Shared Dipoles Inspired Horizontally Polarized Omnidirectional Antenna with Broad Bandwidth

A horizontal-polarized (HP) omnidirectional antenna with an extremely wide bandwidth and small gain variation is presented. To attain horizontally polarized omnidirectional performance and small size, eight shared dipoles, which are round-connected into an octagon-shaped array, are excited by a 1-to-8 power divider. To significantly improve the impedance matching and omnidirectional performance over a very broad operating frequency band, fragmented metal strips are introduced around the shared dipoles. In the proposed design, a desirable bandwidth of 92.3% (1.4–3.8 GHz) is obtained under a compact size of π × (0.32 λ
₀
)
²
× 0.01 λ
₀
, in which λ
₀
stands for the relevant wavelength at 1.40 GHz. Apart from that, the wideband antenna also attains excellent gain variation of smaller than 1.5 dB at the operating band.