A Simple Loop Aerial for 160/80
The idea of this 160/80mtr aerial is that the tuning and matching components are kept out of the weather and within reach of the operator. If this sort of arrangement would fit your situation it's worth a try.
The loop is made of thick cable, satellite coax is good because there's plenty of copper in the braid.
I mounted the matching and tuning components right inside the window in an ice-cream carton and drilled holes in the glass with a ceramic tile drill to bring in the loop ends. This keeps the Q nice and high. The antenna should tune from 1.8 to about 5MHz with 50ft (16Mtrs) of cable in the loop.
The toroid transformer is wound on a red/yellow T130-8/90 type dust-iron core with four turns of UR43 coax. The braid is used as one winding and the inner as the other. Various sorts of cores are available of this size and colour, but they will not all necessarily work. Use Micrometals T200-8/90 toroids (yellow/red). More common T200-2 cores (red) should work but I haven't tried them.
The loop was installed at G4BGZ who has very little antenna space. He has worked all over the UK on 160 SSB and into North America on 80 SSB. I have also used it as a portable antenna when on holiday in places with little space. Last May I used it in Cornwall with the apex supported by a 20 foot portable mast taped to a line prop! (see photo ). The ice-cream carton was taped to the other line prop at the far corner of the loop. I worked into Fort William area on 160 and all over the place on 80 using 100 Watts so it is a reproduceable design.
The loop in action in Cornwall, not too far from the cottage wall but working OK.
News from G0POS in Kent. He's made a square version which seems to work well. Any other successes? Let me know!
Reg, G4FGQ has written programs for calculating the efficiency of magnetic loops. The zip file here extracts to two exe files, rjeloop1.exe and rjeloop2.exe. They both work in a similar way but loop1 does regular square, circular and triangular loops and loop2 does rectangular loops. G4FGQ loop calculators.
I'm sure Reg would welcome any comments on the programs... Visit his new web site for more programs, see the links in the Shack.
Incidentally, Reg recommends using a coupling loop of about 1mtr "diameter" at the corner of the loop, instead of my incomprehensible transformer arrangement! The only snag I can see is that it would need four holes through the window but, if that isn't a problem, give it a try!
Back to the shack