INVESTIGATION OF SPATIAL AND FREQUENCY FILTERING ANTENNA FOR CONGESTED SPECTRAL SENSING

Abstract

A cascaded spatial-and-frequency-filtering horn antenna is designed to increase sensitivityfor detecting small signals in a congested spectrum environment. Spatial filtering is performed using a corrugated conical horn antenna to achieve 39 dB of separation between the main beam and the peak sidelobe, and to obtain a circularly symmetric radiation pattern. Frequency filtering is accomplished by directly cascading the corrugated conical horn antenna with a bandpass cavity resonator filter. A design method for cascading horn antennas with cavity resonator filters is proposed and validated by matching a conical, corrugated, and pyramidal horn to a third-order cavity filter and also by matching a conical horn antenna to a fifth-order cavity filter. The design method eliminates the need for lengthy optometric tuning using a full-wave electromagnetic (EM) simulator. The conical horn coupled to the third-order filter is then fabricated using stereolithography (SLA) additive manufacturing and copper-plated. Measurements of the frequency filtering response and the radiation pattern of the conical filtering horn antenna are conducted in an anechoic chamber.