Transmit Beampattern Synthesis for the FDA Radar

The frequency diverse array (FDA) radar has drawn great attention due to the periodicity of the beampattern in range, angle, and time. In this letter, we restudy the recent work that designed a time-invariant beampattern of the FDA radar, which can focus the transmit energy in a desired position. We reanalyze the derivation of the FDA beampattern synthesis and point out the neglected constraint condition, which leads the research of the FDA beampattern synthesis to an impractical direction. By comparing the replication of one of the prior works with our result, we draw a conclusion that it is impossible to obtain a beampattern merely focusing on some specific spatial positions and lasting for some specific time.