M-CMA for digital signal processing adaptive antennas with microwave beamforming

This paper proposes a novel algorithm, called M-CMA (Modified Constant Modulus algorithm), which is unparalleled to give adaptability to microwave beamforming phased array antennas. Since microwave analog beamformers basically require much less RF devices than digital beamformer, the microwave analog beamformers based on M-CMA, that is adaptive microwave beamformers, can be cheaply fabricated. Therefore, they are much suitable for mobile communication systems where both miniaturization and low-cost are required for the equipment. Actually, M-CMA obtains the gradient vector by perturbing the microwave beamforming control voltage. Though M-CMA is implemented with a digital signal processor, M-CMA controls the microwave analog beamformer by utilizing the gradient vector. The microwave analog beamformer based on M-CMA is analyzed to have the following characteristics. (1) The beamformer can point its main beam to the desired direction in AWGN channels. (2) Although the beamformer has possibility to fail in ill solutions in CCI (Co-Channel Interference) channels, M-CMA can converge to the optimum solution when the desired direction is roughly a priori known