Wednesday, February 04, 2009

80 Meter Vertical Experiment;
Bob Raynor N4JTE

I have spent most of my creative antenna energy on 40 meter wires and have had great success with those experiments. HOWEVER, the 40 meter band shuts off like a light switch here in upstate NY a couple of hours after sunset.
Having had a lot of unexpected fun with phased verticals on 40, I researched a way to get the same benefits on 80, as it seems to be the only band available after dark.
Problem is I don’t have two 60ft towers laying around, I know spiderbeam sells them for about $250 but not wanting to spend that much on an “experiment” I was forced into finding a way to use my existing 40ft poles.
I only ventured into phased verticals after figuring out an accurate way to cut feed and phaselines as detailed in previous articles. That epiphany opened a whole new area of experiments for the lower bands. The other revelation that got me going was the value of the Christman method of obtaining correct phase angles using 50ohm coax in place of complicated L/C constants which are beyond my math/circuit board experience.

Ø Utilize 2 available 40ft. pushup poles spaced 1/8 WL apart and achieve the theoretical gain of 3DBD in switched directions.
Ø Incorporate the phaselines as detailed by ON4UN in his bible, “Lowband DX’ing.” Based on the unique qualities of 135 degree phasing.
Ø Top load the 33ft. existing verticals with a (T) loading wire of appropriate length of #18 insulated wire to achieve resonance.
Ø Cut (2) phase lines at 157 degrees and (1) delay line at 39 degrees,
Ø Wire up 12v DPDT relay to achieve reverse capability.
Ø Wait for snow/ice temperature to go above 18 degrees!

My understanding of shortened verticals tells me that any loading system should be as close to the top as possible, I queried my fellow Elmers on Eham and and realized pretty early on that a coil at the base would be far from ideal. Adding wire at the top is the way to go and my lazy alternative of adding bottom fed coils was rejected.
If ON4UN is correct, and he usually is, he tells us that if the vertical is not less than 66% of 1/4WL height, you will have close to the same gain and front to back as that of a full size antenna array. You will be handed a narrow bandwidth, but that can be a matter of choice when designing the antenna and the use of a matching network at the antennas will expand your range of operation.

The first step was to top load one of the existing 40 meter verticals and achieve resonance at 3.7 megs. I cut a piece of 18 gauge insulated wire to 30 ft. and exposed the center and attached it to the vertical 33ft. wire. Before raising it back up I attached some masonry string to the ends to facilitate tying off in opposite sloping directions.

With 2 raised radials, resonance was above my target frequency so I lengthened each end of the top loading wire until I got close enough. I checked resonance, lowest swr, at the radio instead of antenna base because I don’t trust the MFJ at low frequencies due the fact we have a local am/fm station less than 1 mile away that could possibly skew the readings. A lot more trudging in the snow but worth the effort as this way the whole “system” is being measured.
The sequence was repeated on the second vertical while taking pains to keep the top loading wires parallel to the other vertical’s. Not sure why, but my instincts tell me that the mutual coupling of 33ft. should be maintained on the vertical and T wires.
I rechecked the resonance of the first vertical and noticed a slight increase in the resonant frequency. I could probably have spent a few more hours freezing my butt off to fine tune it, but I’ll save that chore for spring!

I have existing poles in an East/West orientation as it seems the best compromise for DX and stateside contacts from my home here in upstate NY. I believe the verticals are fairly broad, somewhere around 135 degrees so that’s where they going to stay for this experiment.
The relay was wired up with short alligator leads as detailed in previous articles again taking care to maintain polarity. The phase line of 39 degrees was cut out of 50 ohm coax and ended up around 15ft. The 157 degree feedlines ended up around 63ft.each.
I never rely on published VF except to get a general idea of approximate length then I use the MFJ to get the exact readings, also spelled out in previous articles.
Not shown for clarity is the feedline to the shack nor the 12volt wire from power supply in shack, 3amp Radioshack.

Remember when I said I would wait till Spring before getting both verticals exactly frequency matched? Well, preliminary testing as built was not outstanding. One antenna showed a 1.2 to one swr and the other was 1.8 to one, impossible to switch directions effectively. So before continuing on air testing, I put on the Carharts and ventured back out into the 13 degree weather to make both antennas resonant on 3.700 by adjusting the top loading wire lengths, not fun in these temperatures! That mission accomplished, I thawed out and was rewarded with a 1.2 on each wire in both directions, no tuner needed for a change.
My comparison antenna is a 40 meter EDZ at 60 ft and very close to resonance at 3.700
Did the verticals work ? Absolutely, I got significantly better reports, 3 to5 S units from various European stations as compared to the dipole and I had the same results with CA. contacts. This antenna works well but is very narrow banded. I did not lose too much in the 400 to 1000 mile range probably due to the sloping top wires. The horizontal component was not completely cancelled out as would be the case with flat top loading.

Final Thoughts;
This antenna will maximize your signal on 80 in a relatively small footprint with a very small investment as compared to store bought shortened miracle antennas. I probably will invest in a couple of 60ft. poles and eliminate the time consuming top loading and resultant narrow bandwidth. But for now I will be happy with doubling my ERP in opposite directions. And while the snow keeps burying all the mess I made in the backyard, I will be reading ON4UN’s book by the fireplace for the 5th time, looking for the next big idea. Maybe phased inverted L’s for 160 meters! Stay tuned.

Tnx for reading,
Poor Man’s 40 Meter 4 Square;
Submitted by N4JTE.

A few months ago I submitted an article titled; “Verticals; Got 2 ?”, which basically presented a simple, yet effective, way to phase a couple of vertical wires and make them reversible while achieving a relative gain of 3dbd and a surprising degree of front to back capability based on ON4UN’s design/ modeling specifications.
It worked very well considering I miscut the phase/ feedlines due to my screwed up formula at the time.
As luck/ misfortune, would have it, I had to head back to Fl. for a construction contract and could not continue that experiment.
Now that I am back in upstate N.Y. I decided to rebuild the two ele phased verticals with the corrected feedline and phase lines lengths, in the snow and freezing rain of course. It worked extremely well with significant front to back etc. so I decided to try another phased pair in the opposite directions and hopefully achieve a “ Poor man’s 40 meter 4 Square”

First; a quick recap from the previous article which detailed how to accurately cut feedline lengths by using the MFJ with a parallel 50 ohm load based on the fact that a true 90 W/L degree line will exhibit the lowest swr with the end shorted of a 50 ohm coax. At lowest swr/ reactance the frequency displays the 90 degree frequency under test, Simply shorten coax carefully in small increments until you are at the degree/ frequency you need.

Formula for feedline length based on freq. readout on MFJ.
84/90= 7.185/X = 7.698
71/90= 7.185/X = 9.107. Very handy way to cut the four 84 degree feedlines and the two 71 degree delay lines required to feed each pair of verticals correctly and achieve the gain and reversibility as detailed by ON4UN.
My antennas are designed for 7.185 so my feedlines had to be resonant at 7.698/ 21 ft. and the delay line needed to be at 9.107/ 15 ft for the RG58 coax. Far enough off of the published VF to make this technique the way to go if you want it accurate.

I am fully aware that what I am going to describe here is not a true 4 square in the classical format and this experiment does not take advantage of the inherent parasitical interplay of 4 verticals at the corners of thirty three foot sides on the square. However I do not have an extra $400 for the hybrid phase system nor the required real estate for the classical design.

Rather than make this a” how to build” article, I will give the basics and welcome any further questions via email.

1; The NE/SW antenna is (2) 33 ft. long insulated # 12 wires vertically supported by 2 fiberglass push up masts at 40 ft. This ends up with the raised radials about 6 ft. high. I used 2 radials on each antenna for experimental/ laziness purposes. The distance between poles is 33ft. ¼ W/l.

2; The E/W antenna pair was strung from a catenary string between the available maple tree and an old rohn push up with the top part using about 16 ft of fiberglass to hopefully avoid any interaction with the two 33ft wires hanging down. Also at 40 ft high to allow for the two raised radials.

Both pairs of verticals are 33 ft. apart and fed with identical feed systems utilizing 84 degree feedlines from the relays and a 71 degree phase line inserted between the feedlines. This setup will obviously need two separate feedlines to the relays. You can however run the same 12v supply in parallel without affecting the patterns, I think !
Make all antenna wire lengths the same and while I have had excellent success with 2 radials of equal length, others might want to add more if space allows and adjust for better apparent matching. Do try to keep radials from being parallel to each other as they will skew pattern and loading.

Feed System;

I soldered short alligator clips to all the stubs for ease of connection in the field. The addition of 71 degree delay line adds the reverse ability to the two elements and the force feeding as per Mr. Christman makes for an easy method for equalizing voltage and impedance at each element. The addition of 12 volts to the relay instantly reverses direction, nice !

To achieve the 4 direction capability I fed each pair of verticals at the relay with RG13 which was brought into the shack and connected to the coax 1 direct and coax 2 direct of my MFJ tuner
I ended up with about a 1 to 8 swr on both pair of antennas, not bad and not unexpected as my radial layout is pretty lame and temporary for testing purposes. With relays off I dedicated one array to the Southwest and the other array due East. With a little practice it became second nature to flick on the power and change directions. I put the feedlines thru the tuner and got down to 1.2 to one for both antennas with additional tuning, kinda split the difference. I am running an AL80B thru this setup so it was important to match up a little better.
Also; the relays have no problem at 600 watts..

On Air Results;

Well I must admit that my testing on 40 has been limited to mostly daytime due to non existent nighttime prop here in upstate N.Y. past 6pm since returning 2 weeks ago from Fl. but on air testing around the Country and Canada was very rewarding. The 4 to 7, S units front to back and reported signal strength differences in 4 directions is well worth the effort. I expect when 40 comes out of its nighttime coma here I will see more dramatic results.
I still have a 40 EDZ at 65 ft. which was used for a reference in similar directions with the appropriate phased verticals and they certainly held their own and then some. My EDZ is now my 75 antenna, don’t need it on 40.

Final Comments;

As mentioned, I did not overly detail the whole construction process here as I would hope that others will explore the concepts presented on phased verticals and improve and adapt the design to their own needs.
If anyone needs more details; email me at

Regards to all.