Channel Cancellation Ratio in Highly Digital Direct RF Sampling Array Architectures

Abstract

Conventional receive digital beamforming (DBF) systems generally employ array architectures that use fixed radio frequency (RF) manifolds to combine the elements of several sub-apertures into a small number of digital channels. These channels are then used in adaptive beamforming to cancel interference. A significant limiting factor in the performance of an adaptive array is how well the transfer functions match among the various receiver chains. Emerging technologies have the potential to allow for much greater achievable channel match. These architectures typically use broad RF channelization filters followed by direct RF sampling. Most of the out-of-band and image rejection filtering is accomplished digitally, thus match among the various receiver channels is not limited by IF filtering. This paper characterizes this effect via analysis of simulated random realizations of the filters representative of channel transfer functions.