A 1-D Electronic Beam-Scanning Monopulse Antenna Array Based on a Compact Stripline Phase-Shifter

A completely passive method of enabling 1-D beam-scanning for a monopulse antenna array with controllable sidelobe levels (SLLs) is presented in this letter. To achieve this unique function, a compact frequency-dependent phase-shifter composed of stripline resonators is proposed. This proposed phase-shifter provides similar sensitivity as conventional meander striplines, while its size is much smaller, enabling a successful implementation into a highly integrated feeding network with monopulse functions. The validation is provided by a 4 × 16 monopulse antenna array operated at X-band. A good correspondence is achieved between simulation and measurement for both S-parameter and far-field results. Measurement results of the prototype indicate a scanning range from -54° (10.5 GHz) to 48° (11.5 GHz) can be covered. Within the entire operational frequency range, the sidelobe levels are smaller than -15 dB for the sum channel, while a null depth better than -20 dB is observed in the difference channel. The proposed method is characterized by control simplification and very suitable to be deployed in cost-effective tracking systems.