[TenTec] New Jupiter on its Way _ A Few Questions

[Stuart Rohre]

Based on an article on loaded antennas in the latest QEX magazine from 
ARRL, I would say a magnetic loop, if larger than 0.1 wavelength 
diameter, might have either the same signal as a loaded dipole, (short 
dipoles as I imagine you mean), or the magnetic loop will have BETTER 
signal to noise on receive, which is very valuable in the indoor 
environment.  Gain in the receive, or low noise, may be better than more 
signal on transmit.

Both types of antennas would give better results if placed in an 
unobstructed attic, (wood house), or placed at least, on the edge of a 
roof.  A larger than 0.1 wave loop could be hidden in a fenced back 
yard, and even put on a pulley system that would raise it up to hang in 
a back yard tree for after dark operations.

Being indoors as now; you are in a cage or cobweb of electric wires, 
possible metal plaster lath, and obstructions from large appliances on 
the other side of a wall.  You are subject to causing TVI to electronics 
inside the home at least, or next door, or the next apartment.

Of all the indoor operating means, the loop offers the best results, 
especially on receive, if shielded, and made of low loss construction.

Use large diameter loop material and low loss connections.
One of the best loop designs for HF used copper tubing of 1 inch 
diameter or larger, and was octagon shaped, because angled fittings were 
available.  The joints were silver soldered for lowest loss.

The capacitors on the end can be trombone type made from sliding copper 
pipes, with teflon tape as spacer and insulation.  Or use surplus vacuum 
variables which turn up at swap meets.  Or even large metal air spaced 
variables.  while you might spend some money up front on material, 
(pipe) and capacitors, those parts and the loop can be used for ANY 
future locations, Field Days, or even mobile on a van.

Locally, Bob, WB5AOH had one on his van that worked HF great on low 
bands like 40 and 75.  He would still have it but for a low hanging tree 
limb!  (With big mobile antennas back in bicycle days, I learned you 
have to drive both the vehicle and the antenna!)

-Stuart Rohre
K5KVH