Musings about my bi-square on 40M

Last year my one good strat­e­gy was to treat WPX as a domes­tic con­test. From this local it means hit­ting 40M/​80M pret­ty hard. That said, it is nice to pick up the 6‑pointers (DX QSOs, off-con­ti­nent) and EU on 40M is quite easy from my sta­tion. This year I decid­ed to mod­i­fy my strat­e­gy to cap­i­tal­ize on some easy EU con­tacts. I put up a very sim­ple phased-ver­ti­cal array – 40M bi-square – to see if it would be bet­ter than my trusty E/​W fac­ing G5RV. I think so!

A bi-square is sim­ply a broad­side phased-ver­ti­cal array. The con­struc­tion could­n’t be simpler…a ver­ti­cal ele­ment approx­i­mate­ly 35 feet long, a 70 foot piece of wire con­nect­ing anoth­er ver­ti­cal ele­ment 35 feet long. These are typ­i­cal­ly shown in the ham lit­er­a­ture as an upside-down U either fed in the cor­ner by 50 ohm coax­i­al cable or fed at one end over a ground. There is no rea­son this struc­ture could­n’t be flipped like a right­side-up U. Think of a tra­di­tion­al ver­ti­cal anten­na for 40M over a radi­al field, with one of these radi­als 70′ long with anoth­er 35′ wire ver­ti­cal attached to it. Simple!

I can posi­tion my bi-square so that the broad­side field of radi­a­tion is about 60 degrees. Effec­tive­ly I am point­ed right at the Mediter­ranean. The array is also bi-direc­tion­al so it would favor to New Zealand as well. There is about a 60 degree 3dB beam width which should mean pret­ty good results into South­ern and East­ern Europe/​Northern Africa. On the oth­er side of the world it means good results East­ern Aus­tralian and ZL. Guess what? Exact­ly as I expe­ri­enced. Most of the time I was loud­er into EU on the array over the trusty G5RV. It was nice to have anoth­er 40M antenna.

Will throw some EZNEC+ mod­els up here when I make some time.

Leave a Comment