Compact and Single-Fed Cavity-Cascaded Antenna Array With Horizontal Polarization Based on Microstrip Line

The concept of the radiative microstrip line antenna by breaking the symmetry of the fringing E-fields has been reported previously. Existing relevant studies are all with vertical polarization, namely the radiative fringing E-fields are orthogonal with the microstrip line. In this communication, by bending the transmission lines every half wavelength and loading blocking stubs on the same side, the L-shaped cavity-cascaded antenna array that produces horizontal fringing E-fields using a single feed can be obtained. The proposed antenna has the scalable ability along one direction to control the peak gain within a certain degree. A 12-segment cavity-cascaded antenna array with the size of $3.5 \times 0.8\lambda ^{\mathbf {2}}$ at the center operating frequency is fabricated. The measured −10-dB impedance bandwidth covers 5.12–5.35 GHz and the peak gain reaches 12.4 dBi. The proposed antenna exhibits a high aperture efficiency of 58.1%, so it is a compact and easy-to-feed antenna structure to obtain a high aperture efficiency.