Friday, September 22, 2017

Variable coupling loop

So I built a variable coupling loop. I'm not limited to 1/5, 1/4 or 1/3 size coupling loops like in the experiment I did before this way. During my experiment I tried several options and finally get best SWR all bands with a size between 1/3 and 1/4 size of the main loop. Especially on 60m and 40m the SWR is significant better. My advice to loop builders would be just to experiment till you get best results. You might end up with a 1/5 size or any other odd size coupling loop. I think all is depending on the size and material used for the main loop and the pickup loop, the capacitor, the coax and since there is a slight difference between homemade loops there is always a different result.

Actually I was a little surprised with the outcome of this experiment. I use a coupling loop now which is between 1/3 and 1/4 size of the main loop. SWR on 60 till 15m now is below 1:1.6. I think that is a very good result. I consider my magnetic loop ready to go now. Now next thing.....testing on air.

For those that are interested. My magloop consists of 1 box with 500pF varco (which has been described earlier), 3 pieces of PVC tube, A length of 2,7m bamboo 9 75 Ohm coax, a length of 80cm 6mm wire for the coupling loop, 2m RG58 coax.

At the right my 3 portable antennas. First is the MP-1 (in the white tube) with a tripod in the hama bag, at the center there is the magloop and the last one is the PE1BVQ 3 band endfed with 5m Aircell7 coax. The Aircell7 coax is also used for the MP-1 and the endfed needs a tree or mast to hang the wire. The magloop is the only antenna which includes everything to transmit/receive without any extra supports or any other accessories.


  1. Hallo Bas, dat zijn interessante experimenten. Je zou denken dat daar wel formules voor zijn. Maar wat je zegt het hangt ook af van het gebruikte materiaal. 73 Paul PC4T

    1. Theorie is vaak anders als in de praktijk. Er zijn bijvoorbeeld ook formules voor het bouwen van een HB9CV zoals ik die gebruik op 10m. Maar door exeprimenten ben ik op heel andere maten uit gekomen. 73, Bas

  2. KE7TDY - I am working to amass resources needed; in time I'll DX your magloop with my DDRR (flat side) coat hanger - 73 my friend - N1PKE, pro tempora! POST: 10 OCT 17. 09:05Z-UTC.


Thanks for your comment. Bedankt voor je reactie. 73, Bas