Nonreciprocal and Magnetically Scanned Leaky-Wave Antenna Using Coupled CRLH Lines

Abstract

A new class of miniaturized nonreciprocal leaky-wave antenna (LWA) is proposed for wide angle scanning via magnetic tuning. A design is proposed based on coupled composite right left handed (CRLH) transmission lines (TLs) on a ferrite substrate for miniaturization with an external magnetic field control. Coupled TLs were previously utilized in a nonreciprocal LWA design with separate transmitter (TX) and receiver (RX) ports. In this work, CRLH TLs are employed to realize miniaturization, nonreciprocal properties and wide-angle scanning at the same time. To design the LWA, a circuit model was developed with the nonreciprocal propagation properties analytically calculated. For experimental validation, a 15-unit-cell prototype with a unit-cell length of only λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> /20 was manufactured and tested. The TX and RX beams were independently scanned in the E-plane up to 80° by changing the bias field ±50 Oe. The associated antenna gain varies between 3.5 and 5 dB at the operating frequency of 1.79 GHz as the beam is scanned. This is unlike traditional LWAs that achieve beamscanning via frequency control. Additionally, measured isolation between TX and RX ports was ~ 10 dB.