Title :
A Low-Profile Wideband Planar Antenna
Author :
Mingjian Li ; Kwai-Man Luk
Author_Institution :
State Key Lab. of Millimeter Waves, City Univ. of Hong Kong, Hong Kong, China
Abstract :
A wideband planar antenna with a low profile of 0.095λ0, where λ0 is the wavelength referring to the center frequency of the operating band, is proposed. Using the concept of complementary antenna, two shorted quarter-wave microstrip patch antennas, operating as magnetic dipoles, and two planar electric dipoles are connected together and excited simultaneously by a coaxial-to-microstrip impedance transformer. For further size reduction and back radiation suppression, a U-shaped reflector is employed. Experimentally, the proposed antenna exhibited an impedance bandwidth of 51.5% with SWR ≤ 1.5 from 1.96 to 3.32 GHz, a boresight gain of 6.9 ± 1.1 dBi and a unidirectional radiation pattern with low cross-polarization and back radiation levels. Moreover, the dc grounded structure fulfills the requirement for lightning protection in outdoor applications.
Keywords :
antenna radiation patterns; broadband antennas; dipole antennas; microstrip antennas; planar antennas; transformers; SWR; back radiation levels; back radiation suppression; center frequency; coaxial-to-microstrip impedance transformer; complementary antenna; dc grounded structure; frequency 1.96 GHz to 3.32 GHz; impedance bandwidth; lightning protection; low cross-polarization; low-profile wideband planar antenna; magnetic dipoles; operating band; outdoor applications; planar electric dipoles; size reduction; two shorted quarter-wave microstrip patch antennas; unidirectional radiation pattern; Low-profile antenna; unidirectional patterns; wideband antenna;
Journal_Title :
Antennas and Propagation, IEEE Transactions on
DOI :
10.1109/TAP.2013.2267715