Analysis of Transmission Loss and Boresight Error of a Curved FSS Radome-Enclosed Antenna

Hokeun Shin,Daeyeong Yoon,Dong-Yeop Na,Yong Bae Park

doi:10.1109/access.2021.3094526

Abstract

In this paper, we numerically study a curved frequency selective surface (FSS) radome, which encloses a waveguide slot array antenna operating at 10GHz, using the ray tracing technique and flat model. The transmission loss (TL) and boresight error (BSE) are calculated for various degrees of freedom, such as elevation and azimuth angular scanning or gimbal systems of array antennas to examine the electromagnetic properties of the curved FSS radome. Our calculations of radiation patterns, TL, and BSE for a multi-layered dielectric radome are compared with those of a commercial EM solver for validation. Importantly, we quantify phase distortions, incurred by the curved FSS radome, using the insertion phase delay (IPD) of transmitted fields on the radome surface. Thereby, we demonstrate that the BSEs strongly depend on (1) the spatial distribution of phase distortions on the radome surface and (2) their average level. The present method is highly suited for analyzing radomes with arbitrary surface patterns inserted.

Highlights

An airborne radome protects an enclosed antenna against adverse external environments, primarily looking streamlined to meet the aerodynamic requirements [1]. It may significantly alter the original specification of the antenna’s radiation: transmission loss (TL) and insertion phase delay (IPD) are caused when electromagnetic (EM) waves passing through the radome wall [1, 2], and phase distortions are incurred by IPDs, leading to boresight error (BSE) along with the asymmetric radome geometry
The frequency selective surface (FSS) layer can be represented by a shunt complex admittance in the equivalent transmission line model; the ohmic loss occurs owing to the real part of the admittance [34, 35]
We have confirmed that the BSE of the FSS radome were smaller than those of the dielectric radome because the phase distortion of the FSS flat model were smaller than those of the dielectric flat model in the incident angle range

Summary

Introduction

An airborne radome protects an enclosed antenna against adverse external environments, primarily looking streamlined to meet the aerodynamic requirements [1] It may significantly alter the original specification of the antenna’s radiation: transmission loss (TL) and insertion phase delay (IPD) are caused when electromagnetic (EM) waves passing through the radome wall [1, 2], and phase distortions are incurred by IPDs, leading to boresight error (BSE) along with the asymmetric radome geometry. These may degrade the system performance of airborne radars, such as target detection probability and radar cross section (RCS) [1, 2]. Homogenous [3] and inhomogeneous [4] planar and tangent-ogive [5,6,7,8] and Von Karman [9,10,11]

Methods

Results

Conclusion