Ultrawideband Compact 50:200 Ohm Guanella Balun Using Asymmetric Broadside-Coupled Lines

We present the design and measurement of a planar ultrawideband 50:200 Ω Guanella balun operating with a 1 dB differential insertion loss from 0.35 to 3.4 GHz for ultrawideband radar antennas. We excite the Guanella balun with a Ricker wavelet centered around 700 MHz to 1.6 GHz and see little distortion in time domain. The response appears to be the best published low frequency response to date of a compact planar microwave Guanella balun. This Guanella balun importantly enables integrated compact feeding of high-impedance balanced antennas such as Resistivelv-Loaded Vee Dipoles.