A novel double-feed microstrip balun for planar antennas to improve radiating power

In order to improve the feed power of time-domain antenna, a novel symmetric three-layer double-feed balun is proposed, which can be excited by positive and negative pulses. The structure boasts compact size, good generality and easy integration with planar antennas. The method is to feed two transient pulses of opposite polarity into the two arms of antenna through the coupling conduction of common grounding and the microstrip line, so as to increase the electric field distribution on the surface of the antenna and increase the radiation field intensity. For validating the analysis, a double-feed microstrip balun whose feeding impedance is $50 \Omega$, developed with the basic model of antipodal Vivaldi antenna, is designed and simulated. It indicates that the radiating field of the antenna is increased by 1.39 times under the excitation of positive and negative pulses of the same magnitude with pulse width of about 1 ns.