160 Meter High Noon Propagation Test Saturday or Sunday ?

[WD8BIL]

I've got a perverted L up now.

I get good reports in the later evenings from Central New York to the east coast. But nothing to write home about.

Problem is, it don't hear worth a darn. Way too noisy. A seperate receive antenna (beverage, mag loop, EWE ...) is in order.

Another thing to consider about Ls is the electrical length of the vertical section. To be real effective I found anything below 45 degrees electrical length is probably not worthwhile if there's another possiblity. The feedpoint impedence gets real low and the horizontal (high angle) componant does more harm than good.

On the other hand, you do get more low angle vertical from it than you would from a low dipole. And, they are easy to play around with in a confined space. It definetly falls in the "compromise antenna" catagory.

[K1JJ]

I agree with Bud suggesting it's possibly a compromise situation....  More to consider:

In a small, closely packed residential area, a 160M  inverted L or vertical is a tough game to pull off. To offer a better low angle component than a dipole, they require a radial field that extends at least as far as a dipole's space - and needs 360 degrees of room. This is for pure I/R efficiency. In addition, if the useful LOW angles are expected to even get out of the area, the surrounding houses/ elec wiring/plumbing, etc and other obstructions need to be clear for at least 300' or else these low angles are distorted and attenuated. Lots of coupling.  Also, the vertically polarized noise picked up from surrounding neighborhood appliances/computers, power lines, etc can negate the advantages over a dipole.  RFI can occur more easily too.

ie, To BEAT a simple 160M dipole at 60' high, they need a lot of radial work, and more importantly, they need favorable placement in the clear, much more than a dipole needs, else it will be a wash between the two systems at best. [sigh]


T

[WD8BIL]

Well said Tom. I even read it all instead of drooling at Mrs. VU.

First chance I get the the perverted L is coming down. To be replaced with a dipole.
It would be interesting tho to put up a loaded dipolio of say 120' overall length and see what it does in comparison. Might give some useful info to those locked into a small lot.

Hmmm..........
 

[Jim, W5JO]

Given my limitations of tall supports, I chose the L.  Have 44 ft. vertical (not enough) but it works fine for me.  When I say fine, I mean I talk to those I hear and many I can't give me good reports.  This is out to 12-1500 miles.  I also do not have trouble close in to my station. 

My vetical is about 50 ft. from the house and the horizontal (~120 ft) is close to my 75 meter dipole.  Given we all have some sort of limitations we have to make what we can put up work.  In my case the L is the best since I can't get a dipole more than 40 ft. up.  My only advantage is that I live in a rural area and not subject to all the noise a subruban location has. 

The other night the band was iffy at best and a guy out in AZ came on with a folded unipole matched to frequency.  I was in with a group who were using different lenght vertical radiators from 193 ft to 93 ft and one had a full wave horizontal loop at 60 ft.  My report was right in there with all them.

I have poor ground beneath the antenna and only about 16 full size radials.  There are about 15 other radials of various length beneth it.  What it come down to is we design what will fit and then make it work.  The other night I heard WB3HUZ with a fair signal, but the transmitter was cold.  I couldn't get on in time to catch HUZ, but am sure if I had been ready, we could have talked some.

I sure wish I had a flat field to put up a 1/4 wave vertical with 60 raidals under it, but am satisfied with the antenna.  It took some work to get the noise down and the radials lay over very uneven ground, but it works.  Should 160 ever settle down, I am sure I could work most of you back east.  I have my fingers crossed.

[Chuck_WA4HHG]

Came home from work a little early today, 1930 UTC.  Worked KC2DMC (up in the Catskills) on 160 AM.  Gave hime a 4-3, he was PW although copyable here in beautiful Chesapeake, VA.

We going to try any tests tomorrow?

Chuck

[Tom WA3KLR]

Hi Chuck,

No more high noon 160 propagation tests for now.  The next one scheduled is the High Noon 160 Meter Summer Solstice Test for July 1 and 2, 1 week after Field Day.

The band has been proven to be quite useable by the tests done last weekend; at least 300 miles range at the worst part of the day. 

The point is let's all get on and QSO.  I will set up on 1885 kHz. AM now.

[Steve - WB3HUZ]

Some thoughts on the Inverted L.

Take a look at the modeling. You will see, even a compromise L will beat a dipole at lower take-off angles (which is the best reason for using an L in the first place). If your main objective is to QSO with the homies within 200-300 miles, you'd be better off with a dipole, even a short one.

If the vertical section becomes too long, and the horizontal radiation too great, consider a T antenna. No matter how short the vertical section, if the horizontal portion is symmetrical, most of the horizontal radiation will be cancelled.

I used a T about five years ago. When working station at distances greater than 400-500 miles out, the T beat a 50 foot high dipole, usually significantly. The most dramatic was when I worked a station in Minnesota. On the dipole, the MN station couldn't even hear me. With the T, I was 5-by. The T only had 8 radials (about half were elevated 6-8 feet off the ground). The vertical section of the T was only 50 feet.

A separate receiving antenna is generally must, when using an L or T. Having a specialized receive antenna is a good idea on 160, even if you are using a dipole. I used a small tuned loop made out of RG-6 and tuned with a broadcast variable. It was cheap, easy to make, and worked well.

Hope to work you on 160 sometime Jim. If you'd like to make a sked, let me know. I haven't worked very many stations out west on 160 this year.

[WA1GFZ]

Steve, How long was the flat top section of yourT?
One could use a 75 meter dipole as a t if fed with open wire line.

[Steve - WB3HUZ]

The flat-top section was about 180 feet. Each end of the horizontal section hung down vertically for 30 feet, so the actual horizontal portion was 120 feet. The T was, in fact, my open-wire fed dipole, with the feeders tied together and fed against ground/radials. A 75 meter dipole could be deployed similarly.

[W2VW]

A separate receiving antenna is generally must, when using an L or T. Having a specialized receive antenna is a good idea on 160, even if you are using a dipole. I used a small tuned loop made out of RG-6 and tuned with a broadcast variable. It was cheap, easy to make, and worked well.

Is this ant. on the www someplace? Just want to take a look at it. The loop here works like gangbusters on the broadcast band but I want to get it to transmit on 160 just as an exercise.

[Steve - WB3HUZ]

Which ant? The loop. It's receive only. I guess you could use it for TX, but you'd be PW!

[W2VW]

Which ant? The loop. It's receive only. I guess you could use it for TX, but you'd be PW!

Yes, the loop. I am used to being PW.

[Steve - WB3HUZ]

It was more or less the same as the one shown below. Mine may have been 3 or 4 feet on a side.



Full size
http://www.amwindow.org/misc/jpg/loopschematic1a.jpg

[Steve - WB3HUZ]

Another option, posted a few years ago by Bill, KD0HG.

Open air loops for BCB/160/80M are awfully easy to implement.

Build a a + shaped frame out of two wooden crossarms with some sort of weighted base attached to the bottom of the vertical piece.
You will need to attach a broadcast variable capacitor near the bottom, just above the base.
For BCB use about 6T of wire around the loop, for 160 maybe 3T and for 80 about 2T. Depends on the diameter of the loop...One to two feet. The wire ends of the loop connect to the air variable. Use maybe #18 insulated solid bell wire and glue, staple it to, or thread it through holes drilled in the frame. Add a 2nd, 1 turn loop inside the tuned one. Its ends attach to the feedline going to your receiver.

That's pretty much it. There will be a pronounced signal peak as the tuning cap goes through resonance. Adjust loop turns accordingly if resonance is found at either extreme of cap travel.

Of course, relative RF levels are less than with the use of a transmitting antenna, but you will be able to hear anything you can on the big antena, but most of the time better with proper orientation. The loop had a bi-directional pattern with some awfully deep nulls and seems pretty much unaffected by nearby objects, metal or otherwise.

The one I built for the BCB is able to just about completely null out a nearby 10 KW AM station letting me hear the skywave and selective fading even during mid-day. Pretty cool. Very sharp nulls. On 80 you will need to not only rotate the azimuth of the loop, but it's tilt as well for best results depending on a signal's angle of arrival.

Overall pickup is not too bad, providing adequate signals on most 'modern' hollow-state receivers with a hot front end. Decent, very listenable signals can be received from the higher-powered AM BCB stations at even 300+ mile distances during the day. From Chicago, for example, where I used one 25 years ago I was able to receive WJR/Detroit, WWWWE in Cleveland, WLW/Cincinatti, 1040/Des Moines, during the day, most any day.
By comparison, I couldn't even begin to hear the same stations on my 125'long wire.

The thing is also helpful for discriminating against local QRN and power line noise and some thunderstorms.

[W2VW]

TNX. Mine is very similar to the first one but matching needs work.