Small planar broadside radiation leaky wave antenna design

Abstract

The wireless communication systems in the last decade have an explosive growth. Antennas play an important part of the rapid growth of wireless communication systems. With this growth, great demands have come for antennas with low cost, low profile, light weight, easy fabrication, and suitability for mass production in order to support every aspect of communication systems. Microstrip antenna is one of the most popular choices for antenna design with above features. However, high radiation efficiency microstrip antenna is difficult to design due to its resonance phenomenon. Microstrip leaky wave antenna (LWA), therefore, becomes the good candidate to overcome this difficulty. The design and principle of operation of microstrip leaky wave antennas have been investigated thoroughly in past researches [1]-[4]. Traditional LWA proves the high radiation efficiency, however, occupies large area [3][4]. Another reason restricting the applications of LWA is that the normalized propagation constant of leaky mode is always greater than zero. This is the main reason that the LWA with broadside radiation pattern is very difficult to achieve. Some investigations focus on the concept of metamaterial, or so called composite right/left-handed transmission line (CRLH TL), to design the negative μande to make the normalized propagation constant equal to or smaller than zero. Therefore, leaky wave antenna with broadside radiation can be achieved [5]. However, this type of antenna for antenna designers needs more elaborated design procedures and requires a more accurate fabrication process. A novel planar broadside radiation leaky-mode microstrip antenna with small size and simple structure is proposed in this paper.