Optimized Annular Leaky Wave Antenna Architectures for Vehicular Communication

In this article, a low-profile, compact (1.36 λ0 × 1.24 λ0 × 0.04 λ0), microstrip, annular leaky wave antenna, with beam scanning capacity, (−44° to +45°) has been proposed in the frequency band of 5.5–6.5 GHz. The leaky wave structure consists of four annular microstrip rings arranged in a circular manner. The 2D cylindrical leaky wave propagates outward radially from the source along the interfaces of this structure. The periodic repetition of the rings in a circular pattern results in a compact structure compared to the linear repetition in leaky wave structures, adding to the novelty of the design. The dimensions of the ring are so chosen as to excite the dominant TM mode of the structure and thereby generate directive radiation patterns with beam scanning property. The operating frequency band covers the sub-6 GHz band, which is suitable for automated vehicular communications. Most of the antenna designs earlier reported for vehicle-to-vehicle communications produced omnidirectional patterns. On the contrary to this, the structure presented in this work, prevents unnecessary dissemination of signals by producing a directional pattern that gives wider angular coverage through beam scanning. A symmetric beam scan is obtained in the frequency band of interest, with a measured gain of 1.2 dB and a gain variation between 0.6 dB and 2.62 dB.