A Low-Profile, Low-Backlobe and Wideband Complementary Antenna for Wireless Application

Abstract

A new complementary antenna (or Huygens source) with a very low profile is presented. This antenna, composed of a pair of planar monopoles, a pair of bowtie shaped slots and a microstrip antenna, provides a broadband operation while its height is only $0.035 \lambda_{{{0}}}$ , where $\lambda _{{{0}}}$ is the wavelength referring to the center frequency of the operating band. More importantly, the proposed antenna radiates unidirectionally without the need of a metallic reflector. And therefore the total antenna volume is reduced to $0.011 \lambda _{{{0}}}^{{{3}}}$ . A prototype was fabricated and measured. It exhibits an impedance bandwidth $({\rm SWR} \leq 2)$ of 20.7% from 1.387 GHz to 1.696 GHz, a stable boresight gain of 6.11 dBi and a unidirectional radiation pattern with low back radiation ( ${ dB), low cross-polarization ( ${ dB).