Topband: RX 4 SQ Phasing

[Larry Molitor]

Dennis, W0JX, is nearly correct but didn't go far enough.

In the last few years I've had up several Hi-Z two element arrays, a Hi-Z 4-sq, and a Hi-Z 2-3 array. They all exhibit the same characteristics. Depending on the element spacing used, the upper frequency limit may be over 7 MHz. For instance the 4-sq at 50 foot on a side worked nearly as well as my full size 40 meter 4-sq. On the other hand, the 2 element array at 60 foot spacing is worthless on 40 meters.

However, the lower frequency limit of usefulness extends WAY below the AM broadcast band. For example I currently use a two element Hi-Z array with 60 foot spacing and can see as much as 30 dB F/B as low as 150 kHz!. The 4-sq worked well as low as 350 kHz, maybe lower, never checked. The two element (and the 2-3 array) show outstanding performance on the new 630 meter band as well as NAVTEX and NDB frequencies.

Be aware that due to the long wave lengths and and the fact that a 70 foot tower with yagis on top is usually resonant in the BC band, when tuning around you may find frequencies that show little or no F/B. 

Pay attention to "arrival angle" as well. High angle signals will show little or no F/B and possibly even reversed direction.

The best way to test your array to see if it is actually working correctly is to look at local groundwave signals because the "arrival angle" of DX signals is usually unknown. It's pretty easy to tune local AM stations and check F/B when you know that the array will work down there about the same as on 160.

FWIW, the Flag, as built to K6SE's original spec also performs quite well as low as 100 kHz.

73, Larry - W7IUV


>________________________________
> From: Dennis W0JX <w0jx at yahoo.com>
> As far as phasing relationships, the HiZ antenna system uses "Cross Fire" phasing, an approach that maintains a balanced
relationship in the delay lines over at least a 2 to 1 frequency range, so that the system works very well on 160 and 80 meters.
>