A Theoretical Model for Frequency Response of a Cylindrical Resonator Antenna With the ${HE}_{11\delta }$ Mode Splitting Behavior

This paper presents a theoretical model of a cylindrical hybrid resonator antenna. The hybrid resonator consists of an annular ring ferrite and a cylindrical dielectric with a dc magnetic bias field, applied in direction parallel to the antenna height. The HE
_11δ
mode splitting behavior caused by tensor nature of the permeability of a biased ferrite is investigated. To validate the proposed approximate analysis, an experimental investigation of an antenna loaded with a biased ferrite is also presented. The presented theory is shown to demonstrate the measured results. The antenna is found to be used as frequency, bandwidth, and polarization tunable antenna. The operating frequency can be chosen in the range from 9.07 to 9.84 GHz. In addition, the bandwidth can be extended from 7.3% to 12.7%. The polarization can be switched from linear to circular. The features mentioned earlier can be achieved by applying the appropriate magnetic field due to the HE
_11δ
mode splitting behavior. The theoretical model, the design process, and the measured results are presented in detail. The antenna is also found to be capable of tuning the operating frequency as well as the frequency tuning range without changing the overall size of the resonator.