Microstrip-Fed Surface-Wave Antenna for Endfire Radiation

This communication presents a microstrip-fed surface-wave antenna for endfire radiation. The antenna has the advantages of high endfire gain, wide endfire gain bandwidth, and stable endfire radiation pattern. It consists of a microstrip line with air media and a dielectric cuboid. The half-mode dielectric waveguide, which is made up by the dielectric cuboid and the air substrate introduced by the microstrip line, is the radiating structure of the antenna. Fed by a microstrip line, the half-mode dielectric waveguide couples the energy continuously with a moderate phase constant, which is helpful for the antenna to realize a high endfire gain and a stable endfire radiation pattern. With a low dielectric constant, the half-mode dielectric waveguide has a stable radiation performance within a wide bandwidth. With a length of 5.76 wavelength, the antenna achieves a maximum endfire gain of 13.3 dBi at 4.75 GHz. The 1 and 3 dB gain bandwidths of the antenna is 18.1% and 37.8%, respectively. Good matching is obtained from 3 to 6.5 GHz.