Great site for basic loop information.
- Thanks for the link to a good loop antenna article. I have been using the rectangular and square loop calculators at http://emclab.mst.edu/inductance/index.html for years. Very helpful. I wish I had room to make full use of the rotation and tilt features of the 3 or 4 foot box loop. Sharp, deep nulls would be useful. I have just completed a 42 inch by 58 inch rectangular loop with a five turn litz wire tuned winding and a one turn AWG #20 solid wire winding driving my ten Tec RX320D receiver. I have not found it worthwhile to leave space between turns, but the space between the windings is important. A relatively small distributed capacitance is not a problem for me, but I do like to maximize winding Q so I use "slot" windings, that is a winding with the wire pushed into a slot at each of the 4 cross arm ends. Keep in mind also that with litz wire you have to avoid sharp bends - I keep the bend radius for 100/44 litz at or above 1/4 inch. With a five turn slot winding and a one turn turn driver winding I can use LTSPICE IV to model the antenna performance. The model requires values for the coupling coefficient k which can be calculated using equations from F. E. Terman's Radio Engineers' Handbook, 1943. And this is much easier if each winding lies in one plane or nearly so. I have not been able to find anything more recent to relate k to winding separation. I find there is a functional relationship between k and antenna Q, so I maximize Q(hopefully improving the signal+noise/noise ratio thereby).
My new 42 inch X 58 inch loop is located between a wooden bookcase and a wall(there is, I think house wiring inside that wall). My long range goal is to use this loop and my Ten Tec Rx320D to begin exploring WSPR-15 in the new 472 khz - 479 kHz amateur band. I live and operate in a noisy environment, but a good, high Q loop antenna will help. Thanks again for the article. Bill Young WD5HOH
Date: Sun, 21 Apr 2013 19:28:26 -0700
Subject: [loopantennas] Great site for basic loop information.