Wideband Planar Sleeve Dipole Antenna With Back Cavity

A novel, simple-structure, low-profile, wideband antenna with back cavity is proposed in this letter. The wideband antenna is derived from the planarization improvement of the sleeve dipole antenna. The antenna mainly consists of five parts, which are planar sleeve dipole, L-shaped feeding strip, substrate, coaxial feed, and back cavity. The planar sleeve dipole and the L-shaped strip are printed on both sides of the substrate plate. To verify the design, the antenna is processed and measured with the size of 0.5λ
_L
× 0.5λ
_L
× 0.16λ
_L
, where λ
_L
is the wavelength of the low frequency. From the measured results, the proposed antenna achieves a wide impedance bandwidth of 81.4% from 3 to 7.12 GHz with a return loss more than 10 dB. Moreover, the measured gain of the antenna is 6-9.5 dBi, and the radiation pattern is very stable over the entire frequency bandwidth.