Jt. Mayhan et al., A TECHNIQUE FOR MEASURING ANTENNA DRIVE PORT IMPEDANCE USING BACKSCATTER DATA, IEEE transactions on antennas and propagation, 42(4), 1994, pp. 526-533
This paper describes a technique for measuring the drive port impedanc
e, denoted Z(D), of an antenna using radar backscatter data. It requir
es only that one has access to the antenna terminal ports, and the abi
lity to attach a known load to the terminals. In the technique describ
ed here, three sets of backscatter data (amplitude and phase) are requ
ired: one with the terminals short-circuited, denoted E(s), one with t
he terminals open-circuited, denoted E(o), and the third with the term
inals loaded with a known resistance R(o), denoted E1. These data are
readily processed to obtain Z(D), according to the simple relationship
defined in (8). An analysis of the effects of the various error sourc
es affecting the value Of Z(D) determined using this technique is also
presented. The utility of the technique is illustrated by measuring Z
(D) for a ''canonical'' body using measured results at L band and UHF
taken on three differing RCS ranges, selected so that they differ in t
he quality of the backscatter measurement over the frequency range und
er consideration.