This communication presents a differential dual-polarized filtering dielectric resonator antenna (DRA). In this antenna, a four-leafclover shaped dielectric resonator (DR) is excited with two groups of outof- phase modes. The novel configuration and differential feeding provide the DRA with high isolation for input ports, and the elaborately designed feeding strips ensure controllable input impedances for integration applications. After integrating with a pair of filtering baluns on the opposite side of the reflecting ground, the proposed DRA also exhibits good out-of-band rejection for each port with a wide stopband and two radiation nulls at band edges. A prototype has been designed and implemented, and reasonable agreement between the measured and simulated results can be observed.

In this letter, a differentially coplanar-fed filtering dielectric resonator antenna (DRA) is proposed for millimeter wave (mm-Wave) applications. To realize a low profile design, a novel coplanar feeding method is presented by incorporating a dielectric resonator and its feeding structure in the same layer which minimizes the assembly errors. The DRA is shaped by hollowing out the substrate and can be manufactured with a single-layer laminate using standard printed circuit board (PCB) technology. The DRA operates at TE111 mode which is excited differentially by a pair of microstrip lines with metallic vias. The filtering function is obtained by etching two pairs of slots with different lengths in the ground plane resulting in two radiation nulls at both upper and lower band edges. For demonstration, a prototype is designed, fabricated and measured. Good agreement can be observed between simulated and measured results.

A new decoupling method is proposed in this article, which simultaneously realizes port and radiation pattern decoupling, namely, high isolation and undistorted radiation patterns, respectively. The proposed decoupling method shows its effectiveness in $1\times 2$ dielectric resonator (DR) antennas (DRAs) even with zero spacing. Conformal strips are attached to the sidewall of the DRs and parallel to the E-plane of the DRAs. Coupled from the resonant DR, the conformal strips can generate an induced current, thus forming an induced field inside the DR. It can be noted that, inside the two DRs, the DR resonant field and the strip induced field are antiphase and in-phase, respectively. Tuning the conformal strips can change the amplitude ratio and phase difference between the resonant and induced fields, which can be used to cancel the fields inside the DR based on the superposition principle. When one DR is excited, the field inside the other DR can be very weak. The DRs can then work at their fundamental TE $_{\delta 11}$ modes independently. Therefore, their radiation patterns are not distorted together with high port isolation. A new indicator, energy storage proportion (ESP), is proposed to evaluate the decoupling effect. It can be found that, when the ESP gets close to 1, the radiation patterns will be restored together with high isolation. To verify the idea, $1\times 2$ DRAs are designed, fabricated, and measured. A reasonable agreement can be observed between the measured and simulated results for both H- and E-plane decoupled cases. All the measured overlapping impedance bandwidths are larger than 6%, the envelope correlation coefficients are lower than 0.059, and the isolations are higher than 20 dB. It should be highlighted that all the radiation patterns in this article have been restored, useful for practical applications using multiple-input multiple-output techniques.

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.

1×2 L-probe fed patch antennas are decoupled with undistorted radiation patterns in this paper, based on the TM01 and TM11 modes of the patch. Metallic vias are employed to increase the resonant frequency of the TM01 mode, whereas slots can be cut on the patch to decrease the frequency of the TM11 mode. When the E-fields of these two modes are with appropriate amplitude ratio and phase difference, the E-fields inside the excited patch will be superposed whereas those inside the coupled patch will be cancelled to a relatively low level. Further fine tuning the vias and slots can merge the resonant frequencies together and restore the maximum radiation along the boresight direction. To verify the effectiveness of the design idea, a prototype with zero edge-to-edge spacing is designed for 2.4-GHz WLAN applications. Good agreement can be observed between the measured and simulated results. The measured overlapping 10 dB impedance bandwidth is 5.7%, over which the isolation is larger than 20 dB. It should be highlighted that undistorted radiation patterns can be obtained with this approach.

In this letter, a differentially inserted-fed compact dual-band circularly polarized (CP) dielectric resonator antenna (DRA) is proposed. To realize a compact design, the inserted differential feeding structure composed of a pair of arc-shaped strips connecting with coaxial probes plays dual roles. It not only excites the fundamental mode HEM111 of the DRA, but also brings an additional resonant mode to form the second band. Besides, the lower and upper bands of the DRA are independently controlled by the DR and the strips, facilitating the design process of the dual-band DRA. For demonstration, a prototype is designed, fabricated and measured. Measured results show that the proposed DRA with the profile of 0.34 λ $_g$ achieves impedance bandwidth (|S $_dd$ 11|<-10 dB) of 30.4% and 18.5% and 3-dB axial ratio (AR) bandwidth of 8.06% and 6.38% with peak gain of 6.9 and 7.3 dBic for the lower and upper bands, respectively. Good agreement is observed between the simulated and measured results.