At 3:52 PM -0800 12/12/02, Dino Darling k6rix wrote:
>When a manufacturer tests antennas on a range, what equipment is
>used? A field strength meter? A spectrum analyzer?
In my first response I neglected to mention something very important:
calibration.
To calibrate measurements of antenna gain, a "standard gain" antenna
is used. This is an antenna whose gain is accurately known --
somehow. Simple examples of standard gain antennas are the microwave
horn and the cylindrical (uniform diameter wire/rod/tube) dipole.
Their gains can be calculated accurately from E-M theory.
The gain of an unknown antenna is determined by comparison with a
standard antenna.
By far the hardest part of antenna gain measurement is dealing with
reflections or scattering from nearby objects/surfaces. The use of a
standard-gain antenna does not solve this problem because the pattern
of the standard-gain antenna is never the same as that of the antenna
under test.
73 de Chuck, W1HIS
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