Antenna Advice

[ka4koe]

Last batch

[K1JJ]

Hi Terry,

On 160M, the difference between 200' at the same height and hanging the ends down will not affect the pattern much.  But it will have an effect on the higher bands.    If you use the antenna for 40-10M a lot, then I would keep the whole thing at 60', 200' long.  If it is just a 160-80M antenna, then drop the ends so that 160M is most efficient.  The 80M band will have some slight bi-directional gain.


Dennis, that sounds like a vely efficient antenna, being made entirely of #6 wire.  I once had a 123' dipole fed with open wire just like that. My friend calculated the loss difference to be insignificant compared to using #12 wire.  But if the antenna were a shortened dipole, like 60' long used on 80M, it would make a big difference.  The higher bands will have many high current spots, so it will help there.

Anyway, 400' is quite big.  On 80M, 310' long is about the longest we can go before the bi-directional figure 8 starts to get significant side lobes. So on 80M, you probably have four lobes.  (two main and two smaller) On 160M, you would see a dB or so of bi-directional gain, IF the antenna was high enough.  On the bands 40M - 10M it would break into more lobes and nulls... and have more directivity off the ends.

T

[W7TFO]

Thanks, Tom.

I am planning now, and have a lot of room for this.  I'll take your advice and shorten up the plan a bit.

I was going to put up just one antenna at present, and wanted it to be the best I could get with simplicity of construction.

73DG

[K1JJ]

Thanks, Tom.

I am planning now, and have a lot of room for this.  I'll take your advice and shorten up the plan a bit.

I was going to put up just one antenna at present, and wanted it to be the best I could get with simplicity of construction.

73DG

Dennis,

Yep, it's not how much wire is in the air, but how it is phased.  We can have a 5000' long dipole, but if the lobes are many and facing in the wrong directions, it will have negative gain compared to a simple 1/2 wave dipole in the right direction.   The idea of lots of wire in the air applies to getting needed efficiency on the LW frequencies, etc.   Once we have 1/2 wavelength of wire, on the higher ham bands, it's all about phasing.

If one had the room, I still think a pair of phased, coaxially fed dipoles at 50'- 90' high is the best antenna for the bux on 80 and 40M.   Switch it NE, SW or cloud-burner modes.


Phil's 180' antenna plots above are revealing. It looks good on 160, 80M and 40M.    180', no longer,  JUST works for 40M.   But on 20M - 10M  there's more radiation off the ends of the dipole. That is OK if that's what we want, but remember that on 80M we are radiating broadside.  We will be loud in Calif on 80M and 40M -  and loud in Florida on 20M - 10M.... :-)     That's the advantage of separate dipoles that can be faced figure-8 broadside in the desired direction.  

Actually that skirted dipole is not as lumpy on the higher bands as I  thought. Maybe the skirted ends help. It's a fine multiband antenna, really, compared to the commercial gimmick antennas out there.. We just need a good, heavy duty link coupled balanced tuner to finish the job.

T

[W2VW]

Coax is for sissies.

[K1JJ]

Thanks, Tom.

I am planning now, and have a lot of room for this.  I'll take your advice and shorten up the plan a bit.

I was going to put up just one antenna at present, and wanted it to be the best I could get with simplicity of construction.

73DG

Dennis,

Another thing, since you haven't put up your antenna yet....

The longer the antenna, the higher above ground it needs to be to achieve the same vertical take-off angle.    For example, a center-fed 240' dipole on 80M may have to be at 80' to show the same vertical takeoff as a 123' dipole at 60'.  Probably has to do with higher ground losses due to higher coupling of a longer antenna to Earth ground.

So, it might even be better if you make your dipole 240' at 60' high to cover 160M and call it done.  A reasonable vertical take off angle is very hard to get on 160M, so we need all the help we can get.

T 

[ka4koe]

BTW, those plots are combined H+V.

P

[Steve - K4HX]

Or should I just leave the wire at 200' in length and keep the ends 60' high - as far from the ground as possible?

I'd opt for the flat-top as high as possible for best 160 meter performance, unless you want to use coax. The ends hanging down may help avoid some pattern break up on the higher bands, but there's no guarantee. I guess it depends on how much you plan to operate on the higher frequency bands, and/or if you can/will put up a separate system for 20-10 meters.

My 160 meter horizontal antenns over the yeas have never been more than 70 feet high (some in the 50 foot range). I have still been able to make 100s of AM contacts (5-10 contacts nearly daily back in the 90s), never running more than 300 watts. On slop bucket I have something like 40 countries worked with a 70 foot high dipole.

Get on 160 and see what happens. If you want to try a vertical or Inverted-L later, you can.

[W7TFO]

My situation is we have two granite hills on the acreage, and I was going to suspend it between them. 

Can't do to much to work a different alignment, so a pretty much N-S stretch is it.

No matter how it will play is better than not being on at all.

Besides, there are a lot of Watts waiting in the wings for their time in the limelight.  Now if I just had something important to say then....

73DG

[ka4koe]

By a bizarre alignment of the planets or other mechanism, I already possess most of the parts to make a balanced tuna; HV 500 PF bread slicer and an EF Johnson 28 uH roller inductor. All I need to do is find another EF Johnson #229-203 roller inductor and we're cooking with gas.

Philip

[W2VW]

By a bizarre alignment of the planets or other mechanism, I already possess most of the parts to make a balanced tuna; HV 500 PF bread slicer and an EF Johnson 28 uH roller inductor. All I need to do is find another EF Johnson #229-203 roller inductor and we're cooking with gas.

Philip

Fleep,

    It isn't necessary to use expensive ganged roller inductors. That's nice to have but a pair of identical coils works also. I've wound my own in pairs several times.

The balanced design can be a a lot of work to find settings the first time but well worth the effort.

Better than link tuners for band cruising because they are not bandpass filters.

Can be configured to keep all wire in the air at D.C. ground. Some people like this for static dissipation. Yeah that can be done with a pair of resistors on a linky setup.

Not likely to wind up with a power robbing awful Q situation as you can with high pass T networks along with some poorly thought out link setups.

Can be built with extreme impedance matching range and work well. 

[ka4koe]

With my history with Thor, I'm already performing some thought experiments on how to ground this antenna prior to entry into the house. Reference paragraph 1:

http://www.iceradioproducts.com/30.htm

So I will need to bring the ladder line close to ground, anchor near a ground rod, install lightning arresting/ground means, then route back up to eave, through attic, and terminate at my second floor shack. I also do NOT intend to install the vertical run up to eave directly adjacent to the downward lead to avoid flashovers.

The final version will enable me to completely disconnect/isolate the portion of the feedline that enters the house while shorting/grounding the lead from the antenna.

The center will be supported by a tree at about 60'. The ladder line will drape away from the tree at about a 15 degree angle to the vertical.

Any pitfalls to my approach??

[W2NBC]

Matching rollers aren't always expensive:


http://www.ebay.com/itm/E-F-JOHNSON-229-203-ROTARY-INDUCTOR-/251582035396?pt=US_Ham_Radio_Transmitters&hash=item3a937535c4

[ka4koe]

Got it. Thanks for the link.
 

[W2VW]

That's a good deal and a lot less than they were Jeff. A couple more deals like that and you and I can afford a classic Mercedes.

[ka4koe]

Best price I've found on a 500' roll of #14 AWG THHN/THWN is 40 bux @ Lowes/Home Despot. A local electrical supply house had it for almost exactly the same price.

Only problem I've noted in the past is the outer coating flakes off quickly due to UV and uglifies the whole shebang.

[Pete, WA2CWA]

Best price I've found on a 500' roll of #14 AWG THHN/THWN is 40 bux @ Lowes/Home Despot. A local electrical supply house had it for almost exactly the same price.

Only problem I've noted in the past is the outer coating flakes off quickly due to UV and uglifies the whole shebang.

I've used Home Depot wire for antennas, and after roughly 15 years, it still looks fine.

But, if UV is your pressing issue, go here:
http://www.dxengineering.com/parts/dxe-antw-500

[ka4koe]

Must have been the brand I was using. Anyway, found a copy of Ed Bigbie's article (I knew Ed personally and he lived not that far from me) quoted from friend Mark's blog:

http://ka4cid.blogspot.com/2008/12/w4mmq-legacy-balanced-antenna-tuner.html

[Ralph W3GL]

That's a good deal and a lot less than they were Jeff. A couple more deals like that and you and I can afford a classic Mercedes.

What happened to the pair you had?

[W2VW]

THHN can get ugly. Lighter colors seem to take longer shedding the clear coating.

What happened to the pair you had?

I've had 3 sets in use over the years. One was sold on epay to a ham in Studio City Ca. Sold the second set to members here.

The pair on the K3L 2005 / W2A coupler is not really a pair. The pitch and turns count are different. No effort was made to gang any.

Still using the different ones as a band cruiser. Find the necessary values and build a permanent setup after.

 

[Ralph W3GL]

That's a good deal and a lot less than they were Jeff. A couple more deals like that and you and I can afford a classic Mercedes.

What happened to the pair you had?

Nah, I was refering to the "classic Mercedes" part of the post, Dave...

[W2VW]

That's a good deal and a lot less than they were Jeff. A couple more deals like that and you and I can afford a classic Mercedes.

What happened to the pair you had?

Nah, I was refering to the "classic Mercedes" part of the post, Dave...

Thread needs an NPO. I still have both W-140s.

[W7TFO]

Somewheres out on the land is our '59 219 .

Gotta go look for it.

73DG

[K6IC]

Regarding THHN Building Wire for antennas;

Black insulation holds up quite well.  In a year or three,  the clear Mylar(tm)/polyester coating on the wire delaminates,  and falls off,  but the black PVC insulation seems to hold up.   Some of the black insulated THHN antennas,  here,   have been up for a couple of decades,  and seem to be going strong.

Had tried lighter colors,  and green insulation.  On these antennas,  the PVC  started rotting in a few years.

YMMV.     Have Fun,     Vic

[ka4koe]

May wait to the fall to do all this work. Frankly, this bod doesn't do well in high heat/humidity anymore. One has to do lawn work by getting up prior to the crack o' dawn.