Beamwidth tuning in a composite right/left-handed (CRLN) leaky-wave antenna using non-uniformly biased varactors

A novel and efficient approach to electronically control the beamwidth of radiation patterns is presented for the first time in a leaky-wave antenna. The proposed antenna can continuously vary the beam direction and beamwidth by adjusting the bias voltages of varactor diodes distributed along a single antenna at a fixed frequency. Maximum directivity is obtained when the varactors are uniformly biased, and the radiation angle is scanned by varying this bias voltage. By introducing non-uniform bias distribution, the beamwidth can be broadened. This concept is experimentally demonstrated at 2.95 GHz. A 66% beamwidth variation is achieved.