A Differential Voltage-Controlled Integrated Antenna Oscillator Based on Double-Sided Parallel-Strip Line

A voltage-controlled integrated antenna oscillator (VCIAO) integrating a differential voltage-controlled oscillator (VCO) with a double-sided parallel-strip line (DSPSL)-fed quasi-Yagi antenna based on the DSPSL is presented in this paper. The quasi-Yagi antenna is used not only as the radiating element, but also as the output power combiner and the resonating load of the differential VCO without any matching circuits or transition between them. The two sub-oscillators of the VCO on the opposite sides of the substrate share a common quarter-wavelength DSPSL resonator and a common inserted ground plane, which also works as the reflecting element for the quasi-Yagi antenna. The common DSPSL resonator terminated by a series varactor can not only help to synchronize the two sub-oscillators, but also realize tunable oscillating frequency. Due to the differential output of the proposed VCO, the cross polarization of the proposed VCIAO is suppressed to a great extent in the entire tunable frequency range.