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Author Topic: 80 & 160 meter antenna  (Read 5020 times)
N7GCO
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Posts: 142




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« on: August 17, 2011, 08:42:37 PM »

I am  very interested in getting a better antenna on 80 meters and finally getting on to 160 meters.  I have a small lot, and only have a maximum 100' for a dipole or wire antenna. Does anyone know a good plan or good antenna that will work on both 80 and 160 that will fit in 100' or less? Must be able to to handle high power.

I would also be open to a vertical, but I almost no room for radials.
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AE5JU
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Posts: 223




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« Reply #1 on: August 17, 2011, 09:21:37 PM »

I have plans for both that will fit your available space.  Email me my call at arrl dot net.

Warning, on 160 m there are just 8 or 10 old f--ts who talk about the same thing every night.  Huntin', fishin', coon dogs, amplifiers and hernias.  Every night.  I think it is recorded and they take turns playing the tape.  But they do ID every 10 minutes like clockwork.   Cheesy

I was kidding.  Actually, though I can't transmit on 160 m, I've learned a lot about antennas and amps just listening.  There is some BS on there, like, "Well, ole Jim-Bob put up his tower and only put two guy wires on it 'cause the prevailin' wind was always from the east.  Figgered that was all he needed.  Well, one day a storm come up and the wind changed directions and..."

73,
Paul - AE5JU



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W3HKK
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Posts: 593




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« Reply #2 on: August 18, 2011, 05:16:27 AM »

Dont be afraid to drop the ends of your antennas or bend them.  ie the 80m dipole as high as possible and then drop the ends  to get to resonance.

Inverted Ls are another great way to get on 160 or 80.  Put up the vertical part as high as possible adn then run the remainder out, and drop it down as necessary or bend it.  Put in a ground rod and couple of radials as long as possible and you will work ok. 

Ive worked a fair bit of DX with a 15 ft high 160m inv L.  The far end is 6 ft off the ground.  I use a ground rod and 2  qtr wave radials.

More short radials is better than a few  qtr wave ones.
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K9IUQ
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Posts: 1626




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« Reply #3 on: August 18, 2011, 08:24:54 AM »

Warning, on 160 m there are just 8 or 10 old f--ts who talk about the same thing every night.  

Not True. DX is alive and well on 160 mtrs. Tune 1820-1840, you have to be able to copy CW.  Cheesy There is also a fair amount of digital operation in the lower part of the band.

You also have to have something other than a 160 mtr dipole at 40 ft. Think vertical or inverted L.

In the Winter months I can work EU every night on 160 mtrs and I live the Black Hole midwest.
South Pacific in early mornings too.

Stan K9IUQ
« Last Edit: August 18, 2011, 08:27:36 AM by K9IUQ » Logged
W8JI
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« Reply #4 on: August 18, 2011, 08:57:52 AM »

People rag chew on 160? I thought it was a DX band.

Think vertical. Think inverted L or T antenna for 160.
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K8GU
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« Reply #5 on: August 18, 2011, 09:03:49 AM »

I live on a standard 50'x100' city lot and I have a top-loaded (mostly---also has a small coil at the base) T vertical on 160 and a full-size wire 1/4-wave on 80 that share a (poor) radial field.  They work pretty well for my purposes (casual barefoot DXing and contesting mostly).  The important thing with an installation like this is to get enough wire in the ground and install separate low-noise RX antennas as needed and possible.
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K0ZN
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Posts: 1533




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« Reply #6 on: August 18, 2011, 06:06:12 PM »

Respectfully, the first thing you need to do is put in some study time in the ARRL Antenna Book on antennas for 80 and 160.  You  CAN  do pretty well from
a city lot, but the key to doing that is knowledge of antenna design. This is NOT complex or complicated, but not something you can guess at. Reduced space antennas
for the low bands usually require some simple matching networks to efficiently transfer power to them so you need and idea of what you need to do in this area too. 

I had a surprisingly efficient Inverted L antenna on 160 from a small city lot. It was bent and "top loaded" and did far better than it should have! The main problem with any horizontal antenna on 160 and also on 80 for most people is that the antenna is electrically VERY low. That causes losses, high radiation angles, etc. An Inverted L as W8JI suggested may have some losses if your ground system is marginal, but at least the radiation angle is much lower and probably better over all. You CAN zig and zag or bend around the top "horizontal" portion of an Inverted L with minimal problems on 160. On 80 M, if you "just GOTTA have coax feed", you can easily build and tune
a shortened dipole with loading coils. You can also zig, zag or "U" this antenna. The center of the dipole does most of the radiating, so shortening the antenna with loading coils can have less effect than you might expect. Again, all of this is covered in detail in the ARRL Antenna Book.

What a lot of people don't stop to think about is radiated power. Say, for example, if your antenna has a 50% loss (a VERY realistic number for a small antenna and poor ground system on 160...), if you put 1,000 watts into the antenna, you still have a 500 watt signal and 500 watts is a pretty decent power level and you can and will make a lot of contacts at this power level. Will you be "The Band Master" ?? NO !....but you can easily work all over the country on this system, especially if you work CW.

Good luck on your project.

73,  K0ZN
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AE5JU
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« Reply #7 on: August 18, 2011, 09:16:50 PM »

Seems I saw a 160 m vertical in QST in the past 2 years.  Don't remember the issue.
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AE5JU
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Posts: 223




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« Reply #8 on: August 18, 2011, 09:18:26 PM »

Warning, on 160 m there are just 8 or 10 old f--ts who talk about the same thing every night.  

Not True. DX is alive and well on 160 mtrs. Tune 1820-1840, you have to be able to copy CW.  Cheesy There is also a fair amount of digital operation in the lower part of the band.

(trimmed)

Stan K9IUQ



[Foghorn Leghorn] That was a joke, son, a joke! [/Foghorn Leghorn]

 Cheesy
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KY6R
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« Reply #9 on: August 18, 2011, 09:33:43 PM »

I use a 40M "aluminum" half square, voltage fed through a large Ten Tec variable capacitor and against 64 buried radials. See my QRZ.COM page for a picture.

It has gain on 40M - where its a half square, and works surprisingly well on 160 and 30M for DX-ing, and great for local nets on 75M - not sure if its good for DX-ing on 80M - have been too busy trying to get to 160M DXCC. It does everything I need on the low bands. I use a set of K9AY loops for receive on 160M and 80M.

The ON4UN Lowband Book is an invaluable resource for what you want. I have used a short hatted vertical dipole on 80M to work DXCC, and I used a Cushcraft MA-160V last Winter to work my first 28 DX stations on 160.

You don't need radials for a short hatted vertical dipole - loaded at the center. You will need radials for a vertical. The coils I made for the 80M were quite large, and I think might be hard to do on 160M.

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WB4MDX
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Posts: 10




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« Reply #10 on: October 05, 2011, 02:09:34 PM »

if you can find or make one of these,  jc tri band doublet 160 -40 meter.  fits on 100 foot lot.
this is more NVIS.
see web page
http://www.qsl.net/w1jc/jctriband.htm

second option is a modified inverted 'L' that looks like a square root sign.  need some radials, minimum of 12 about 37 feet long.   Get a 80/40 dipole traps from unadilla. (7.150) you will only need one.  put one half of the 80/40 dipole to the feed point of the inverted 'L'.  then run this up at a slight angle from the vertical portion of the "L".  Make a common mode choke of coax to the feed point then bury to your house. It tunes well 160- 10 meters all bands.  is vertical polarized and has a low angle of radiation.works very well on 40.  I call it a 'square root antenna'. may need an unun to match based on your impedance at the base of the antenna.   the 'L' is 130 feet total length.

if no trees , 43 ft 'eagle one' vertical with radials.


good luck
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WB6BYU
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Posts: 13027




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« Reply #11 on: October 05, 2011, 02:40:00 PM »

What distances do you want to work on 80m and 160m?

A horizontal antenna will be better out to a few hundred miles (further if it is up higher).  Vertical
polarization may be better for longer distances (depending on ground conditions, etc.)

That's the first decision to make.

For horizontal antennas, you can just string an 80m dipole across the 100' space and let the
ends hang down.  I've also designed and built a homebrew loaded dipole (similar to the previous link)
that works on 40m and 160m in the space of a 80m dipole (and could be shortened even further.)
You have to watch the end voltages, however, if you are running power into a shortened antenna.

For vertical antennas, some sort of vertical whip with wire for top loading, or a wire inverted L,
is a good start.  Both will do best with a good ground system.  You'll probably need some sort of
matching network at the base (unless the wire is 1/4 wave long, but even then the impedance
likely will be low unless you have a poor ground) and you may find that a large tapped coil will
serve both tuning and impedance matching if the wire is less than 1/4 wavelength long.  For
example, if you can run a wire up 30' and then horizontally for 100', it will be close to 1/4 wave
resonance on 160m (vertical) and around half a wave on 80m (primarily horizontally polarized.)
By shortening it a bit you can reduce the problems with the high feedpoint impedance on 80m
and match it on 160m with a tapped coil.  You may end up building dedicated matching circuits
for each band and switching between them with a relay.
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NU1O
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Posts: 2603




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« Reply #12 on: October 05, 2011, 02:43:42 PM »

Seems I saw a 160 m vertical in QST in the past 2 years.  Don't remember the issue.

I'm fairly sure Cushcraft (MFJ) makes a 160 meter Ground Plane.

NU1O
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WX7G
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Posts: 5920




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« Reply #13 on: October 05, 2011, 03:30:54 PM »

For 80 and 160 meters I use a screwdriver antenna with a 25' mast making it a 30' base loaded vertical. With 90 radials 25' long the radiation efficiency on 80 meters is 50% and on 160 meters it is 10%. With 1200 watts I have a big signal on 80 meters and while not big on top band it's big enough to work DX and have fun in the contests.
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W3HKK
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Posts: 593




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« Reply #14 on: October 05, 2011, 03:52:31 PM »

do you have a 30 ft or taller tree  or house to hoist an antenna on?  Inverted Ls of .25wavelengths work pretty well.  Even at 25-35 ft apex.

A common feed at ground level with two inverted L's ( one for 80 and one for 160m) work nicely,  even on 60m...so you get 3 for 1.
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