I have built a 5ft square shielded mag loop for 160m reception according to
the design in the ARRL antenna book. The description suggests that the
loop has an inductance of 15uh with 520pf necessary to resonate it, with
420pf coming from the distributed capacitance of the coax plus an
additional 100pf.
I have found that I need a lot more than 100pf to resonate (am using a
dual-gang rx capacitor) which suggests the inductance is lower. I have the
loop with the sides horizontal and vertical (rather than diamond shaped)
I have three questions
1) Are there any formulae to estimate the inductance of these square (or
circular) shielded loops?
2) I have some RG62 coax which has a much lower capacitance per foot,
which would appear to give the potential to make a bigger loop. Would
having a bigger loop (eg 7ft per side - which doubles the area) have any
advantages? (eg more gain, or improved signal to noise?) or disadvantages?
3) Can EZNEC-3 model these antennas?
73 Dave G3UEG
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