Broadband Long Rectangular Patch Antenna With High Gain and Vertical Polarization

A new microstrip rectangular patch antenna with high gain and vertically polarized radiation at endfires is proposed. The antenna has a wide bandwidth with a very low profile. Such antenna is based on a long microstrip line with periodic shorting-vias along the longitudinal direction. When both ends of the line are also shorted by vias, a resonant type of antenna is constructed. Two resonant modes with similar radiation patterns are generated. By optimizing the separation of the resonate frequencies of the two modes, a wide bandwidth is achieved. Measured results show that the antenna with a profile of 0.03 wavelengths in free space and a length of about 1.25 wavelengths can produce a bandwidth of 12.48% and a maximum gain of about 9 dBi.