Antenna Calculators
The best part about Amateur Radio is assembling your own antennas from scratch. It's cheaper, and likely works better than a commercial equivalent for the same band. If Mother Nature decides to damage your antenna, (and she will... just give it time...), then repairs / rebuilding is just as cheap as the first time.
How long should it be? Figure it out below:
Wavelength Calculator
Ohm's Law
Enter any two values:
How to mount and feed.
Horizontal or vertical polarization of an cubical QUAD-Antenna is determined by placement of the feed point (feed gap on the driven element) - Parasitic elements need to be mounted in the same orientation as the driven element. If tuning gap is present on the parasitic elements, doesn't the placement of this gap effect the polarization. Feed line is made out of standard coaxial cable (RG8/RG58) 50ohm unbalanced, to attach this feed line to the balanced drive element (Quad loop) without proper matching is not advisable, instead use an 1:1 balun
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Gain vs Spacing
The gain of an antenna with parasitic elements varies with the spacing and tuning of the elements, and thus for any given spacing there is a tuning condition that will give maximum gain this spacing. The maximum front to back ratio seldom, if ever occurs at the same condition that gives maximum forward gain. The impedance of the driven element also varies with the tuning and spacing, and thus the antenna system must be tuned to its final condition before the match between the coax and the antenna can be completed. However, the tuning and matching may interlock to some extent, and it is usually necessary to run through the adjustments several times to insure that the best possible tuning has been obtained.
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