160M Antenna

[AB3FL]

I have a question for all of you on "top band"

What kind of antenner are you using?  I do not have room for a beverage or full size 160M dipole.  My 80M dipole is diagonally across my yard and only has a little room to space. 


thanks

Tom - AB3FL

[K5UJ]

inverted L.  it's the only semi-effective (or effective depending on the ground system and height) antenna for 160 that can be squeezed into a small space.  Tune it at the f/p if you want, or in the shack.  Use decent coax; not 58U or 8X -- some hams will tell you they're okay because of the low frequency; they're not.  You have to work against ground for transmitting unless you can get something horizontal over 100 feet high.    Also forget Voyager, isotron, any of those something for nothing antennas.  The horiz. part of the L doesn't have to be straight.  You can bend it around as long as you don't bend it back on itself, i.e. no angles < 90 degrees.

Rob

[K5UJ]

oh yeah, it helps a lot if the vertical part is at least 50 feet.  Lots of relatively short radials < = 50 feet okay.   

[Ed/KB1HYS]

Any low radiator is going to be a cloud burner. It's pretty hard to get more than a quarter wave high on 160.

I have a small city lot 100x100, I put up a full sized 160meter dipole by zigging it around in the shape of a crazy-Z using pulleys and other ropes through trees in the yard,  with the ends drooping to about 15 ft or so above the ground. I feed it with the heavy duty TV twin lead and feed it through a HB balanced tuner for all band use. (NO QRO here   ) 

I've tried modeling it, and at it's average height (~40ft) it's a wash. Just one big 'Ball' of a pattern.

  It work OK fine for me, in my situation, as I can work most folks out a few hundred miles or so, and I can get multi-band use from one antenna. I'm not a DX hound on 160 so the lack of low angles doesn't bother me, and the system is fairly compliant with the XYL's requirements too (ya gotta LIVE with 'em right?)

get up as much wire as you can, as high as you can. Use a decent ground system and tuner. Accept the fact that you will not match performance with guys who own 60 acre antenna farms with stacked Rhombics and towers and spend the time you would have wasted seeking that last dB of performance from a mediocre system on on the air.

[Jim, W5JO]

If you want local only then put up the dipole as high as you can.  If you want to talk to the middle of the US, and sometimes to the other coast, then put up something vertical like the inverted L Rob mentioned.  That will give you a much better chance to distance.  Put down as many radials as possible to form a good screen at the base.

I regularly listen to 160 and those on the East Coast who use the dipole cannot be detected but those who have vertical polarization are much better in the South of Oklahoma.  I would talk but not many AM operators here will get on 160 and I hestitate to break into QSOs that I cannot hear everyone.

Make the L ~ 160-170 ft. fed with a series cap (prefferably a variable) of about 250 pf.  Then you can easily use 50 ohm coax.  I mounted my cap in a poly Post Office box.  With this kind of installation and a good (I mean a good) tuner, you can load the antenna on all bands.

[ka3zlr]

Could give this one a try.

http://www.amwindow.org/tech/htm/160smallants.htm

73
Jack.

[VE3GZB]

When I was testing my antenna recently on 80m using 100W, it was picked up in Vermont by KF1Z at S9, that's 600km straight-line east of me. It was also picked up in Ottawa by VE3WXB and by VE3AWA in St. Marys at S8, that's 150km southwest of me and by VE3VJ who is about 150km south of me who rated the signal 429.

http://amfone.net/Amforum/index.php?topic=21205.msg150238#msg150238

I have a very small lot in the village and I've had no luck in trying inverted L, dipole, Zepp, loaded dipoles - all garbage because for any height to work with, I have only 50 linear feet to play with.

I work with loop antennas daily at my job in RFID.

Here's a brief thing about them (but the tag shown is in the hardest to detect position - best detection occurs when the plane of the tag's coils are parallel with the plane of the loop windings):

http://electronics.howstuffworks.com/gadgets/high-tech-gadgets/anti-shoplifting-device3.htm

So I just I wound a vertical loop using a pair of 16ga outdoor speaker wire connected in parallel on the deck railing, used insulated nails to anchor it to the wood, made a hole in the wall through the aluminum siding, put in a bit of PVC pipe to act as wire conduit, terminated the loop inside the house directly to the cap-side of an L tuner on my homebrew transmitter.

The loop I'm using is "L" shaped because I wound it to encompass part of the E-W railing as well as the N-S railing. So total loop size encompassing the E-W and N-S rails would be 4 ft X 16 ft and it measures about 33uH.

If you don't believe in loop antennas, just look in any store where the antishoplifting antennas are set up. Unless they are acoustic systems, most of them are HF (from 1.5 to 13.6 Mhz depending on the system) vertical loop antennas inside. The RF radiates perpendicular to the loop wire, that's why those systems work vertically.

Try the same thing at your home. See if you get any results.

PS: One of our new products is a hybrid system which transmits 8.2MHz with a conventional Faraday-shielded single-turn loop (6uH) as well as transmitting 5kHz with a pair of 10"X10" tuned loops (each loop is in series yielding a total of 120uH, yup, at 5kHz!).

Faraday-shielded loops work well by the thousands in stores all over the world as long as you resonate them and get the circulating current going well and don't short out the Faraday shield - that's the key!

[k4kyv]

My first 160m antenna was an inverted-V, 40 ft. high at the apex, drooping down to about 15 ft. each end.

Something hilarious, the poles that I used  to support the ends were made from young trees I cut from the woods.  The following spring after I erected the antenna the autumn before, those poles began to grow branches and sprout leaves!  I kept it up another year or two, and by the time I took it down, the wood had completely rotted off at ground level.  The only thing holding up the poles was the two  guy wires and the antenna.

But with that antenna I had good results within a radius of 450 miles or so, running the legal limit of the day, 50 watts at night and 200 watts day.  We were limited to 1800-1825 kHz,  while those in the western part of the country were limited to 1975-2000.  To work coast-to-coast you had to work cross-band.

At one time the FCC proposed to prohibit SSB, but the Navy and Coast Guard ran some tests and determined that SSB would not cause undue interference to LORAN, so the SSB prohibition was lifted before it was to go into effect (damn!).

Eventually, more of the band began to be re-opened to hams as the LORAN-A system was slowly but surely being phased out.  Thanks to a few of us hardy souls who continued to operate the band during a period when the appliance ads in QST touted "All-band, 80-10m" transmitters and receivers, we were able to hold onto it until the FCC began to relax the restrictions imposed while we shared it with LORAN.

But we have yet to get the entire band back.  For many years prior to WW2, the band ran from 1715 to 2000 kHz.  There were sub-bands at the time; 1715-1800 was CW only, and 1800-2000 was CW and phone.  Just before Pearl Harbor, the band was shifted to 1750-2050.  We had a  full 300 kHz!  But I am not sure those privileges ever went into effect before the WW2 shut-down.  I have an old National NC-101XA receiver with the tuning dial calibrated for 1.75-2.05, with about 35 kHz of additional margin at each end.

[KM1H]

Polarization and angles is black magic on 160. I cracked a monster pileup on an Antartic area island Dxpedition when I first moved here with an Inverted Vee with the apex at 50' and the ends at 4'.
I also worked Australia with it as well as a fair amount of Europeans.

Other times I couldnt buy a QSO.

These days I have a high inverted vee and verticals and can monitor the shift from high to low angles.

Carl
KM1H

[ke7trp]

I use an inverted L.   I already had a Tower up with a Pulley so it was easy for me to install.  I ran RG213 to the base of the tower. Grounded the shield side to the tower leg, Ran the Center up the tower and then put an insulated pipe between the tower and the wire (to keep the wire from touching the tower). This pipe is about 3 feet long.  The wire bends over about 50ft up. Then the wire runs out to rope and then to the Wooden Fence.  All of this took me about an hour to install. I pruned the wire until I was flat on 1885.  I use a Palstar tuner with this antenna.  It works better then I ever imagined. I only have Three Raised Ground wires from the tower base out and these are only about 60Ft long.

very cheap, Very simple. Works very well. I dont have the space for a half wave dipole.

Clark

[flintstone mop]

.  I use a Palstar tuner with this antenna.  It works better then I ever imagined. I only have Three Raised Ground wires from the tower base out and these are only about 60Ft long.

.

Clark

The best kept secret is the raised radials...........................

Fred

[ke7trp]

I agree!!  Now if I can keep Toby the dog from tearing them down, I am all set!


Clark

[Opcom]

What's going up is a 100FT dipole, 50FT at the center. The old buzzards tell me to use it on 160M by shorting the ladder lines together at the station entry and feeding "that" against the nearby ground rod, a good ground. I was told "you better get a helluva tuner built up for that too cause it aint gonnal like it no matter that you do". Not sure that helps.

[KX5JT]

.  I use a Palstar tuner with this antenna.  It works better then I ever imagined. I only have Three Raised Ground wires from the tower base out and these are only about 60Ft long.

.

Clark

The best kept secret is the raised radials...........................

Fred

With regards to the raised radials.... how high up?  (the dog tearing them down leads me to think they aren't raised too high!)  Also... are they going out in all different directions are are they mostly running out underneath the direction of the top of the L ?  

Does the antenna favor directions like where the top of the L points or maybe broadside to the horizontal top?  Just curious.... one day I'm going to have to figure out something for 160.

[ke7trp]

The tower is near the corner of the house.. So one runs down the house,  The other two, are running out into the yard. Just like 4 point star with one point missing.  The feed point is 1 to 2 feet above soil at the tower leg, The ends of the ground wires are to the 6ft fence line.  The dog runs around the side yard at full clip and tags the lines.  I have him trained to leave all but one alone.. LOL.

I notice no directionality.  Its a sky burner for sure.. But it shure does work well.  I can compete with people running all types of 160 antennas in my area. Its very possible, This is loading the 60 foot tower though!


Clark

[K5UJ]

I've always been told that elevated radials are great but they have to be elevated a fraction of a wavelength at the operating frequency to function the way they are supposed to, at least .1 wavelength up I think.  On 160 that is beyond what most hams can do although some pull it off because they have big tall towers (W0AIH comes to mind).  If they are lower than that they are so close to ground that for all practical purposes, they may as well be lying on the ground. 

tying the ends of parallel wire feed to a dipole and feeding that so it is a T vertical is a great idea too, provided the total length of the T is enough and since it is fed against ground, there are radials down extending out from were the T is fed.

73
Rob K5UJ

[KM1H]

Elevated radials work best above a poor ground as the coupling is minimized. On my rock pile Ive no idea at what depth where a DC or RF ground actually exists.

Ive had exceptional performance with 32 radials at 10-12' up on a 160M phased pair sloping off the tower top guys. Exceptional means consistent pileup busting as well as among the highest band results in contests. Also won a 160M contest or two. All done at 1200W which is many dB below the competition DXers and contesters.

Carl
KM1H

[k4kyv]

With a system of buried radials or radials lying on the surface, the direction the radials are laid out has minimal effect on directivity of the antenna.  Leaving a large segment of the circle surrounding the antenna devoid of radials increases ground losses, regardless of the number of radials laid out in other directions.  Once you reach the point of diminishing returns, additional radials in the part of the circle where the ground  plane lies will have little effect because in that sector the earth is already effectively shielded from the antenna, while that open sector without radials still generates losses in all directions.

Once you exit the near-field of the antenna, the segment of the circle without radials has little or no effect on the radiation pattern.  It simply decreases field strength in all directions.

With elevated radials (a.k.a. counterpoise), the direction they are laid out may have more effect on the pattern.

[KD6VXI]

With elevated radials (a.k.a. counterpoise), the direction they are laid out may have more effect on the pattern.

I can attest to this being true as follows:

Back in the 11 meter days of the 80s, I worked on a station that had a 70 foot tower, almost 2 wavelengths high, when you factor in about 25 feet of pole extending atop the tower, give or take (can't remember now) for a horizontal 8 element beam and 18 feet above it was a "starduster" antenna, basically a drooping radial quarter wave vertical.

This station was about 2000 feet above sea level in San Diego, and when the BEAM was pointed at either the Pacific region or Easterly for US DX, we couldn't hear or qso with Los Angeles... While we where on the VERTICAL.  The beam and the vertical where fed seperately into a switchbox mounted on the wall.  From there it went into the PA.

As soon as we would swing the antenna towards Los Angeles, they would pop up about 10-15 dB... And we could QSO with them.

So yeah, get it up a wavelength or more (in this case, 2), and elevated radials can make a HUGE difference in the pattern of the antenna.

--Shane

[KD6VXI]

For someone who has very limited space you can just construct a simple and even short vertical by coiling the correct length of wire around some PVC pipe or something similar, even wood in a telescopic configuration. Thicker at the bottom and skinner at the top. Then mount and connect a round metal disc (top hat) at the very top of the vertical. Hammer an 8’ ground rod into the ground and lay/bury as many ground radials as you can even if they are not a full ¼ wave length. Just do what you can. Just make sure the vertical starts right at ground level, just a few inches above.

This same antenna was just described in one of the latest QST's, a shortened 160 helically loaded vertical.

I used a trash can lid before as a cap hat.  Worked OK, but rusted eventually

--Shane

[K5UJ]

The vintage radio column in QST is interesting but that alone may not make the whole thing worthwhile.

I did not think of the poor ground conductivity situation when I posted what I did about height of elevated radials on 160 so thanks Carl for mentioning that.

Rob

[KD6VXI]

Back in the 11 meter days of the 80s

There is a big difference between radial techniques used with 11 meter antennas as compared 160 meter antennas.

I agree 100 percent.

Should you re-read what I wrote, I was referencing elevated ground radials and their effect when placed > 1 wavelength above ground, as they  where in that spot.

Having elevated ground radials is having elevated ground radials.  As long as it's all scaled the same way, 11 meters / 160 meters / 70 cm, it will all work the same, SCALED ACCORDINGLY.

That's all I was saying.  It wasn't to prove anything other than if you raise your radials above ground by an appreciable amount in reference to wavelength, the pattern of said ground radials CAN play with the pattern of the antenna.

If you have the radials at ground level, it means little to nothing... As was also evidenced when we'd crank the tower down.


--Shane

[KD6VXI]

This same antenna was just described in one of the latest QST's, a shortened 160 helically loaded vertical.

Really? I get QST, but I never even look inside the magazine.

June 2009, page 32, for those that might have it digitally.

As an aside, it was written by someone almost locally to me, about 30-50 miles away, depending on which thermal the crow runs on  

--Shane