The design frequency, the feedpoint impedance, will be between 80 and 150 ohms. Coax fed loops will usually have an SWR between 2:1 and 3:1. You may feed this antenna with a 4:1 balun. If the loop is in the shape of square or large rectangle, the SWR can be below 2:1
http://www.radioworks.com/nloop.html
It uses one, six foot square, six turn loop, and is aperiodic in nature, covering the frequency range 50KHz - 5000KHz.
http://www.zen22142.zen.co.uk/Circuits/rf/6x6loop.htm
Wound on a3-foot length of PVC pipe, the long Loopstick antenna was an experiment to try to improve AM radio reception without using a long wire or ground. It works fairly well and greatly improved reception of a weak station130 miles away. A longer rod a
http://ourworld.compuserve.com/homepages/Bill_Bowden/page2.htm#tuner.gif
Wound on a 3 foot length of PVC pipe, the long loopstick antenna was an experiment to try to improve AM radio reception without using a long wire or ground. It works fairly well and greatly improved reception of a weak station 130 miles away.
http://ourworld.compuserve.com/homepages/Bill_Bowden/page2.htm
able to produce some nulls up to 40 db on S Meter.
http://www.mindspring.com/~brucec/loop2.htm
Loop antennas offer many advantages for LowFER reception. They're compact, don't need to be high and in the clear, and their directional characteristics can be used to null out local noise or strong interfering signals.
http://www.lwca.org/library/articles/k0lr/lf-loops.htm
All ATL-3 loop windings are centre tapped and balanced w.r.t. their amplifier/receiver chassis ground, and therefore electric field interference pick up tends to self cancel.
http://www.zen22142.zen.co.uk/Circuits/rf/atl3.htm