A Novel Low-Scattering Vivaldi Array Design Method by Loading Resistive Reflecting Units

In this paper, a novel low-scattering design method of Vivaldi array antennas is proposed in this paper, i.e., controlling structural mode scattering to cancel antenna mode scattering of the array. To achieve a more complete cancellation in a broad band, resistive reflecting units are elaborately co-designed with Vivaldi elements and loaded at critical positions of array edges. Thus, desired in-band co-polarized monostatic scattering cross section reduction (SCSR) is achieved. An 8 × 8 low-scattering Vivaldi array is calculated to verify the proposed low-scattering method, compared with a referenced array. Calculated results demonstrate the notable broadband SCSR, larger than 20dB compared to the metal ground in X-band, and broadband wide-angle scanning performances of the array are not affected by proposed low-scattering method.

I. Introduction

In radar and guidance systems, phased array antennas are preferred because of fast and flexible beam scanning ability which, is vital for target locating and tracking. In these systems, not only the broadband operation and wide-angle beam scanning performances are required, but also the low-scattering characteristic. Facing incident waves with different polarizations, scattering performances of phased array antennas vary a lot. When cross-polarized (cr-pol) waves illuminate, antennas exhibit as ordinary metals and dielectrics, therefore adding cr-pol absorbing structures can easily reduce the scattering without radiation and scanning performance deterioration [1]. However, when facing in-band co-polarized (co-pol) waves, low-scattering measures have to be co-designed with the antenna radiation and scanning properties, leading to design difficulties. Thus, studies on in-band copolarized low-scattering designs are of great research value, as well as the practical use.