60-GHz electrically reconfigurable reflectarray using p-i-n diode

A 60-GHz band electrically reconfigurable reflectarray has been investigated. Each reflecting element is printed on a dielectric substrate and has a rectangular microstrip patch and a stub loaded with a single p-i-n diode. The reflection phase is changed by 180deg in accordance with the on/off state of the p-i-n diode; namely, the stub works as a single-bit phase shifter. A prototype consisting of 40 times 40 elements spaced at 0.7lambda was fabricated, and the reflection coefficients of the elements and the radiation patterns while the beam steering was performed were measured. Good agreement was observed between the results of the simulations and experiments.

I. Introduction

Reconfigurable reflectarray antennas have drawn much attention as alternatives for conventional phased arrays. A typical reconfigurable reflectarray antenna consists of an array of reflecting elements with phase shifters and a feed antenna to illuminate the array. The illuminated elements reradiate the incident field with phase shifts to obtain the desired phase front over the aperture. Because reflectarrays are spatially fed, the complex and high-loss power divider is not required, and therefore very little insertion loss is encountered at the feed. This feature is very attractive, especially for an array having a large number of elements at millimeter-wave frequencies.