A 1-bit, Electronically Reconfigurable Reflectarray Antenna With an Octave Bandwidth

We present a wideband, low-cost, and electronically reconfigurable reflectarray antenna. The unit cell of the proposed design provides a 1-bit phase quantization with a bandwidth of 2.2:1 using only one PIN diode per unit cell. Each unit cell consists of a wideband dipole antenna placed above the common ground, and a reflecting circuit situated beneath the ground and electrically connected to the dipole antenna. By relating the impedances of the reflecting circuit in its two modes of operation and that of the antenna to the desired unit cell response, we derive the conditions needed to achieve very wide operational bandwidth over which the unit cell provides a 0°/180° reflection phase response. Using this approach, we designed, fabricated, and characterized a 625-element reflectarray prototype. The digital control circuit of the reflectarray was also designed, fabricated, and integrated with it. Both simulation and measurement results in E-, H-, and D-plane revealed that this reflectarray is capable of performing two-dimensional beam steering with a scan range of ±45° over a bandwidth exceeding one octave (4.5-9.2 GHz).