A Compact Radome Mounted Monopulse Antenna for Direction-Finding Applications

This paper presents a compact monopulse antenna which can be fitted inside of a small diameter radome. The monopulse antenna is composed of four antenna elements and each antenna consists of a square open-ended waveguide(OEWG), a stepped impedance matching structure, and a conformal aperture. Because of the compactness and the conformal aperture of the element that can be mounted on the inner surface of the radome, the center space of the radome can be secured, which can provide a space for other sensors or devices. To verify the monopulse performance of the designed antenna, its sum (Sigma) and difference (Delta) patterns are calculated. The S pattern gains of the antenna are 15.3 dB, 15.1 dB, and 15.4 dB for f(l) GHz, f(c) GHz, and f(h) GHz, respectively. The normalized null depths of the. patterns are under -40 dB within the operational frequency.