Direct design of focusing filters for wideband direction finding

A time-domain formulation of the wideband direction-finding problem is presented from a multichannel filtering perspective. The filter is designed to achieve focusing as in the coherent signal-subspace processing wherein the signal subspaces are effectively integrated (focused) over the signal bandwidth. Specifically, a one-step filter coefficient evaluation technique termed direct design that avoids explicit evaluation of the frequency response is proposed. Aspects concerning effective and expeditious design are emphasized and insights are provided to accomplish focusing over spatial sectors. Simulation studies indicate the competing performance of the direct design with the two-step technique