On the Ground Loop Antenna
N9MW
KK5JY has done a nice job designing, building and documenting a receive loop antenna that lies on the ground. It is 15 feet on a side and is interfaced with a 9:1 balun to a coax feed to the station. You can see his work at http://www.kk5jy.net/LoG/.
Bruce K3BAT suffers from local noise so he built the antenna and reported good results. I live in a suburban area with normally S7 or better noise on my home brew 37 foot vertical matched with a remote tuner at the base. I built a version to try for myself.
My construction used a full 100 foot roll of number 14 stranded insulated electrical wire purchased at a local home store. The result is an obvious 25 feet per side square. The match is a 1 inch #31 toroid with two turns of number 18 in the primary and 7 turns in the balance output side. It is housed in a 4 inch weather tight electrical box.
Bruce K3BAT suffers from local noise so he built the antenna and reported good results. I live in a suburban area with normally S7 or better noise on my home brew 37 foot vertical matched with a remote tuner at the base. I built a version to try for myself.
My construction used a full 100 foot roll of number 14 stranded insulated electrical wire purchased at a local home store. The result is an obvious 25 feet per side square. The match is a 1 inch #31 toroid with two turns of number 18 in the primary and 7 turns in the balance output side. It is housed in a 4 inch weather tight electrical box.
Below is an Aim4170 scan of the antenna from 1 to 31mHz. The wavy red line is SWR and naturally seems to be an SWR of less that 5:1 from 80 meters up in frequency. In my location the antenna is laying on a dry gravel base. I would expect big differences from either moisture, soil type or if the wire settled into the ground.
I was delighted when I first connected the unit to see strong signals while the noise level was now
showing S-2 or less. It is apparent the unit is not a dummy load. However, the following day while listening to the 40 and 20 meter nets I frequent daily I found closer signals were very good, but longer path signals that normally are very strong were seriously degraded. The antenna obviously favors high elevation angle signals as we might expect. I did not shorten the leg lengths to 15 feet as testing at both 20 and 40 meters should accomplish the same sort of results.
I am not degrading the antenna, only reporting my results compared to my homebrew vertical. The antenna would make a great receive antenna in limited spaces or if low visibility is required. It is an inexpensive afternoon project that might compliment your antenna farm.
showing S-2 or less. It is apparent the unit is not a dummy load. However, the following day while listening to the 40 and 20 meter nets I frequent daily I found closer signals were very good, but longer path signals that normally are very strong were seriously degraded. The antenna obviously favors high elevation angle signals as we might expect. I did not shorten the leg lengths to 15 feet as testing at both 20 and 40 meters should accomplish the same sort of results.
I am not degrading the antenna, only reporting my results compared to my homebrew vertical. The antenna would make a great receive antenna in limited spaces or if low visibility is required. It is an inexpensive afternoon project that might compliment your antenna farm.