High-Efficient Wideband Slot Transmitarray Antenna

A novel high-efficient, wideband, and single-linear-polarized slot-based transmitarray antenna is presented. The unit cell comprises three thin metallic layers with air gap in between, without use of any dielectric substrate. Each metallic layer has a square wide slot within which there are a number of parallel stubs. The wide slot has a high-pass response with notch at zero frequency. Addition of the stubs creates an extra controllable notch within the wide slot high-pass response. Due to the large spacing between the two notches, a passband with low-slope phase shift response is created which leads to a wideband transmitarray. The linear polarization behavior of the antenna along with a suitable feed horn and with no dielectric loss present has resulted in higher antenna efficiency. The design of a three metallic layer unit cell is also carried out through a simple circuit-based analysis approach. The transmitarray is fabricated and results are compared with those of simulation. The proposed transmitarray has a measured -1 dB-gain bandwidth of 15.5%, peak efficiency of 55%, and a cross-polarization level of better than -29 dB. The structure is simulated via HFSS software and ADS package is used for equivalent circuit (EC) simulation.