# A Study Of a Wide-Angle Scanning Phased Array Based On a High-Impedance Surface Ground Plane

## TL;DR

This paper introduces a wide-angle scanning phased array using a mushroom-like high-impedance surface ground plane, achieving up to 65° scan angle with excellent impedance matching through theoretical and numerical analysis.

## Contribution

It presents a novel antenna array design with a high-impedance surface ground that enables wide-angle scanning, supported by Floquet mode analysis and detailed mechanism explanation.

## Key findings

- Achieves up to 65° scanning angle in the E-plane.
- Excellent impedance match with small S11 across the scan range.
- The mechanism involves reflection phase control and surface wave excitation.

## Abstract

This paper presents a two-dimensional infinite dipole array system with a mushroom-like high-impedance surface (HIS) ground plane with wide-angle scanning capability in the E-plane. The unit cell of the proposed antenna array consists of a dipole antenna and a four-by-four HIS ground. The simulation results show that the proposed antenna array can achieve a wide scanning angle of up to 65$^{\circ}$ in the E-plane with an excellent impedance match and a small $S11$. Floquet mode analysis is utilized to analyze the active impedance and the reflection coefficient. Good agreement is obtained between the theoretical results and the simulations. Using numerical and theoretical analyses, we reveal the mechanism of such excellent wide scanning properties. For the range of small scanning angles, these excellent properties result mainly from the special reflection phase of the HIS ground, which can cause the mutual coupling between the elements of the real array to be compensated by the mutual coupling effect between the real array and the mirror array. For the range of large scanning angles, since the surface wave (SW) mode could be resonantly excited by a high-order Floquet mode $\textrm{TM}_{-1,0}$ from the array and since the SW mode could be converted into a leaky wave (LW) mode by the scattering of the array, the radiation field from the LW mode is nearly in phase with the direct radiating field from the array. Therefore, with help from the special reflection phase of the HIS and the designed LW mode of the HIS ground, the antenna array with an HIS ground can achieve wide-angle scanning performance.