Software defined active microstrip patch antenna receiver

This paper presents a novel hybrid technique of receiving a sub-carrier multiplexed microwave signal with the help of an active microstrip patch antenna followed by a software defined I-Q phase locked loop (PLL). The proposed I-Q PLL uses a new type of software generated I-Q voltage controlled oscillator. Depending upon the signal type, the loop parameters can be easily changed through software for optimum demodulation, thus avoiding the necessity of changing loop parameters through hardware. Moreover, the phase detector of the PLL does not need the conventional filtering technique to remove the high frequency components.