Design of a planar microstrip antenna with wide bandwidth and omnidirectional radiation patterns using tightly coupled structures.

A wideband planar microstrip antenna with good horizontally polarized omnidirectional radiation performance is presented. Using tightly coupled structures, six planar dipole elements are deployed in a circular pattern, and radiation is synthesized into a horizontal omnidirectional radiation pattern by superposing the far‐field pattern of the six dipoles. Owing to the tight coupling between radiating elements, the proposed antenna has a wide operating band. The radiating elements are printed on a printed circuit board and excited by a balun with uniform magnitude and synchronized current. A prototype is manufactured and measured. The measurement results show that the impedance bandwidth of the proposed antenna is 102% $ \% $. The gain variation of the horizontal omnidirectional pattern is less than 1.2 dB in the 1.27–3.89 GHz band. Within the operating frequency band, the total efficiency and radiation efficiency are greater than 82% and 88%, respectively. The diameter of the antenna is 0.48λL ${\lambda }_{L}$, where λL ${\lambda }_{L}$ is the wavelength corresponding to the lowest frequency in the operating band. [ABSTRACT FROM AUTHOR]