Electronically Steerable and Fixed-Beam Frequency-Tunable Planar Traveling-Wave Antenna

The design of an electronically steerable wideband planar traveling-wave antenna is presented. The proposed antenna has a very simple structure based on a microstrip line loaded with several radiating elements and phase shifters between them. The phase shifters are based on tunable capacitances, in order to perform a continuous phase shift between the radiating elements and control the main beam direction. The radiating elements are complementary strip slots that have a very broad impedance bandwidth, thus allowing the antenna to have two different modes of operation: maintaining the main lobe direction over a significant bandwidth, 1.71-2.17 GHz, and performing a main beam scanning over this bandwidth with a maximum angle range of -45° to 45° at 2 GHz.