One of the recent concepts in communication systems is Multiple Input Multiple Output (MIMO) that has the potential to improve channel capacity by utilizing multiple transmitters and receivers. However, to reduce the implication on the required radiating element footprint, multiple antennas should be replaced with a single antenna that provides orthogonal multiple radiation patterns associated with the feeding ports. In addition, the proper use of frequency spectrum is possible when different modes of an antenna can be excited at the same frequency with polarization and radiation pattern orthogonality.
This work proposes the idea of combining the multifunction device and multimode antenna with a dielectric resonator for a single band operation. The geometry of a cylindrical dielectric resonator has been perturbed to combine the radiating TM01δ and HEM11δ modes with the non-radiating mode TE01δ at the same frequency. The methodology of tuning several modes of DR with coupling mechanism and several practical concerns is mentioned in this work. The effect and rationalization of the introduced geometry perturbation parameters are presented. A prototype of the introduced concept is designed, fabricated and measured to prove the concept targeting the Wi-Fi MIMO applications. Afterwards, the designed device is used as a single element in a cascaded two element design where four different antennas work simultaneously at a single frequency with a filter. In summary, the main contributions of this work are: presenting the detailed procedure of geometry perturbation, including the metal placement on top of the resonator; proposing a coupling mechanism for tuning modes for simultaneous excitation; validating the introduced concept and methodology with a comparison between a simulated and measured prototype designed for MIMO applications; cascading two elements to obtain four independent antennas incorporating a filter.