Wideband Omnidirectional Dielectric Resonator Antenna Using Air and Dielectric Vias

A wideband omnidirectional dielectric resonator antenna (DRA) is investigated. It can be implemented using microwave substrates. A planar structure is used to excite the DRA modes <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{TM_{01\delta}}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{TM_{02\delta}}$</tex>. By using dielectric vias, the effective dielectric constant of the substrate can be increased, resulting in a compact size. Air vias are introduced to fine-tune the DRA modes. Thus, wideband response can be obtained by combining these two DRA modes and a patch mode. A wideband DRA prototype is designed, fabricated, and tested to verify the proposed concept. Good agreement is obtained between the measurement and simulation. Measured results show that the DRA has a 10-dB impedance bandwidth of 36.2%. It has a low profile of 0.1 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{\lambda_{0}}$</tex>, where <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{\lambda_{0}}$</tex> is the wavelength in air at the center frequency.