Topband: Grounded Half Loop Antenna (Cont.)...

[Ed Swynar]

Hello Ink, Bob, Peter, Bob, Dick, Jim, Tom, Javier, David, & Jim,

Many thanks for all of your e-mails...

I hope you don't mind a "group" response like this, but it sure does save wear & tear on the fingers, strain which is better left to manoevering the Vibroplex keyer...! Thanks much for your interest in the grounded half loop for 160, & for sharing your experiences with them (all them POSITIVE, by the way, for those who have never used one!). 

For the uninitiated, there are several references to the aerial: the first, by John Belrose (VE3CV), appeared in the (I believe) May 1982 issue of HAM RADIO, a copy of which I do NOT have. There was also a co-written piece by Belrose & Doug DeMaw in the September 1982 issue of QST, and a short description of it in (I believe) the second installment of the ARRL's ANTENNA COMPENDIUM.

I have two here: the first is oriented north-south, & looks like a long inverted "V" from the horizon (the apex is 50' high on a tower)...the second is oriented east-west, & looks like an inverted "U" strung between two tall trees in the yard. Looking at each antenna separately, the feedpoint is at one end of the wire, right at ground level. There is a ground stake as well at this point, and a 1/4-wave counterpoise wire (comprised of insulated wire, laid atop the ground) for each band, i.e. 160-, 80-, and 40-meters.

The opposite end of the wire is terminated in a ground stake, and it, too, has a 1/4-wave counterpoise wire for each of the three bands. 

The system is fed with RG-62 coax, which is low loss, and which I happened to have an abundance of! A "...quick & dirty" check of the SWR on the "...inverted 'V'" half loop revealed the antenna to be resonant just above the BC band---it was flat across 80-, 15-, and 10-meters. On 20-meters, it was 2:1, and on 40-meters it was 2.25:1. I used the formula 1005 / f (MHz) / 2 for the "V", and found the wire to be too long...for the second "U" loop, I used 468 / f(MHz) which was more accurate. 

It is an EXCELLENT harmonically operated antenna for DX on 40, and, I suspect, 80. I've used both for U.S. QSOs on 160-meters,  but haven't heard any DX there---yet! The Top Band season is still early for me here, but I'm certainly preparing for it.

One thing for sure, it DOES seem a LOT quieter, noise-wise, than other sky-hooks tried here...I guess because of the grounded end...? By NOT grounding the far end, it would become a half-square of sorts (i.e. a 2-element Bobtail) for 80-meters. Also, I believe that as one goes UP in frequency with the end grounded, the thing starts to radiate more off the ends, than in a line opposite to the plane of the wire. BTW, one of the articles quoted the front to side ratio of being only some 3 db, or so---I put the second loop up opposite to the plane of the first more to take advantage of directional characteristics on 40-meters, than anything else...

I guess that about sums it all up. If you have room for an 80-meter half square, then you've already got the fixings for a 160-meter half loop! I guess a relay arrangement at the far end would enable you to take advantage of the features of BOTH of these wonderful wire antennas...

Keep that soldering iron/propane torch warm, & my very

~73!~ Eddy VE3CUI - VE3XZ