160 Meters

What is 160 meters like?
What is the best antenna to use on 160?
Misc 160 meter information
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There's no other amateur band like 160 meters for those that like a challenge (except maybe weak signal work on VHF and above). K1ZM explains in his book DXing on the Edge--The Thrill of 160 Meters:

"While DXing can seem almost routine on 20 or 15 meters, there's no band like 160 to get your adrenaline pumping."

"It still remains the last band where you cannot buy success with your plastic charge card."

Whether you like DXing on CW or ragchewing on SSB and AM, 160 meters is in a class by itself. There's a very good reason why it is still "the Gentleman's Band".


Which is the Best 160m Antenna ?

In a nutshell: vertically-polarized antenna for transmitting, using separate antennas for receiving.

From W8JI on qrz.com:

"The fact is....... an Inverted L with 20 or more radials at least 50 feet and hopefully 100 feet long will absolutely smoke any normal height loop antenna or dipole antenna at nearly any distance on 160 meters. The possible exception is between 20 and 200 miles.

"As a matter of fact a low full wave loop has no gain, any horizontal wire has increased earth induced loss as it is made longer when close to earth.

"Do not make the radials shorter just because you have fewer radials. They really need to be as straight and long as possible, but lengths over 100 feet don't help much. Even 20-30 radials 60 feet long make a fairly good ground.

"Nearly all especially successful stations on 160 use a vertically polarized antenna of some type for transmitting. That's just a fact.

"I have a full size 160 dipole at 300 feet, and it is never really much better than a 1/4 wave vertical at any distance in any direction. As a matter of fact, the dipole is 10-20 dB weaker than the vertical off the dipole ends. The dipole only beats the vertical broadside to the dipole, and then only rarely!! And this is with the dipole 300 feet above ground.

73 Tom"

http://forums.qrz.com/showthread.php?t=260716&highlight=beverage


2014 CQ Worldwide 160 meter contest from Reverse Beacon Network
2014 CQ WW 160 contest on Reverse Beacon Netork




The W0BTU 160 Meter Inverted-L Antenna

I have received a lot of e-mails asking for details about this antenna, and especially the two-capacitor matching network at the base of my inverted-L (which was --much to our surprise-- featured in a ARRL Contest Update newsletter). Here is a brief description and some pictures of our inverted-L antenna and tuner. (This will be organized better someday :-).


Antenna and Elevated Radials
Most of the radiation from an inverted-L is low-angle and vertically-polarized. Depending on the length of the horizontal portion, there is a lesser amount radiated at higher angles. This can be very useful for closer-in communications, and does not seriously detract from the overall performance, even for DX.

I purposely made this inverted-L longer than 1/4λ on 160. Doing so significantly raises the low feedpoint impedance that a 1/4λ inverted-L has (about 17 ohms), and also elevates the point of maximum current. I played with the length in EZNEC and settled on 155' total length.

About 55' is actually vertical. At the bend, the remaining 100' goes through a pulley and gradually slopes down to the east to the end insulator (presently ~20' high) and counterweight through a second pulley, to allow for the trees swaying in the wind. The counterweight is a plastic bucket with drain holes containing enough rocks to tension the antenna to to proper degree.

The two 10' high radials are 132' long. They are oriented N and S; they are not perfectly straight, because I used whatever trees were handy to support them. They are fastened to (but insulated from) the trees by screw-in electric fence insulators. More than two radials would be better; but if they are elevated, you do not need near as many as you would if they were on (or slightly below) the surface of the earth.

This link leads to a post by W4BZ, William Culpepper, a broadcast consulting engineer, showing that his measurements of the efficiency of monopole systems using just four 1/4-wave elevated radials —well-isolated from the earth— was very nearly the same as when using a set of 120 x 1/4-wave buried radials (other things equal)!

The 160 meter inverted-L antenna and elevated radials are connected to the PTFE spark gap insulator (below).

I used 16 gauge THHN insulated stranded copper wire for the antenna and radials, which eventually stretched when a large animal (horse or deer) got caught up in the counterweight. I should have used at least 14 AWG.


Matching L-network (Omega match)
Here is a superior alternative to a tuner that uses a tapped coil. At the base of our 160m inverted-L, we simply used two air variable capacitors in a gasketed plastic ammo box (non-military, from our local hardware store), and it works just great. Tuning is very easy; one capacitor adjusts the feedpoint impedance to match the coax impedance, and the other capacitor adjusts the reactance to zero. The interaction between them was fairly small, until the L portion got stretched longer than 155' by animals.

Variable capacitor values:
I used what I had available, and I forget where the capacitors are actually set.


Choke Balun
This choke is essential to isolate the elevated radials from the coax shield and prevent common-mode current. It also prevents more losses because the coax feedline is laying almost directly on the ground for a long distance. In other words, it forces the RF to stay on the resonant radials and antenna, where it needs to be! Without that choke at the tuner, the outside of the coax shield would act like a non-resonant radial laying on the ground, connected to the resonant radials.

Grounding
The junction of the elevated radials and coax shield is NOT grounded to the earth at the antenna. There's no ground rod except on the bottom electrode of the triple spark gap. A ground rod for lightning protection should be somewhere between the choke balun and the shack entrance for the reason stated above.


Lightning protection
As shown in the photo, there is a triple spark gap (with resistors across them as a static drain) across the antenna, radials/coax shield, and the grounded fence post. It's made from a 3/4" square piece of Teflon® and #12 copper wire. Notice the melted ends from an arc, probably caused by a nearby lightning strike.

The overheated resistor across the top spark gap has since been replaced with a 1.5 megohm 2 watt carbon comp resistor. The bottom spark gap has a 33K 1 watt Ohmite OX resistor across it, as shown in the photo.


Tuning
To quickly adjust the remote tuner, we use a portable MFJ-259B antenna analyzer (with long-life lithium batteries installed!) connected with an 8" length of RG-59/U to the type F coax connector on the tuner housing. Make sure to keep your antenna analyzer up off the ground, resting on a dry 2x4 (or other insulator) while you're adjusting the capacitors, or you'll get inaccurate readings! And neither should you hold it in your hands. Just touch the knobs. Without the common-mode choke, the 259B's case is "hot" with RF from the analyzer and so touching it produces incorrect readings.


A note about current balance on the elevated radials
I never measured the current on them. The current could very well be different on them. That's a project for another day. I have some info kindly sent to me by hams on the Topband reflector explaining this and offering a better way.

A better way would also include more elevated radials than just two.


Performance on 160
We typically don't do near as much on-the-air operating here like some Topbanders do, but we've done enough to know that this antenna works very well, thank you. We've worked a lot of remote DX and all 50 states (including HI, AK, and DC) except two. Much of this was done with just 100 watts on CW, and we've broken more than one DX pileup at that power level.

Using a linear amplifier (from 800 to 1500 watts), we've worked a fair number of other 160 stations in North America on phone; both the E and W coasts, California to Florida to the south, and well into most provinces of Canada. Never tried to work any DX on phone yet.

We almost never use this antenna for receiving, unless the station is fairly close (within a few hundred miles). In almost all cases, we can hear better on our Beverage antennas with a much-improved S/N (signal-to-noise) ratio.


Other bands
Modeling this 160 meter inverted-L in EZNEC shows surprisingly useful patterns and gain on most HF bands above 160. I have also used the antenna with an L-network tuner on 75, 40, and 20 meters with delightful results stateside. The capacitor between the antenna and radial junction is replaced with a tapped coil.

Recently, I've been using this antenna on 75 meters (with a different tuner) to work from SW Missouri into Ohio and the eastern USA, and with wonderful signal reports. See L.B. Cebik's comments about the inverted-L at the end of this article.

Feedline
We use 75 ohm Commscope F-6 (RG-6) quad-aluminum-shield, flooded. All connectors are CATV type F snap-and-seal and filled with silicone dielectric grease. (And yes, Virginia, they DO handle 1500 watts on 160. :-)

50 ohm coax would certainly work; the maximum capacitor values might be a lttle different.

Photos


"The inverted-L is among the very best inexpensive wire field and small backyard antennas for multi-band general communications work. ... it will in all of its simplicity put a usable signal in more places on more bands than almost any other contender, both in the field and in the typical small modern backyard.

"In the end, either the center-fed or the base-fed inverted-L has a number of properties that make it a good candidate for the amateur seeking multi-band general communications in as many directions as possible. The vertical and horizontal components combine to produce moderate gain in most directions. The lobes tend to be fewer and broader --and the nulls shallower-- than they are when using a horizontal doublet. The antennas are not perfect. But they are cheap and relatively easy to build from locally available parts. If they do not merit first place among your antennas, they make very good backup antennas for the main system. However, for many field operations and small backyards, they may be the best choice for a simple, multi-band wire antenna."

L. B. Cebik, from "Straightening Out the Inverted-L", www.cebik.com


I should put all this inverted-L antenna information on its own page someday. The photos certainly ought to be on this page with the text, too.


Please let me know how I can improve this and if you have any questions that are not already answered above or in the photos.






The EZNEC plot below (courtesy of E74AW) shows that you don't need a full-size 1/4 wave vertical to be effective.
Patterns are shown for antennas 12, 16, 20, 30, 40, 50, and 60 meters tall. All have 60 radials, 40 meters long.

Pattern vs. antenna height comparison




160 is the only band I currently operate, using CW around 1825 . It's a great band, and it's not called the "Gentleman's Band" for nothing. You will find that a vertical with a good radial system will work well for DXing while using a separate RX antenna such as a Beverage or a K9AY loop.


--------------------------------

W8JI: "A vertically polarized antenna with a good ground system will work much better than any horizontal antenna. An Inverted L is one of the best ways to make a good transmitting signal, so long as you have a good ground system.

For receiving, a Beverage is simple and easy and very good. If you do not have the room for a beverage, then some small loops will help. Look at K9AY and Flag antennas.

If you cannot have much height, a dipole would be as good or better than an extended zepp or big horizontal loop. Nothing will be as good as an Inverted L or another good vertical for transmitting."

-------------------------------

Unless you want to work only stations very close to you, use a 1/4 wave vertical, an inverted L, or a T antenna with about 60 1/4 wave radials. Use a separate antenna for receiving.

I think if you talk to the people who operate 160, you'll find out that few (if any) of them use a low dipole on that band. Most are using verticals or inverted L antennas. They require a modest radial ground system of about 35 radials 50 feet long. And many use separate antennas for receiving; those with the room use Beverage antennas (or phased short verticals), and those with smaller lots use K9AY loops or similar antennas.

Look at what they use on the AM broadcast band. Without exception, they all use verticals (with an extensive radial system). No AM radio station uses dipoles, horizontal loops, etc.


That's probably an oversimplification, but unless the folks you want to talk to are fairly close, you do really need a low angle of radiation on that band. A dipole is fine on 80 meters on up, but on 160, that's usually not the case.
------------------------------

03-27-2010, W0BTU
Originally Posted by KJ4TIR

Q: I realize that talking on HF depends on a number of factors but in your experience, how far have you been able to reach someone on 160 meters? If you were in my posistion, the foothills of South Carolina, how far do you think I could reach?

A: Adam,
I've been on 160 since January 30, and I've worked 28 countries with a wire thrown over a tree (and two elevated radials). I listen using Beverage rx antennas. I've worked Australia and New Zealand, quite a distance from here. Others have done far better than me.



The Topband Disease

I should warn you about something, though. If you operate 160 meters much, you may get the Topband Disease. ;-)

Perhaps I should now explain the symptoms of the disease. They are as follows:


If these symptoms persist for more than one sunspot cycle (every 11 years), then you should strongly suspect TopBand disease. More info at http://n6tr.jzap.com/tbdisease.html



You would appreciate the 4th or 5th edition of Low Band DXing by ON4UN, John Devoldere, even if you're not interested in working DX.




W0BTU Beverage receiving antennas


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  http://www.w0btu.com/160_meters.html - Last Edited September 27, 2014

 

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