ON THE DEVELOPMENT OF 18-45 GHZ ANTENNAS FOR TOWED DECOYS AND SUITABILITY THEREOF FOR FAR-FIELD AND NEAR-FIELD MEASUREMENTS

摘要

The development of a wideband, high-power capable 18-45 GHz quad-ridge horn antenna for a small towed decoy platform is discussed. Similarity between the system-driven antenna specifications and typical requirements for gain and probe standards in antenna measurements (that is, mechanical rigidity, null-free forward-hemisphere patterns, wide bandwidth, impedance match, polarization purity) is used to assess the quad-ridge horn as an alternative probe antenna to the typical open-ended rectangular waveguide probe for measurements of broadband, broad-beam antennas. Suitability for the spherical near-field measurements is evaluated through the finite element-based full-wave simulations and measurements using the in-house NSI 700S-30 system. Comparison with the near-field measurements using standard rectangular waveguide probes operating in 18-26.5 GHz, 26.5-40 GHz, and 33-50 GHz ranges is used to evaluate the quality of the data obtained (both amplitude and phase) as well as the overall time and labor needed to complete the measurements. It is found that, for AUTs subtending a sufficiently small solid angle of the probe's field of view, the discussed antenna represents an alternative to typical OEWG probes for 18-45 GHz measurements.