Wednesday, February 04, 2009

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.


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