A novel low RCS microstrip antenna array using thin and wideband radar absorbing structure based on embedded passives resistors

Abstract

A novel low radar cross section (RCS) microstrip patch antenna array (1 × 4) (MSPAA) is reported in this paper. A thin and wideband radar absorber (RA) based on a single octagonal loop (SOL) resistive frequency selective surface (FSS) is designed for realizing out-of-band RCS reduction of the MSPAA from 6.2 GHz to 18 GHz. The RA is designed for −15 dB reflectivity from 6.2 GHz to 18 GHz. Embedded Passives (EP) resistors are used for implementing the resistors as integral to the substrate with no soldering at all which results in a quantum improvement in reliability. Full wave analysis of the low RCS MSPAA with the RA is carried out using HFSS. RCS measurements are performed, and an RCS reduction of 6 to 18 dB is attained compared to the reference antenna array over a wide band from 6 GHz to 18 GHz, with no degradation in VSWR and gain of the antenna array. The thin and wideband RA with its low weight and flight worthy constituent materials can be applied independently as skins of a stealthy UAV configured primarily for low RCS with external shaping, and the proposed antenna array can be used without modifications, as a low RCS conformal antenna structure.