Frequency agility is the ability of a waveform generator in
a radar to quickly switch its operating frequency from one fre-
quency to another. Such ability is very important for a radar
to account for atmospheric effects, jamming, mutual interfer-
ence with friendly sources, or to make it more difficult to lo-
cate through radio direction finding. Therefore, to generate a
phase-coded or frequency-chirped microwave waveform with
switchable carrier frequency is practically required.