Local oscillator radiation from active integrated antennas

Active receiving antennas with integrated amplifier, mixer and local oscillators have significant radiation at the local oscillator frequency. Although this radiation may be out of band, it will be a problem in cluttered environments. In this paper the problem is evaluated through measurements and simulation on integrated microstrip patch antennas at 1.9 GHz. Radiation levels are compared for various substrate materials and configurations. It is concluded that, although reduction in local oscillator radiation can be made, the primary factor is the trade-off between manufacturing simplicity and performance.