A comparison of software- and hardware-gating techniques appliedto near-field antenna measurements

[摘要] It is well-known that antenna measurements are error prone with respect to reflectionswithin an antenna measurements test facility. The influence on near-field (NF) measurementswith subsequent NF to far-field (FF) transformation can be significantly reduced applyingsoft- or hard-gating techniques. Hard-gating systems are often used in compact range facilitiesemploying fast PIN-diode switches (Hartmann, 2000) whereas soft-gating systems utilize anetwork analyzer to gather frequency samples and eliminate objectionable distortions in thetime-domain by means of Fourier-transformation techniques. Near-field (NF) antenna measurementsare known to be sensitive to various errors concerning the measurement setup as there have tobe mentioned the accuracy of the positioner, the measurement instruments or the quality of theanechoic chamber itself. Two different approaches employing soft- and hard-gating techniques arediscussed with respect to practical applications. Signal generation for the antenna under test (AUT)is implemented using a newly developed hard-gating system based on digital signal synthesis allowinggate-widths of 250 ps to 10 ns. Measurement results obtained from a Yagi-Uda antenna under test (AUT)and a dual polarized open-ended waveguide used as probe antenna are presented for the GSM 1800frequency range.

[学科分类] 电子、光学、磁材料