Radiation Pattern Decoupled Dipole Antennas with Shorted Stubs for Millimeter-Wave Applications

A pair of shorted stubs are presented in this paper to decouple 1x2 millimeter-wave printed dipole antennas and to obtain restored radiation patterns. The 1x2 printed dipole antennas are placed side by side with a spacing of about a half wavelength. By inserting shorted stubs between the dipole arms and the ground, the induced current on the coupled antenna arm is shorted to the ground. Since there is little current left on the dipole arm of the coupled antenna, the isolation between the two ports can be enhanced and the radiation patterns can be therefore restored. To verify the idea, a prototype operating at 37-40 GHz frequency band was designed, fabricated, and tested. Good agreement can be observed. Measured results show an average isolation (-|S-21|) of 30 dB over the operating band, and the maximum radiation is corrected to the boresight direction simultaneously.