Design of Multiplate Back-Reflector for a Wideband Slot Antenna

A novel multiplate back-reflector wide-bandwidth unidirectional slot antenna is presented in this letter. The proposed structure not only maintains the wideband nature of slot structure, but also exhibits stable antenna gain and better front-to-back (F/B) ratio over the frequency band of interest. A slot antenna consisting of a pair of matching disc patches and a microstrip feeding line is employed to demonstrate the advantages of the new reflector structure. Four smaller metallic plates in different distances are used. Initial parameter measurement of the new slot antenna is conducted. The result shows an impedance bandwidth can exceed the original slot antenna bandwidth for $S_{11}\leq-10~$ dB in the range 1.56–3.14 GHz, stable gain more than 8.5 dB, and F/B ratio higher than 17 dB, with unidirectional radiation patterns and low cross polarization over the whole operating band. Those performances are exceeding the performance that a conventional back-reflector slot antenna can obtain.