Summary -- Trends in antenna measurements

Abstract

the instrumentation for antenna measurements has kept pace to provide increased capability for the measurement of important antenna characteristics. Pattern recorders, receivers, signal sources and positioners have been developed to provide greater dynamic range, improved accuracy of measurements and ease of operator use. Economic considerations and the measurement demands created by new antenna techniques and severe performance measurements. These trends can be catagorized as follows:specifications have brought about some definite new trends in antennaAs antenna technology has advanced over the past twenty years, 1) Automation to reduce time and manpower requirements2) Indoor measurements on compact or near field ranges for increasingly complex measurements;to eliminate real estate requirements and permit 3 ) Greater stability of signal sources and receivers and operation in inclement weather; precision in positioners for verification of severe antenna specifications; mental effects, 4) M e a s u r e m m t s of antennas a s functions of environautomated anteMa measurement system. A l l functions of the ment are automated using programmable instrumentation and softsystem, including positioning, frequency control and data measureware designed specifically for the acquisitions analysis and display listed in Table 1. of antenna data. Tpical measurement performance capability is Figure 1 shows a block diagram of a commercially available The proliferation of m i c r o p r o c e s s o r s i s a l s o having a significant impact on antenna measurement instrumentation, increasing both capability and flexibility. A new generation of instruments and measurement systems will result.The compact range which was originally developed at Georgia Tech, Reference 1. is a system that is now available off the shelf.feet. The basic principle of a compact range is to generate a Measurements can be made indoors on antennas as large as 5 to 6 uniform plane wave, using a very accurately machined section of a paraboloidal reflector.A s shown in Figure 2, serrations on the edges of the reflector reduce effects of edge diffraction. Reference 2 gives plots of amplitude and phase in the active zone to indicate the uniformity of the plane wave illumination. Antenna measurements up to 30 GHz have been made on compact ranges with excellent results.academic and research institutions for many y e a r s (e.g. Ref. 3 and 4). Near field measurement techniques have been investigated by 268