Diversity antenna using dipole/monopole modes with simple configuration

This paper introduces an integrated diversity antenna that uses dipole and monopole modes, and that has a simple configuration and a high isolation property. In dipole mode, mainly the horizontally disposed dipole element radiates. In monopole mode, mainly the vertically disposed GND of the microstrip line for feeding the dipole radiates. In the proposed design, the microstrip line is constructed across the gap with a feed point for monopole mode. However, the coupling between the microstrip line and the feed point is low, and the signal can pass to the dipole. This is because the dipole element that is located close to the GND acts as an open stub with an approximately 1/4 wavelength. The advantage of this design is that no extra space is needed for a slit on the GND to integrate two modes using one element. We have shown that the mutual coupling between the two modes is low: |S₂₁| is approximately -15 dB at the center frequency. In addition, the correlation coefficient is small according to calculations and measurements.