A Compact Wideband Slot-Loop Directional Antenna for Marine Communication Applications

A compact wideband high gain directional antenna is proposed in this paper for marine communications. The antenna consists of a back plane (reflector), a slot-loop antenna (driven element), and a director of rod. Based on the current distribution, the slot-loop antenna is equivalent to an array of three linear current dipoles. The dipole acts as an element of the director, which provides a high efficient director for slot-loop antenna according to theoretical analysis. Both the impedance bandwidth and the 1 dB gain bandwidth are 45% covering 1.7-2.7 GHz in this design. A gain of 11.2 to 12.2 dBi is obtained in the working band with only one set of directors. The directors have a dimension less than the antenna aperture in the H-plane, which can be seen as one director in the end-fire direction. Compared with the classic Yagi antenna with the same gain level, the newly proposed antenna is only half of the size in radiation direction, which is a breakthrough for the Yagi antenna design. This size reduction can significantly minimize the interference between ship-borne antennas. The antenna is fabricated using only metal of low cost, which is useful for the ship-to-shore/ship communicating applications and desirable for the large-scale deployment.