An SIW-Fed Cross-Dipole Antenna With Broadband Circular Polarization for MMW Applications

In this communication, a broadband substrate integrated waveguide (SIW)-fed circularly polarized (CP) cross-dipole antenna is proposed for millimeter-wave (MMW) applications. Its radiation parts consist of a cross dipole and reflecting ground, which are etched on two substrates. The antenna is fed by an SIW through a double-sided parallel-strip line (DSPSL). In addition, zigzag edges and L-shaped etches are utilized to expand the impedance bandwidth (IBW) and axial-ratio bandwidth (ARBW), respectively. By these methodologies, the antenna prototype possesses a measured IBW of 34.6% from 22.5 to 31.9 GHz, an ARBW of 23.1% from 24 to 30.25 GHz, and a peak gain of 8.8 dBic at 29.5 GHz. In comparison to general coaxial-line-fed cross-dipole antennas with a nonplanar topology and high profile of
$0.25\lambda _{0}$
(
$\lambda _{0}$
is the free-space wavelength at the center frequency), the proposed antenna with PCB process maintains broadband and owns a low profile of
$0.16\lambda _{0}$
, which makes it more desirable for MMW integrated circuits.