Design of Novel Broadband Endfire Dipole Array Antennas

A novel broadband endfire dipole array antenna is presented in this letter. With a novel impedance matching method, this antenna is realized as a series-fed structure and four dipole elements on the same printed circuit board. The bandwidth of the antenna is increased by staggered tuning of the dipole elements. The measured results show that the antenna has an impedance bandwidth of 70.5% for voltage standing wave ratio ( $\mathrm{VSWR)} , a gain of 3.43–6.78 dBi and endfire radiation pattern. The total size is $0.595\times 0.977\; \lambda _o^2$ ( $\lambda _o$ is the free-space wavelength at the center frequency). The studies of the dipole length and distributed capacitor are also performed to verify the design theory. The advantages of broad bandwidth and unidirectional radiation pattern make this antenna favorable in wireless communication systems.