Low-Profile Frequency-Scanned Antenna Based on Substrate Integrated Waveguide

A beam scanning flat antenna array with the frequency that covers about the whole X/Ku-band is proposed in this paper. The radiation element is the continuous transverse stub (CTS) constituted by the substrate integrated waveguide (SIW). The CTS array is fed by a linear source which is a SIW parabolic reflector, and good impedance matching characteristics within a broad bandwidth are obtained. The beam steering direction is tunable with the frequency increasing within the operation band. The design principles of the SIW based CTS array and the feed structure are explained in details. One 16-element array is simulated, designed and fabricated. The measurement results show a scanning angle range from 52.2° to -16.8° with the 3-dB gain decreasing within the operation band from 8.5 GHz to 14.1GHz. At the center frequency of 12 GHz, it achieves a maximum gain of 18.1 dBi with an array size of 11.7?0×1.28?0, the first sidelobe level is -11.4 dB and the 3-dB beamwidth is 6.5°.