Wideband balun bandpass filter explored for a balanced dipole antenna with high selectivity

摘要: A novel microstrip wideband balun bandpass filter (BPF) is presented for development of a balanced dipole antenna with wide operating band and high frequency selectivity. By utilising the standing-wave property current distribution along half-wavelength (λ/2) open-ended line, out-of-phase signals are ideally obtained at two output ports balun. Meanwhile, proper coupling topologies between open-circuited λ/2 transmission line quadruple-mode resonators selected to achieve BPF both characteristics performance filtering properties. 1.65 GHz 32% fractional bandwidth first designed. The derived results not only exhibit good 0.49 dB amplitude imbalance 7.2° phase imbalance, but also selectivity relying on zeros. Next, this integrated flat shape towards high-selective radiation. Both simulated measured higher than 10 return loss 2.4 dBi radiation gain over 1.4–1.9 GHz.