Why do you use “smooth summing” of the RF signals?

Earlier simulated Doppler direction finders switched between adjacent antenna elements. Our RF summers combine the antenna inputs on a continuous basis. The method provides improved sensitivity because hard switching generates RF noise at the front end of the receiver, and it also produces sidebands which have the effect of causing adjacent channel signals to appear on the receiver’s frequency when the direction finder is operating. Our designs also provide a matched input impedance which allows the antenna to be located remote from the summer.