X-band substrate integrated waveguide (SIW) active antenna self-oscillating mixer (SOM)

This paper presents the design of an X-band active antenna self-oscillating down-converter mixer in substrate integrated waveguide technology (SIW). Electromagnetic analysis is used to design a SIW cavity backed patch antenna with resonance at 9.9 GHz used as the receiving antenna, and subsequently harmonic balance analysis combined with optimization techniques are used to synthesize a self-oscillating mixer with oscillating frequency of 6.525 GHz. The conversion gain is optimized for the mixing product involving the second harmonic of the oscillator and the RF input signal, generating an IF frequency of 3.15 GHz to have conversion gain in at least 600 MHz bandwidth around the IF frequency. The active antenna circuit finds application in compact receiver front-end modules as well as active self-oscillating mixer arrays.