking.

BTW, I did try a 75M TCI  LPDA design in the vertical plane. It was about 10 dB weaker than the high Yagis.  I figgered it was lack of ground screen.  

Today was a crazy day.  I got tired of watching it climb to 99 F and not going out to work.  Screw being a pussy. I went out at 12 noon, climbed up to 125' and climbed down at 3:30 PM at 98F. Finished rebuilding the feedline and feed junction for the triple 40M Yagis stack.  It was finished, finally!!   It took me two months of work to repair the middle Yagi aluminum damage and clean up the feedline contamination.  I measured each Yagi and found they were all within 20 KHz of each other. Nice.    With confidence I walked into the dog house to test the full array for the first time. I expected 1:1 swr.  It was 14:1!!!  NOOOOOOOO!!!!!!   I started to get depressed thinking of what would be required to take them down again.

After 30 minutes or so I went back and tried to figure out what was wrong. Did I make a wiring error?  Then I realized that I had the wrong cable plugged into the 50:75 ohm balun. I was measuring some old 6M cable from 10 years ago.  

I hooked it up properly and there was nothing!  Did my MFJ-259 crap out?  No, it was working. The swr was 1:1 at 7.150 for the stack. In fact the stack is more broad banded than my 40M wire dipoles. I think the fat aluminum elements all tied in parallel makes it so broad.  The reflector is tuned for about 6.800 so the swr is near 1.2:1 from 7.0 all the way up to 7.3 MHz.   The f-b and gain drops off cuz the reflector is fixed.

I listened to the 40M band and see the W4s are weak off the back and the locals are weak due to being a low angle antenna at 13 degrees.  I tuned in a few Euro stations and the stack was always louder than on the 40M dipole at 105', as you'd expect.

So far, looks like the stack repair is going to work out FB. Gawd my feet are really sore from standing on the rails for 3 1/2 hours.

So tomorrow another climb -  but this time to hoist up the new RG-11 feedlines to the 75M delta loops. If I can get this done despite the hot sun, I'll be close to completing the antenna projects. The 20M plans will have to wait.


T

Tom,
Thanks for the report on the vertical LPDA. They are indeed not known for forward gain or F-B compared to a good YAGI array. Your remotely tuned end fire array will allow the tweaking to optimize on the fly once you get the phasing figured out.

You have my deepest admiration for your grit, getting out in this Summer hell storm..😬
It has been decades since I was up over 100 feet on a tower and 10 years ago, I decided to stop because my back and knees made it too painful.
My pitiful array of 6 elements on 20 is not to be compared to that array you put up, but it was great fun, lacking only rotatability.
I am content with a Teledyne T8 at 65 feet now and am focused on 160-40 meters antennas.
I am ready to put up 80 feet of 25G on a home made insulated ball joint and will run 160 and 80 meter verticals- inverted Ls on it. I have been considering a skeleton disk-cone with 8 wires around the tower lately which should cover both bands.
My ground will be 7000 feet of PE insulated 14awg dog fence wire groundstapled down in a 100ft circle around the base. It is all aline on a little hilltop 300’ from my shack.
Nothing like your impressive arrays, but there is hope that I can work some DX when ole Sol calms down in a few years..😉

I have enough space for two 350’ short beverages crisscrossing to cover NE, E, SE, and SW directions.
I wish I had your energy, but at 74, I have slowed down and cannot do what you did today without an appearance in the Obits…😉😁
Thank you for the rundown.
Looking forward to further reports.
I like your results on the RG11, so I have decided to feed my 80 meter fan or cage
( not decided yet) with this lightweight cheap stuff. I have two 500’ spools, so it all seems possible.
I am considering that 3 ft spaced cage because I have exactly 130 feet between my two 45G towers. I have to mount it low at about 55 feet, so a fan would put the lower one down at 30’ at the ends. I will run some tight Dacron plus 10ga copperweld so I can support the middle with about 5-6ft of sag and the middle is right by my shack, so the feedline will be short and light.
It will be interesting to compare bandwidth. I suspect that your fan is better though..

73, Mike

[K1JJ]

Mike, FB on the PE insulated dog fence in a circle as a radial ground plane.  That sounds like a cool project with the big tower.


Here's some pics of the feedpoint RG-11 I made up today for the 75M delta loops.  Look closely and you will see the dacryon cord supporting the 12 ferrite beads. The beads will be supported by the center insulator later.  And I use a pipe hitch, like a hangman's noose, to support the coax itself.  The upper portion is where the connector resides and is quad sealed for weather.  I'm hoping this arrangement for the two loops is waterproof as well as strong to support the weight of the beads and coax.  The coax will be routed to the tower and tied to a tower leg all the way to the ground level. Maybe 40' of free hang.

T

Pic 1-3:  Notice how the beads and coax are independently supported, putting the least amount of strain on the RG-11 coax.   The RG-11 coax is not as rugged as RG-213 for strain, so needs extra precautions.   The weatherproofing uses four layers:  33 tape, rubber clay tape, 33 tape and then a layer of liquid tape.   I made my own RG-11 connectors using a 3/8" copper tubing sleeve and hose clamps.  Plenty of D-Ox.  The output leads are soldered to the sleeve and copper inner conductor.

[K1JJ]

Pic  2: It's so hot that I gave Yaz a hose spray down.  He actually enjoys it and runs back and forth thru the spray. Stops his panting right way.

Pic 3:  The 75M fan broadband dipoles are finished and in service. It's nice to put things to bed.

[K1JJ]

Pic 1:   The 40M stack is finally finished. Now testing - all work to be done on the ground.... YAY!  Look closely at the center Yagi to see the coax coil and connections finished yesterday.  I DO NOT want to climb up there again hopefully for a long time...    60', 125', 185'  fed in phase, fixed on Eu..

Pic 2:  This is my portable tower workbench - the back of the Dodge truck..  I drive it from tower to tower as needed. I just cleaned it but it can look like chaos personified after a job.  

[K9MB]

Pic  2: It's so hot that I gave Yaz a hose spray down.  He actually enjoys it and runs back and forth thru the spray. Stops his panting right way.

Pic 3:  The 75M fan broadband dipoles are finished and in service. It's nice to put things to bed.

Tom,
I chose these three images to make my comments, not a little because of that dignified and wise looking “Good Dog” you included. It is easy-in this photo to see why you talk about him all the time. Looking into those soulful eyes, one can see why we all love dogs, specially older ones mentioned as one of the three finest things in the world by Tom T Hall in his hit song-
Yaz actually looks like a younger dog, but he has that ageless look anyway.
https://youtu.be/pQAk-xYxvVo
I can see absolutely no way to improve on Yaz. He is the quintessential “Good Dog” we all love as a faithful companion… 😎😁

But on to antennas:

The packages look water tight and secure for the feedlines and  that Dacron braided line is extremely strong, resistant to UV and does not stretch like nylon.

My only question, is a question I ask when I see ferrite suspended in tue weather where it can meet with many challenges.

In those stacks, I wonder about water finding its way down the opening in tje top bead. My own compulsive nature would seal that top where the feedline emerges to prevent an easy entry for water.

Then at each joint, the joints are open and that probably is a good thing to allow any moisture that got in from being captured in there though my own compulsions would likely wrap them with scotch 33 or 88. Then the bottom where there is what looks a connector seems to be sealed off so any water in that space might not be able to get out.
If the bottom was mostly sealed and the top open and you started getting freezing rain, the prospect of a icicle forming in the stack seems possible.
Maybe I can ot see it properly, but I,would,be sure that entry from the top was very difficult and exit from the bottom emulates the old inverted bucket method for waterproofimg a lot of outdoor connections and preamps, etc…

Third- that is a nice pic of your Fan Dipole. That needs to be published more thoroughly, IMO with more details on dimensions and  some SWR plot pics, etc. that is a great “Every Ham’s Antenna for 80 meters and I think that your application of the 75 ohm lightweight CATV-Sat coax is key to making it supportable.

Nice work- specially you- Yaz and you are doing pretty well yourself, Tom with minor reservations visa vis my questions.😉😂😂😁
73, MB

[K1JJ]

Mike,

I'm really glad you caught that - and brought up the ferrite beads potential water/ice problem.  I was thinking that water wouldn't bother the cores but I didn't think about trapped ice in the wintertime.  

Yes, I will seal off the top, but not sure what you are recommending for the joints. There are a lot of them.   For the fan dipole I sealed off the whole ferrite stack, top side and bottom.  I could do the same thing with the loops.... or what if I seal the top, sides and leave the gap open at the bottom where the coax just fits loosely and leave that small gap for leakage or evaporation? Or should I seal everything off using the clay/tape  treatment, etc..?

Since I took the pictures I decided to double up on all the support cords. I wanted a balanced support, so there are now four cords per feedpoint. The cords are spread out so that there is less tendency to twist too.

So please think a little about what you feel is the best approach for the ferrite cores and I will modify them...

BTW, this is Yaz 4.  I've had an English Springer Spaniel since 21 years old. They usually live to about 14 years old when things work out well. He is five.  He goes canoeing, kayaking and hiking with me. I cannot imagine life without a dog. I'm crazy about dogs.
T

[K9MB]

Mike,

I'm really glad you caught that - and brought up the ferrite beads potential water/ice problem.  I was thinking that water wouldn't bother the cores but I didn't think about trapped ice in the wintertime.  

Yes, I will seal off the top, but not sure what you are recommending for the joints. There are a lot of them.   For the fan dipole I sealed off the whole ferrite stack, top side and bottom.  I could do the same thing with the loops.... or what if I seal the top, sides and leave the gap open at the bottom where the coax just fits loosely and leave that small gap for leakage or evaporation? Or should I seal everything off using the clay/tape  treatment, etc..?

Since I took the pictures I decided to double up on all the support cords. I wanted a balanced support, so there are now four cords per feedpoint. The cords are spread out so that there is less tendency to twist too.

So please think a little about what you feel is the best approach for the ferrite cores and I will modify them...

BTW, this is Yaz 4.  I've had an English Springer Spaniel since 21 years old. They usually live to about 14 years old when things work out well. He is five.  He goes canoeing, kayaking and hiking with me. I cannot imagine life without a dog. I'm crazy about dogs.
T

On dogs: I grew up with Cockers and Beagles and have always loved dogs myself.
Our faithful ole Pug died in 2016 and we have been dogless since but I have a cat that follows me around and even licks my leg sometimes. She seems to think she is a dog, but she will not allow anyone to pet her unless it is her idea while the ole Pug loved everybody, so dogs are great companions and friends.
I remembered when you lost your last Yaz in reading on the Forum. Sad to lose an old friend, but the best cure for that had to be young Yaz. He has obviously gained the wisdom of his 4 years and is a beautiful soul if a picture does not lie. 😎


But to business:
Well, the old wisdom is to either hermetically seal (glass metal or high quality potting material) or use the “inverted bucket” technology that has been around since Ancient Egypt or before.
The bucket method allows humidity and even a splash, but air flow allows it to dry out.
In this case, you need that top (bottom of inverted bucket) to shed all the water it can and then anything that gets inside must have a way for moisture to pass through and dry out.

After the seal is made between coax and the top of the stack, it gets more complicated, because of the necessity that any heat that is generated in the beads must be dissipated so the beads stay as far below the Curie temperature as possible. For #43 ferrite that is about 300 degrees F. At that temperature the feedline will be in much worse danger than the beads though.
Since you are only using a few beads, there is some potential that sufficient common mode current losses will heat them up an unknown amount.

It might be fine if they stay cool anyway.
I sealed some of these 1020-43 beads for my class E transmitter output transformer with a product from JB Weld that I really like. It is a polyurethane sealant.
I buttered each surface with the sealant and clamped them together for 24 hours.
Some people use tape at each joint like 3M #33 or #88 tape. Shrink tube is the best to weatherproof as long as the bottom is open and as long as they are mot heating up. I like the JB weld best. Amazing stuff that is really hard and the bond is amazing.
By the way, I ran a 1/2 rod through the beads to keep glue in tue seams. You can wrap a 1/2 wooden dowel with teflon tape or I have just used nylon tubing because it does not bond well to it.
EDIT LATER: I suspect that the JB Weld will be good in the weather and you can leave the beads out where they can radiate heat. MB


Another Idea:🤓 (EDIT LATER) There are a ton of wireless meat thermometers that seem to work on Bluetooth and some can interface with your phone. The thing that cannot be certain is whether the advertised range and accuracy is there, but it is still a compelling idea. MB

If you wanted to test for heating in real time,
Here is a possible device to get data on the heating effects within encapsulation.
It is a wireless thermometer that reads up to 200 degrees F and has an RF link that is claimed to reach 1/4 mile.
Cheap too! 😎 It might not work ,but worth a try to be able to remotely test the bead chokes with hundreds of watts on the line(s)
I have been thinking of getting one of these for my toroid baluns that are going in NEMA boxes that will have vents that will not allow water imside, but will have screens to allow moisture not to accumulate inside. Jim Brown says not to put them in a box, but it is eotjer that or pot them up because I hate water damage and have seen a lifetimes worth already…😉
73, Mike

https://www.amazon.com/dp/B08Z3XH313/ref=sspa_dk_detail_1?psc=1&pd_rd_i=B08Z3XH313&pd_rd_w=veibJ&content-id=amzn1.sym.3481f441-61ac-4028-9c1a-7f9ce8ec50c5&pf_rd_p=3481f441-61ac-4028-9c1a-7f9ce8ec50c5&pf_rd_r=76A6932TECQF5ZYR2BNX&pd_rd_wg=3pgln&pd_rd_r=44a7e94a-7e6f-4616-8e36-7e7ed093dc2c&s=home-garden&smid=A2E6L4XU587CP3&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzOVFXMzk3RzVKQ1I0JmVuY3J5cHRlZElkPUEwNjQ2OTU2MlBTMzdHQVZQMEkwVSZlbmNyeXB0ZWRBZElkPUEwMDQ3MjE5MUZZWlFOUU01VjlHTCZ3aWRnZXROYW1lPXNwX2RldGFpbF90aGVtYXRpYyZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

https://www.amazon.com/J-B-Weld-Plastic-Bonder-Syringe/dp/B0B5VJZ5XW/ref=sr_1_2_sspa?crid=18MKOMG7OGF79&keywords=jb+weld&qid=1658717388&sprefix=JB%2Caps%2C92&sr=8-2-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzN05UNEFDVlpLS045JmVuY3J5cHRlZElkPUEwMTE4MDk2WVA4MFAzQlUySTlIJmVuY3J5cHRlZEFkSWQ9QTAxMzU4NDEyUlZNQjZUN1I3MktYJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

[K1JJ]

Thanks for the great ideas and information, Mike!

I took it all into consideration and just finished up the mods.  I will take the simplest approach and Scotch 33 tape up all the bead joints.  I quad weatherproofed the top hole of the stacks.  I left the bottom hole open for ventilation.  I don't expect a lot of heat from the cores, so will take a chance on that.  The feedlines come straight down over 1/2 wavelength to the ground level, (at least 120' straight down) so that should keep the outer shield currents to a minimum in the first place. No ice can get in now either.

Another good thing is most of the DXing on 75M is done in the cooler/coldest months, so those cores will be starting at 30F or lower.  Or, I'll just have to talk fast and to the point like a corntester...

If these cores get ruined by a lightning strike, I'll climb up there with a hammer and smash them all and replace with clamp-ons to make it easier next time...

FB on your Pug.  They are what we make them - a reflection of us.  Each dog has his own personality and each is different.  Though, I have learned the habits of Springer Spaniels very well.  I can sense when there is a problem while the Vet may think nothing of it.   I've always thought that at 5 years old, a dog becomes the perfect dog. You learn all of their habits and he learns yours. Younger than 5 years old and they can be unruly.  As they get even older, they really mellow out. Their whole life is dedicated to communicating with you. Nothing like an old dog...

Thanks for sticking with me thru this thread and getting most of the problems ironed out.  My usual mode is to do something and then later find out I screwed up a few points and have to redo.  Many times I will hear, "No, no you should have...."   At least this thread has saved me from a lot of those so far...      Frank/ WA1GFZ has been giving me some good tips via email too.
Many of these specific answers cannot be found anywhere.

It looks like T-storms, so more work will have to wait.  At least the feedlines are out there well waterproofed.


Thanks again.

T

BTW, I was thinking about feeding/ phasing... If the two loops were fed in phase, (0 degrees, equal length coaxes) it will produce a bi-directional pattern, but just like the fan dipoles, the bandwidth should really broaden out.  Phased 0,180, the bi-directional pattern will get narrower.  Then fed 0, 90 will give the normal uni-directional beam pattern.  

My point is that the 0,0 feed is like a low angle (average height at 140') broad banded fan to cover the whole 75M band, but bi-directional.  Used in conjunction with the fan dipole gives a local higher angle or lower angle for USA west coast with  similar horizontal patterns.  Each is a very effective antenna in its own right.

[K1JJ]

Here's two articles about a SIMPLE coax phasing method to feed two loops for a directional cardioid pattern.   It requires just two 1/4 wave 75 ohm feedlines and one 50 ohm phasing section. Add one SPST relay to switch directions, or do it manually.

https://www.qsl.net/xe1cdx/Hamdocs/40/40%20Mts%20with%20a%20Phased%20Delta%20Loop.pdf
http://www.iz5ljb.eu/_sgg/phased-inverted-delta.pdf

By good fortune, I already have two 3/4 wave feedlines attached (a multiple of 1/4 wave) and a 50 ohm RG-213 section.

In my case for 75M, it needs two 163' RG-11 feedlines and one 54.5' RG-213 phasing section. Simple.   This is called a force fed system because the power is applied directly to the elements in the proper phase.  A parasitic element uses electromagnetic coupling instead.

This will be the first unidirectional method I try.  I also want to try tuning an element as a reflector using a capacitor -   and also running both elements in phase to check bandwidth and signal strength against the fan dipoles.

To answer my own question from a few days ago, they recommend resonating each loop alone, one at a time, to make them identical.  When brought together, 1/4 wave apart, the swr will not change more than 0.1 according to their tests..

Thanks to Frank GFZ for these article links.

T


EDIT UPDATE:   I'm gonna build this:  Full control of phase and matching with just a few parts.  Just what I've been looking for. (Figure 5)  An L-network to fine tune the loops for optimum f-b (phase) and general performance matching. The only concern is how much loss does it add to the system and feedlines?      Note 10 at the link below bothers me a little...

Called a P/M  -  phase/matching unit

http://techdoc.kvindesland.no/radio/ymse1/20061117162439060.pdf

( I just need another 2000 pF, 3KV vacuum cap...)

[W1ITT]

Tom... I'm looking at the VE3CUI article from the old QST.  I expect that you may not achieve the same SWR bandwidth as he did.  Transmission line theory explains it:  He comes down with his quarter wave transformers of 75 ohm line to his combiner setup.  In your case, because you have a lot more height than he does, you are adding in an extra half wave of line just to get near terra firma. As we know, a half wave of line repeats the impedance from one end to the other.  However, a half wave is different at the CW end from what it is up by the AM phone part of the 40m band.  So the transformer will not be a perfect transformer.  The extra length runs it around the Smith chart faster at the high end than at the low end.
I don't believe the extra half wave will be a deal breaker but it's something to watch out for if SWR bandwidth is important to you. In case you had a very persnickety transmitter, an L-network right in the shack could clean up any sins.  Ordinarily it's best to match nearest the load, but the relatively small mismatch will be easy to compensate, and you won't have to take a long walk in the winter.  Unless Yaz needs to answer the call of nature anyway.
73 de Norm W1ITT

[K9MB]

Those are interesting articles. Frank comes,through again.😎
If it is electrically what is prescribed, it could be great. I wonder if an extra break in tje phasing limes at the shack could allow small sections to be tried for optimal tuning? In other words, make it too short and then be able to put in short sections and test for match and antenna f-b, gain, match, etc? It could save aome cutting and reinstalling connectors during optimization.
It seems, from the articles- a real ionosphere cooker though,when it is going.
73, Mike

[K1JJ]

75M Delta Loops UPDATE 7-27-2022:

Mike and Norm,

FB on all.  

A lot has happened. I haven't decided on the feed system yet. I had some trouble with the loops. They resonated at 4.160 Khz.   Back in 2007 I had shortened them and used a stub to add length. I had forgotten.  Used the formula to bring them down to 3790.

Very productive.  It wasn't easy, but I climbed up there today and added on 24' to one of the loop bases. I changed a few things on the support ropes so that it hangs very nice, like a classic loop should.  The top at 190' and the bottom at 95'.  Avg height above ground now = 142'.  Perfect high angle suppression.

I connected the MFJ at the end of the 173' RG-11 coax.   The swr was  1:1 at 3790 as calculated!  It is reasonably flat from about 3.6 to 3.9.     I  went into the shack and see the same basic swr after the 200' hardline run.

On the air listening, I did a/b tests between the fan dipole and the one loop.  The locals in CT and NY drop down -20 to -30 dB at times on the loop. Low angle loop.  That loop must be at the perfect height to see that.  The few stations that are farther away this afternoon are at least equal on both antennas. I will test on some Eu DX tonight.  The loop is about 6 dB quieter for static noise. It seems to be suppressing the high angle noise.  It is below S1 on the fan, so no worry either way.

Right now the 173' RG-11 drops straight down to the ground, a 95' drop. I will change that later to provide some support on the tower legs.  Norm, I agree that the extra 1/2 wave of coax should not be a deal breaker.

So once I duplicate the second loop, it shud be a good platform to work with. Many things can be tried now. The second element should add 5 dB and make the pattern uni-directional with a good f-b.  The low angle lobe will make a huge difference when the conditions are right. The additional 24' at the base made the loop fill out and  have more area.

The second loop upgrade requires me to hang off the tower on 45 degree rails to access it. Tough game. Not looking forward to that.

A lot has transpired over the last few days with the loops.  It pays not to give up too easily.

Will keep ya updated.

T

[K9MB]

75M Delta Loops UPDATE 7-27-2022:

Mike and Norm,

FB on all.  

A lot has happened. I haven't decided on the feed system yet. I had some trouble with the loops. They resonated at 4.160 Khz.   Back in 2007 I had shortened them and used a stub to add length. I had forgotten.  Used the formula to bring them down to 3790.

Very productive.  It wasn't easy, but I climbed up there today and added on 24' to one of the loop bases. I changed a few things on the support ropes so that it hangs very nice, like a classic loop should.  The top at 190' and the bottom at 95'.  Avg height above ground now = 142'.  Perfect high angle suppression.

I connected the MFJ at the end of the 173' RG-11 coax.   The swr was  1:1 at 3790 as calculated!  It is reasonably flat from about 3.6 to 3.9.     I  went into the shack and see the same basic swr after the 200' hardline run.

On the air listening, I did a/b tests between the fan dipole and the one loop.  The locals in CT and NY drop down -20 to -30 dB at times on the loop. Low angle loop.  That loop must be at the perfect height to see that.  The few stations that are farther away this afternoon are at least equal on both antennas. I will test on some Eu DX tonight.  The loop is about 6 dB quieter for static noise. It seems to be suppressing the high angle noise.  It is below S1 on the fan, so no worry either way.

Right now the 173' RG-11 drops straight down to the ground, a 95' drop. I will change that later to provide some support on the tower legs.  Norm, I agree that the extra 1/2 wave of coax should not be a deal breaker.

So once I duplicate the second loop, it shud be a good platform to work with. Many things can be tried now. The second element should add 5 dB and make the pattern uni-directional with a good f-b.  The low angle lobe will make a huge difference when the conditions are right. The additional 24' at the base made the loop fill out and  have more area.

The second loop upgrade requires me to hang off the tower on 45 degree rails to access it. Tough game. Not looking forward to that.

A lot has transpired over the last few days with the loops.  It pays not to give up too easily.

Will keep ya updated.

T

Tom,
It sounds like you are making great progress. It will be very interesting to get signal reports on comparisons between the Fan and the phased loop array when you get in next Winter night season to Europe on 75 meters.
The low noise floor is very exciting. It will be interesting to compare the loop antenna and a beverage looking at Europe. Obviously, the loop will give stronger signals going and coming, but good S/N with gain is a great thing.
These are very interesting antennas, even as a vicarious experience, so updates are greatly desired. Thank you for sharing your progress. Looking forward to more.
I agree completely that you cannot give up if early phasing schemes give poor results. I agree that adding a half wave of rg11 will add very little loss and the increase in gain will quickly erase a couple of tenths of feedline loss.
You must know that getting one loop going is just an opportunity to start from when you add the second loop. Phasing probably will be critical to optimize the polar plot and radiation angle and match. It is why having the ability to insert short coaxial phasing sections can be good to quickly experiment for optimal phasing.
That 45 degree
Take your time and think three times before you make a move on that 45 degree rails hanging work.
Very exciting work, Tom.

[K1JJ]

Hi Mike,

Yes, the reduction in atmospheric noise does appear to be simple higher angle suppression.  

I have a 600' terminated Beverage aimed NE for Eu that I will compare too. It is about 600' away from the house... very quiet.  Usually in the past, on 75M, the Beverage hears about -3dB poorer than the high loops. Sometimes equal, but that is rare. It is hard to beat a high Yagi of any kind... even a full size beverage falls short... for S/N.  I have a dual diversity system modified into my FT-1000D that uses stereo headphones, one for each channel.  That is some system... (loops and Beverage combined) and gives the brain a binocular effect to work with.  It is still GIGO.  The antennas must work really well individually to work well together.

Last night I tried the loop  A/B thruout the evening against the fan dipoles.  The fan is actually a good DX antenna. (at ~100' avg)    Into EU, the fan was equal to the single loop most of the evening until about 9PM.  Then the loop slowly took over and at 11:20PM  the loop was about 5 dB louder than the fan. The loop's extra height (~142' avg) won over. I figure with the second loop it will be close to 10 dB louder  like in the past.

There is a strong telemetry signal from Eu on 3806 and 3823 I use as a beacon.

I think the 75M angles are higher early in the eve and then drop down late.  It used to be the opposite at the solar minimum IIRC.

From CT, I noticed the W8s and W9s were about 5 dB louder on the loop all night.  I was listening to locals Chuck and Bob/KBW on 3885 at about 7PM..  Chuck almost dropped into the noise on the loop with his high 2-half waves in phase.  Bob dropped -30 dB on the loop but was +50 dB over on the fan dipoles. More evidence we want to see.

And here's a first:  Today at about 11:30AM, daytime absorption conditions, on the the LOOP the LOCALS were consistently 10-15 dB!  LOUDER than on the fan dipoles.  The best path appears to be lower angles in the late morning/afternoon. During high absorption, the low angles are making it thru better.  In contrast, as we have seen, at night the loop is sometimes -30 dB weaker on locals.  

So again, I think all of this evidence points to a good combination of basic antenna potential to arrive at both a great local  and DX system for 75M. To see this much difference with these antennas shows they are well isolated and taking advantage of widely separate angles.  The real testing will be if and when I can get the loops working together. Adding another element (reflector or driven) seems to make an antenna really come to life.

I'll keep you updated as I test more.

T

[K9MB]

Hi Mike,

Yes, the reduction in atmospheric noise does appear to be simple higher angle suppression.  

I have a 600' terminated Beverage aimed NE for Eu that I will compare too. It is about 600' away from the house... very quiet.  Usually in the past, on 75M, the Beverage hears about -3dB poorer than the high loops. Sometimes equal, but that is rare. It is hard to beat a high Yagi of any kind... even a full size beverage falls short... for S/N.  I have a dual diversity system modified into my FT-1000D that uses stereo headphones, one for each channel.  That is some system... (loops and Beverage combined) and gives the brain a binocular effect to work with.  It is still GIGO.  The antennas must work really well individually to work well together.

Last night I tried the loop  A/B thruout the evening against the fan dipoles.  The fan is actually a good DX antenna. (at ~100' avg)    Into EU, the fan was equal to the single loop most of the evening until about 9PM.  Then the loop slowly took over and at 11:20PM  the loop was about 5 dB louder than the fan. The loop's extra height (~142' avg) won over. I figure with the second loop it will be close to 10 dB louder  like in the past.

There is a strong telemetry signal from Eu on 3806 and 3823 I use as a beacon.

I think the 75M angles are higher early in the eve and then drop down late.  It used to be the opposite at the solar minimum IIRC.

From CT, I noticed the W8s and W9s were about 5 dB louder on the loop all night.  I was listening to locals Chuck and Bob/KBW on 3885 at about 7PM..  Chuck almost dropped into the noise on the loop with his high 2-half waves in phase.  Bob dropped -30 dB on the loop but was +50 dB over on the fan dipoles. More evidence we want to see.

And here's a first:  Today at about 11:30AM, daytime absorption conditions, on the the LOOP the LOCALS were consistently 10-15 dB!  LOUDER than on the fan dipoles.  The best path appears to be lower angles in the late morning/afternoon. During high absorption, the low angles are making it thru better.  In contrast, as we have seen, at night the loop is sometimes -30 dB weaker on locals.  

So again, I think all of this evidence points to a good combination of basic antenna potential to arrive at both a great local  and DX system for 75M. To see this much difference with these antennas shows they are well isolated and taking advantage of widely separate angles.  The real testing will be if and when I can get the loops working together. Adding another element (reflector or driven) seems to make an antenna really come to life.

I'll keep you updated as I test more.

T

Very interesting, Tom.
I am a little jealous of your very quiet QTH. I am surprised that your Fan is so quiet, but at near 100 feet, it is up close to a half wave so it is above a lot of near field trash, I suppose. I would have given that 600ft Beverage the edge, but given your excellent local noise floor there, it apparently is not like some of us with lower towers and huge RFI garbage buzzing away from power limes and electronic devices…
That diversity system is a great idea.
The across the pond favoring the fan and then the loop is also interesting. You you suspect multihops early and then fewer hops later as the ionization cools a bit and absorption at lower angles drops or maybe you are skipping over the target area? I need to bone up on propagation. I need to keep reminding myself that Britain and the Norse countries are only 3000 miles over the great circle route from you.
It will be really interesting when you get the second loop phased and drop your take off angle even more. Kind of like the old traditional snow goggles with horizontal slits, that more narrow pattern should eliminate even more noise.
Thanks for the update. 73, Mike

[K1JJ]

UPDATE:  8-1-2022:

Mike and all,

Some good progress on the 75M loops...   The hot and windy weather kept me from climbing for a week or so. The propane torch would not stay lit for soldering. There was hot solder dripping on my leg a few times.

For a few weeks one loop was always the same strength as the reference fan dipoles.  But the last two days I climbed and finished up the basic loop installation.  Now have some feedline dress work to finish up climbing and can then work on the ground for a while.

There's  now two 173' RG-11 coaxial feedlines at ground level with each individual loop resonant on 3790.  I decided to drive one loop and tune the other with a tuning cap to see if there is any forward gain or front to back. (as a parasitic reflector beaning NE, Europe)   I roughly tuned the reflector using a beacon only about 100 yards behind the reflector, looking for a sharp null.  Adding the second loop into the system moved the resonant frequency down from 3790 to 3770. (mutual coupling)

On the FT-1000D I tuned in the 3806 European telemetry station.  FINALLY I was seeing the loops take out the fan dipoles at sunset. They were always dead even before.   I thought it was conditions before, but now I know it was antenna performance.  As the night progressed, the loops were one S unit louder, then two S units and finally on a band peak, (between 11:30 -12 midnight EST)  the loop's peaks were 2 1/2 S units (~15 dB) louder than the fan dipoles! Much depends on conditions.   The loops finally came to life. All that suppressed energy finally showed itself.

Maybe the problem a few weeks ago was either the openwire line causing stray coupling, poor pattern -  and possibly the physical layout of the loops were not very good.  I cut some small trees and weeds so that I can now pull the loops out straight so they align better with each other and the boom.  I will clean it up some more tomorrow to make the layout near textbook perfect..

The local stations before sunset  had huge fades on the loops, sometimes from S9+30 over on the fan dipoles down to S6 on the loops. The high angle suppression is greater than it was before now that the loops are roughly tuned.

Some Puerto Rican stations were barely copy-able off the back, but loud on the fan dipoles.   It's interesting that the fan dipoles are at 100'  and the loops start at 100' and go up to 190'.  They displace different areas and their performance shows it.   Next will try switching the loops NE/SW with the parasitic method. It is working so well I may not bother with the direct driven feeding method and its particular problems.  But I'm always curious and may experiment with the  90 degree phasing section to see how it compares.

BTW, the noise is now even less than before. The loop's background noise, day or night is about 8 dB less than the fan dipoles.  Tuning the reflector to eliminate the noise off the back and suppressing the high angle noise really made a difference.  I can hear better on the loops if only because the noise is less. The signals may be the same strength, but the lower noise makes a huge difference in readability.  I remember that being a nice feature of these loops back in 2010. Glad it is working again.

All in all, I'm very pleased with the loop's overall performance. Was getting a little concerned why I could not beat the fan dipoles. Was thinking the dipoles might be good enough for Eu, but now see that the loops can crush the fan dipoles like a bug, caw mawn.

T

[K9MB]

UPDATE:  8-1-2022:

Mike and all,

Some good progress on the 75M loops...   The hot and windy weather kept me from climbing for a week or so. The propane torch would not stay lit for soldering. I had hot solder dripping on my leg a few times.

For a few weeks one loop was stuck the same strength as the reference fan dipoles.  But the last two days I climbed and finished up the basic loop installation.  I only have some feedline dress work to finish up climbing and can then work on the ground for a while.

I now have two 173' RG-11 coaxial feedlines on the ground with each individual loop resonant on 3790.  I decided to drive one loop and tune the other with a tuning cap to see if there is any forward gain or front to back. (as a parasitic reflector beaning NE, Europe)   I roughly tuned the reflector using a beacon only about 100 yards behind the reflector, looking for a sharp null.  Adding the second loop into the system moved the resonant frequency down from 3790 to 3770. (mutual coupling)

On the FT-1000D I tuned in the 3806 European telemetry station.  FINALLY I was seeing the loops take out the fan dipoles at sunset. They were always dead even before.   I thought it was conditions before, but now I know it was antenna performance.  As the night progressed, the loops were one S unit louder, then two S units and finally on a band peak, the loop's peaks were 2 1/2 S units (~15 dB) louder than the fan dipoles!  

I think the problem a few weeks ago was either the openwire line causing stray coupling, poor pattern -  and possibly the physical layout of the loops were not very good.  I cut some small trees and weeds so that I can now pull the loops out straight so they align better with each other and the boom.  I will clean it up some more tomorrow to make the layout near textbook perfect..

I noticed the local stations before sunset  had huge fades on the loops, sometimes from S9+30 over on the fan dipoles down to S6 on the loops. The high angle suppression is greater than it was before now that the loops are roughly tuned.

I was listening to some Puerto Rican stations that were barely copy-able off the back, but loud on the fan dipoles.   It's interesting that the fan dipoles are at 100'  and the loops start at 100' and go up to 190'.  They displace different areas and their performance shows it.   I will try switching the loops NE/SW with the parasitic method. It is working so well I may not bother with the direct driven feeding method and its particular problems.  But I'm always curious and may experiment with the  90 degree phasing section to see how it compares.

BTW, the noise is now even less than before. The loop's background noise, day or night is about 8 dB less than the fan dipoles.  Tuning the reflector to eliminate the noise off the back and suppressing the high angle noise really made a difference.  I can hear better on the loops if only because the noise is less. The signals may be the same strength, but the lower noise makes a huge difference in readability.  I remember that being a nice feature of these loops back in 2010. Glad it is working again.

All in all, I'm very pleased with the loop's overall performance. I was getting a little concerned why I could not beat the fan dipoles. I was thinking the dipoles might be good enough for Eu, but now see that the loops can crush the fan like a bug, caw mawn.

T

Tom,
Great report on the progress you are making.
All us Monday morning quarterbacks knew all a long that the loops are better! 😉😂😉
Tom, seriously- so many factors can skew results that the fact that the fan seemed better did not mean much, except maybe the second loop was needed, that phasing was off, that some weird ionosperic absorption was causing certain takeoff angles to be attenuated more, to…… whatever.
 The great F-B tells me that you have the phase shift right on and add the huge difference in signal in night conditions and it begins to justify and encourage your massive efforts to put up this huge array.
Antennas make so much difference because it not inly makes you louder, but it increases not only signal strength on receive, but also filters the noise floor by limiting the exposure by only looking at where you need to look for the signal.
My wife and I were talking about seeing something at distance and how you can read a sign further away by looking through a small aperture made with the hand so that only light coming from the object you wish to see while filtering out the glare caused by scattered light that prevents your retina from seeing the image clearly.
We expend so much effort on powerful amps and sophisticated receivers with low noise preamps, but so much more can be achieved if we can make big improvements in antenna performance, or even small measurable improvements.
This is very interesting and inspiring to see you make this sophisticated phased array really improve your ability to both hear and be heard on long hauls in a place in the cycle where most of us are hunkering down for 5 years.
Thanks, as always for the update.
What is the next step? It rally seems to be working very well. 73, Mike

[K1JJ]

Mike,

You made some great points;

"Antennas make so much difference because it not inly makes you louder, but it increases not only signal strength on receive, but also filters the noise floor by limiting the exposure by only looking at where you need to look for the signal."  [MB]

This is so true.  Just like a unidirectional antenna, like a Yagi, can eliminate a whole hemisphere of noise by using a big front to back.  But we need to know what we are optimizing for, horizontal, vertical or both. Stacking antennas can selectively do more of the same  in the vertical plane.

One thing that is very important to antenna testing and evaluation is having a REFERENCE antenna. A simple dipole fed with coax at 1/2 to 1 wavelength high  (or whatever can be erected on the lower bands) is so important. Without the fan dipoles as a reference I never would have known that the single loop was performing normally and that it was performing normally when the reflector was added to the loops. I never would have known that I had a 4 dB intermittent connection on my previous dipole and to replace it.  I never would have known the front to back either.  If I go on to put up a new 20M pair of staked lazy H's, you can be sure the first antenna that goes up will be a 20M dipole at 30 - 65' fed with coax. It's a great way to really evaluate and improve on a complex antenna.

Another technique is to become familiar with the various signals and stations on the band to be able to check for f-b in the real world. When I hear weak, watery signals with a lot of fade off the back, I know I am close to the sweet spot of f-b optimization.  You can also see the band edges where the f-b starts to fade.

On 40M my reference antennas are a dipole at 45' and a dipole at 100' high.  They are vastly different antennas. They told me I had problems with the 40M triple stack and fixed it. The broken stack was the same strength as the references into Eu. But now the stack is louder by at least 2  units on good nights.  Coax contamination is another problem that can creep up and a reference antenna can show this over time, if you keep notes. Of course band conditions change over the solar cycle, so it can be tricky.


There's noting like a well performing array, but it takes a lot of time and work to get there.  I get a lot of enjoyment just switching bands and trying the antennas against their references to see how conditions are and to insure the antennas are still working right.

Something I noticed yesterday.... time seems to speed up when tower climbing. Yesterday I went out and started the climb at  10:30AM and finished, and came down.  I went inside thinking I had been out for about an hour. I was amazed to see it was almost 2PM and I had been climbing for 3 1/2 hours. I was sore, but never saw the time go by so fast. Like working in a black hole as the outside world speeds up.

I'll keep you updated as I build and test a switching system for NE/ Eu and SW / USA for the loops.  I'll also post a few pics of the loop's improved physical layout alignment and independent feedline support when completed.

T


**Just for reference, here is a pic of the 75M loops at 190' high last month using openwire. The physical alignment is decent but not perfect.  The 40M reference dipole at 100' is directly under it.

[K9MB]

Mike,

You made some great points;

"Antennas make so much difference because it not inly makes you louder, but it increases not only signal strength on receive, but also filters the noise floor by limiting the exposure by only looking at where you need to look for the signal."  [MB]

This is so true.  Just like a unidirectional antenna, like a Yagi, can eliminate a whole hemisphere of noise by using a big front to back.  But we need to know what we are optimizing for, horizontal, vertical or both. Stacking antennas can selectively do more of the same  in the vertical plane.

One thing that is very important to antenna testing and evaluation is having a REFERENCE antenna. A simple dipole fed with coax at 1/2 to 1 wavelength high  (or whatever can be erected on the lower bands) is so important. Without the fan dipoles as a reference I never would have known that the single loop was performing normally and that it was performing normally when the reflector was added to the loops. I never would have known that I had a 4 dB intermittent connection on my previous dipole and to replace it.  I never would have known the front to back either.  If I go on to put up a new 20M pair of staked lazy H's, you can be sure the first antenna that goes up will be a 20M dipole at 30 - 65' fed with coax. It's a great way to really evaluate and improve on a complex antenna.

Another technique is to become familiar with the various signals and stations on the band to be able to check for f-b in the real world. When I hear weak, watery signals with a lot of fade off the back, I know I am close to the sweet spot of f-b optimization.  You can also see the band edges where the f-b starts to fade.

On 40M my reference antennas are a dipole at 45' and a dipole at 100' high.  They are vastly different antennas. They told me I had problems with the 40M triple stack and fixed it. The broken stack was the same strength as the references into Eu. But now the stack is louder by at least 2  units on good nights.  Coax contamination is another problem that can creep up and a reference antenna can show this over time, if you keep notes. Of course band conditions change over the solar cycle, so it can be tricky.


There's noting like a well performing array, but it takes a lot of time and work to get there.  I get a lot of enjoyment just switching bands and trying the antennas against their references to see how conditions are and to insure the antennas are still working right.

Something I noticed yesterday.... time seems to speed up when tower climbing. Yesterday I went out and started the climb at  10:30AM and finished, and came down.  I went inside thinking I had been out for about an hour. I was amazed to see it was almost 2PM and I had been climbing for 3 1/2 hours. I was sore, but never saw the time go by so fast. Like working in a black hole as the outside world speeds up.

I'll keep you updated as I build and test a switching system for NE/ Eu and SW / USA for the loops.  I'll also post a few pics of the loop's improved physical layout alignment and independent feedline support when completed.

T


**Just for reference, here is a pic of the 75M loops at 190' high last month using openwire. The physical alignment is decent but not perfect.  The 40M reference dipole at 100' is directly under it.

Tom,
I have developed products for 46 years and I can tell you that you understand the process very well.
Standards and changing one independent variable at a time are crucial if you want real progress. Shortcuts seem easy, but there are a ton of unproductive bypaths snd pits there.
You are building a knowledge that will be very valuable to others. You know that you are not done and that is also crucial.
This is very exciting work.

By the way, the disappearance of the sense of time is called “Flow state”.
Google it. Every significant inventor and master of almost any art or discipline lives in it.
I have experienced it since I was a teenager.
Many think it weird when you talk about it though…. The cool people love ADHD better with lots of Twitter posts …😉😂😂😂

[K1JJ]

Hi Mike -

Ahhh, the flow state. I have read a few books on it and studied it closely in regards to day trading.  Really good traders do indeed enter this state and become one with the market or whatever skill they need. Intuition plays a big role too. Just like a doctor who has years of experience, he can just feel the solution.

Other than high speed CW, I've never thought of the flow state related to ham radio, however. It must be the same thing, why not? In my case I was focusing intently on the tower work to make the fear go away. I pretend I am in the shack working on a project and the fear of heights gets under control. It works for me because after a few hours the project is completed and I'm climbing down -  and   not fearful anymore. It's the anticipation that's the killer...it's sometimes harder to saddle up the horse and put on the harness than anything else.

I did some ground clearing today and positioned the loops close to perfect alignment with each other and the boom direction. The coax feed point swings on a 40' rope off the tower to distribute the weigh better.  I tuned in the 3806 Euro beacon tonight and see conditions are pretty hot. The loops are working better than even last night.  I may switch directions to the SW with clip leads and see how it does. Since everything has been matched, it should work just as well to the SW using the same parameters.

T

Notice the symmetrical flow of the repositioned loops.  (#10 THHS stranded copper)

Pic #1 and #2 show the new RG-11 coax and feedpoints at the 100' level. They will be supported on the tower legs from 70' and down.  The small 'T's   are the feedpoint PVC center insulator and the string of ferrite beads. The coax is supported by a Chinese fingergrip pipe hitch knot to better distribute stress across the coax.  I've seen the the finger grip used by commercial installers.

Mixed into the picture frames are wires from the fan dipoles and the two 40M dipoles.  The fan dipoles are end to end with the loops, no overlapping. This should maintain good isolation on 75M. They act well isolated on receive often with opposite signal strength.

[K1JJ]

Pic #3, cleared by hand to give loop anchoring guys the correct position.  The boom length gives about 45' spacing IIRC.     Also repositioned the two 40M dipoles to make the legs perpendicular/ square.

Pic #2 is looking thru guy wires from the Rohn 45 150'er.