Scan Blindness in Finite Microstrip Antenna Arrays

The work considers the problem of scan blindness in microstrip antenna arrays and shows the relationship between the results of analysis carried out with the assumption of infinite antenna array and the results for finite antenna array. The results for infinite arrays obtained using the concept of Floquet modes can be used jointly with empirical results for finite antenna arrays to obtain a method to optimize the parameters of dielectric substrate and the distance between radiating elements to get a scan sector with required scan loss.

I. Introduction

The characteristics of microstrip antenna arrays may be seriously deteriorated by surface wave excitation causing not only increase of power loss and coupling between antenna elements, but also scan blindness [1] when microstrip antenna array doesn't radiate at certain angles due to the interaction of surface wave with radiating Floquet mode under the assumption of infinite antenna array [2]. Blind scan angles appear on the scan element radiation pattern as nulls, these nulls may be even on the on-axes direction.