A Dual-Polarized Slotline-Coupler-based Antenna with Low-Profile and High Isolation

A microstrip dipole antenna with high isolation by using a cross-shaped slotline coupler is proposed in this paper. This dual-polarized antenna is composed of four dumbbell-shaped patches with corner cut, a cross-shaped slot coupler with stepped rectangular grooves, a pair of trapezoidal transmission line and a reflector. The proposed slot coupler is designed in a cross shape to form a differential signal at each end of the slot line. After being coupled to four dipoles, these differential signals will be radiated and combined, and then form dual polarization. The simulation results indicate that the microstrip dipole antenna not only achieves good impedance matching in the frequency range of 4.6 to 4.8 GHz, but also has a high port isolation below -20 dB in the whole working frequency band, with the average isolation of -26.12 dB and the highest isolation of -35.75 dB. More importantly, the proposed antenna has a rather low profile, only 2.3 mm.