Greetings Hamish:
Although I am not familiar with the program you are using, what I
think I know about NEC and quads raises these observations:
1] are you observing the maximum segment length criterion
(wavelength/10);
2] using an odd number of wire segments per side (or at least on the
driven side) allows you to place the excitation in the centre of the
side; and
3] I think the drive-point impedance of the antenna as you described
it is considerably greater than 50 Ohms so 2.5:1 at resonance sounds
reasonable.
However, since this is a multi-band antenna, when you "build" the rest
of it, the impedance will change because of the "stub" effect
contributed by the other antenna (if antenna is fed with one co-axial
cable) and/or just the nearness of the other elements, and the
parasitic elements et cetera ...
FWIW;
DaveR
Received on Wed Mar 01 2000 - 06:12:09 EST
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