Broadside Scanning Fixed Frequency LWA With Simultaneous Electronic Control of Beam Angle and Beamwidth

TLDR: In this paper, a periodic leaky wave antenna (LWA) is presented for fixed frequency beam scanning in microstrip line technology, where both the beam angle and the beamwidth can be controlled electronically.

Abstract: In this article, a periodic leaky wave antenna (LWA) is presented for fixed frequency beam scanning in microstrip line technology. Both the beam angle and the beamwidth can be controlled electronically. The unit cell of the antenna is loaded with shunt stubs, which are either short or open-circuited, using p-i-n diodes as a switch. The switching of the stub alters the impedance loading of the antenna, leading to a change in the propagation constant and thus the main beam angle. The input impedance of the stubs is chosen for symmetrical beam scanning through the broadside direction. A total of 50 distinct main beam positions with an angular separation of approximately 1° are selected from the different switching states using an iterative process. The second set of p-i-n diodes are inserted between the consecutive unit cells to control the leakage and, hence, the beamwidth. The antenna is fabricated and measured at 2.45 GHz. The measured main beam angle scans from −26° in the backward direction to +24° in the forward direction, through broadside, with an overall measured gain variation of 1.2 dB. Also, the beamwidth can be continuously tuned up to a maximum of 204%, keeping the gain variation within 1.2 dB.