A modified microstrip line for excitation of wide-band dielectric resonator antennas

A novel approach for effectively feeding a wide-band dielectric resonator antenna (DRA) of very low-permittivity is presented in this paper. It is shown that a tapered microstrip line with optimized length and width can provide excellent impedance matching. The impedance bandwidth of the antenna (S₁₁ <; -10 dB) associated with single resonance mode is over 35%. A minimum reflection coefficient of -60 dB is observed in the simulations for a dielectric resonator with dielectric constant of ε_r = 5. The broadside radiation pattern of the antenna is stable over the impedance bandwidth. Low cross polarization levels (<; -20 dB) across the frequency range 21-30 GHz are noticeable.