On the Filtering Dielectric Resonator Transmitarray

This letter reports the first filtering dielectric resonator (DR) transmitarray that directs an incident wave in a designed direction. The DR elements are three-dimensional devices made of a dielectric material. The unit cell of the filtering transmitarray has symmetric lower and upper DR grids for receiving and transmitting energy, each having a cross slot on the metal plate to couple energy to each other. Each DR grid has 4 × 4 small rectangular DRs, supported by a hollow substrate. To flexibly design the radiation-beam direction, a full phase range of 0° to 360° is obtained by varying the DR size and, thus, its resonant frequency. At the lower filtering edge, At the lower filtering edge, the opposing electric fields are caused by the odd-mode coupling between the lower and upper cross-slots, giving one lower-edge transmission zero. For the upper filtering edge, the field cancellation is due to the DR grid resonating at a harmonic mode, providing the upper-edge transmission zero. The transmission passband is obtained by the coupling of a quasi-TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">111</sub> mode of each DR grid and a resonant cross-slot mode. For demonstration, a 26 GHz DR filtering transmitarray prototype consisting of 16 × 16 DR grids was designed, fabricated, and tested. It has a peak realized antenna gain of 19.07 dBi, a structure profile of 0.33<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub>, and a 3 dB gain bandwidth of 15.4% (23.9 GHz to 27.9 GHz). The bandwidth can cover the 5G mm-wave frequency band (24.75 GHz to 27.5 GHz)