A low-profile DRA employing dielectric and air vias is investigated. The structure is realized utilizing PCB technology only. The dielectric vias are formed by filling up cylindrical holes with barium strontium titanate (BST) nanoparticles with a dielectric constant of 20 and a loss tangent of 0.023. Using this technique, the antenna can be made compact, without the need for using external, high dielectric-constant materials that are unavailable for standard PCB manufacturing. By skillfully arranging air vias inside the DRA, the resonant frequencies of different modes can be controlled, and a wide impedance bandwidth with stable radiation performance can be achieved. The whole antenna structure can be manufactured using standard PCB materials and manufacturing technologies. Our prototype achieves a wide measured impedance bandwidth of 47.5% and a maximum measured gain of 6.84 dBi. Furthermore, a small antenna footprint of $0.616\times 0.616\,\,\lambda _{0}^{2}$ with a low profile of $0.095~\lambda _{0}$ is achieved, where $\lambda _{0}$ is the wavelength in the air at the center frequency. A dual-polarized antenna is investigated using this design technique. It achieves an overlapping bandwidth of 34.88% of its two ports with isolation of higher than 25.76 dB and stable radiation performance across the passband.

Using dielectric vias, we propose a compact and wideband circularly polarized (CP) dielectric resonator antenna (DRA). The dielectric vias are realized by filling barium strontium titanate nanoparticles with a dielectric constant of 20 into a perforated printed circuit board (PCB) substrate. Owing to the high effectivedielectric constant of the dielectric via-loaded PCB substrate, the electrical size of the DRA is reduced. The arrangement of dielectric and air vias inside the DRA structure allows for redistributing the resonant frequencies of different radiating modes. This design incorporates a third higher-order mode into the passband, resulting in wide impedance and axial ratio (AR) bandwidths. A cross slot is used to excite the CP fields. The standard PCB process is utilized to manufacture the antenna structure. The fabricated prototype has measured impedance and AR bandwidths of 46.9% and 26.7%, respectively. The measured overlapping bandwidth is 25.4%. Our prototype has a compact footprint of 0.61 × 0.61 $\lambda^2_0$ where λ ₀ is the wavelength in free space at the center frequency. The proposed dielectric vias technique has potential abilities in size reduction and bandwidth enhancement.

For the first time, dielectric vias were used to design a substrate-integrated dielectric resonator antenna (SIDRA). The dielectric vias consist of cylindrical holes drilled into the PCB substrate and filled with presintered nanoparticles of barium strontium titanate (BST). The BST nanoparticles were found to have a dielectric constant of 20, with an approximate loss tangent of ~0.05. The dielectric-vias loaded substrate constitutes an effective medium for the DRA design. The dielectric vias are arranged in a concentric manner around a core substrate material region, giving a wideband multiring SIDRA. It was found that the wideband behavior is due to two different dielectric resonator modes, namely, the TE _δ11 mode and TE _δ31 half-mode. The TE _δ31 half-mode is a modified version of the TE _δ31 -mode of a regular dielectric resonator and is reported here for the first time. The measured and simulated -10-dB impedance bandwidths of the DRA are 33.4% and 35.8%, respectively.

In this publication, the use of a dielectric paste for dielectric resonator antenna (DRA) design is investigated. The dielectric paste can serve as an alternative approach of manufacturing a dielectric resonator antenna by subsequently filling a mold with the dielectric paste. The dielectric paste is obtained by mixing nanoparticle sized barium strontium titanate (BST) powder with a silicone rubber. The dielectric constant of the paste can be adjusted by varying the BST powder content with respect to the silicone rubber content. The tuning range of the dielectric constant of the paste was found to be from 3.67 to 18.45 with the loss tangent of the mixture being smaller than 0.044. To demonstrate the idea of the dielectric paste approach, a circularly polarized DRA with wide bandwidth, which is based on a fractal geometry, is designed. The antenna is realized by filling a 3D-printed mold with the dielectric paste material, and the prototype was found to have an axial ratio bandwidth of 16.7% with an impedance bandwidth of 21.6% with stable broadside radiation.

This paper investigates a new substrate-integrated (SI) filtering dielectric resonator antenna (DRA) using a multilayer microwave substrate, avoiding the need for a dielectric block. It deploys dielectric vias, air vias, and metallic vias, along with a square multi-mode substrate-integrated waveguide cavity to obtain a filtering response. By strategically designing the coupling slots and grounded metallic posts, two cavity TE₁₂₀ and TE₂₁₀ modes are merged with the DR TE^y_1δ1 mode to obtain a wide bandwidth. Measured results show that the single-band design has a 10-dB impedance bandwidth of 9.1%, a peak total antenna efficiency of 75%, and a peak realized gain of 5.7 dBi. Its out-of-band suppression level is greater than 18 dB. As compared with existing SIDRAs, our design has the highest stopband suppression level. This paper also investigates the first-ever dual-band filtering SIDRA. Its lower band is formed by the cavity TE₁₁₀ mode, DR TE^y_1δ1 mode, and a mode associated with a U-slot, while the upper band is created using two DRA-loaded cavity modes. A pair of shorted stubs is also introduced to enhance the roll-off in the lowest stopband. The dual-band design obtains measured impedance bandwidths of 11.3% and 6.1% for the lower and upper bands, respectively. They are suitable for wireless communication systems requiring a planar structure.