High-Gain Leaky-Wave Endfire Antenna Based on Hansen&x2013;Woodyard Condition

In this letter, a novel high-gain leaky-wave endfire antenna is proposed. By utilizing an air substrate parallel strip line, which is periodically disturbed by the radiating elements, such as the feedline, the phase constant of the antenna approaches the phase requirement of the Hansen & x2013;Woodyard (H & x2013;W) condition. By optimizing the size of the radiating element, which is dipole element, an approximately constant aperture distribution is obtained by the antenna. Thereby, with the characters similar to the H & x2013;W endfire antenna around the center frequency and moderate phase constant over the operating bandwidth, the antenna achieves a high gain, narrow beamwidth, and stable endfire radiation pattern. With the radiating aperture length of two wavelengths, the antenna generates the measured gain of 12.5 & x00A0;dBi at the center frequency of 5 & x00A0;GHz, operating bandwidth of 20.8 & x0025;, and measured 1 & x00A0;dB gain bandwidth of 16.2 & x0025;. Fabricated by metal, the antenna may be an attractive substitute for the long-distance communication applications, especially for the systems where cost and power capacity are important.