Wideband MIMO dielectric resonator antenna with reduced RCS covering complete L-, S-, and C-bands (1–8 GHz) for next-generation wireless applications

The need for ultra-low latency and ultra-wideband in 6G applications requires efficient solutions for dielectric resonator antenna design. This paper presents the results of using a machine learning approach to improve the performance of a dielectric resonator antenna operating in the terahertz frequency band. The antenna design uses a polyimide substrate material with a compact size of 58 × 73 µm2. A silicon dielectric resonator in the shape of a rectangle ([Formula: see text] of 11.9) is placed on the patch to improve its performance. The antenna demonstrated a wide bandwidth of 4.3936 THz, a maximum gain of 6.02 dBi at 4.59 THz and an efficiency of 77.19%, exhibiting excellent radiation patterns and excellent correspondence. In addition, many machine learning methods were used to predict the bandwidth based on different antenna characteristics. Various measures were used to examine machine learning models, such as variance score, R2, mean square error (RMSE), mean absolute error (MAE) and mean square error (MSE). Out of the five models tested, the K-Nearest Neighbor (KNN) model had the lowest error values (MAE of 0.000808, MSE of 0.000002, and RMSE of 0.00135) and the best R2, reaching 0.9647 in bandwidth prediction. The suggested terahertz dielectric resonator antenna, confirmed by electromagnetic simulations and machine learning-based predictions, is a viable option for 6G terahertz applications due to its outstanding impedance and radiation matching performance.

Low-temperature Co-Fired Ceramics necessitate low sintering temperatures to enable cofiring with base metals, while dielectric resonator antennas demand temperature-stable dielectric properties; hexagonal perovskite Ba12Zn0.5Zr0.5Nb9O36 (R3̅m) ceramics exhibit excellent microwave dielectric performance but suffer from a high sintering temperature (1475 °C) and undesirably high temperature coefficient of resonant frequency (τf = 26.4 ppm/°C), limiting their practical applications. A synergistic strategy overcomes these critical bottlenecks by integrating BaWO4 (I41/a) for precise τf tuning and BaCu(B4O8) as a sintering aid to enable low-temperature sintering. XRD Rietveld refinement confirms the composites consist exclusively of impurity-free Ba12Zn0.5Zr0.5Nb9O36 and BaWO4 phases, and Raman spectroscopy validates the characteristic vibrational modes of NbO6 octahedra and [WO4]2- groups. The optimal composite at x = 0.89 exhibits exceptional all-around microwave dielectric properties (εr = 19.0, Q × f = 30100 GHz, τf = 3.0 ppm/°C) when sintered at 1000 °C, coupled with excellent chemical compatibility with Cu electrodes during cofiring. The DRA based on this composite delivers a broad 375 MHz bandwidth, 5.13 dBi gain, and 97.17% radiation efficiency at 9.14 GHz, highlighting its great potential for LTCC technology and microwave communication applications.

The paper proposes a wideband circularly polarized (CP) dielectric resonator antenna (DRA) array for X-band airborne SAR applications. The antenna element employs a dual-layer DRA excited by a T-shaped slot-coupled feeding. By placing a low-permittivity DRA beneath a high-permittivity one, both impedance and axial-ratio (AR) bandwidth are effectively improved. Then, a dual-feed sequentially rotated two-element subarray is developed, which provides the capability of forming a tilted main beam. In addition, grid-type metal walls are inserted to suppress mutual coupling and preserve polarization purity during beam tilting. To support broadband beam steering, wideband differential phase shifters are designed, while a Chebyshev power-distribution network is adopted to reduce sidelobes. A prototype was fabricated. Measurements demonstrate a 10-dB impedance bandwidth of 16.52% and a 3-dB AR bandwidth of 12.76% across 8.95–10.17 GHz. The array achieves a peak gain of 13.0 dBic, a tilted beam of 30°–35°, and sidelobe levels below −20 dB.

Based on the ternary phase diagram of BaO-CuO-SiO2, a series of BaCu2-xSi2O7-x (0 ≤ x ≤ 1) samples were prepared by using the conventional solid-state reaction method. By adjusting the Cu content, the phase composition between BaCu2Si2O7 and BaCuSi2O6 was effectively controlled. These two phases can coexist stably in the sintering temperature range of 1000-1060 °C. This two-phase coexistence state enhances the densification of ceramics. At x = 0.5 and sintered at 1020 °C, the sample exhibited optimal microwave dielectric properties, with a relative dielectric constant (εr) of approximately 8.07. Its Q × f (where Q is the quality factor and f is the resonant frequency) is as high as 47,200 GHz, and the resonant frequency temperature coefficient (τf) is -20.00 ppm/°C. When x = 0.5, adding 1 wt % BaCu(B2O5) (BCB) and 1 wt % LBSCA glass additives significantly reduce the sintering temperature to 890 °C. The samples still exhibit competitive microwave dielectric properties (εr ≈ 7.8, Q × f ≈ 19,900 GHz, τf ≈ -19.00 ppm/°C), along with excellent chemical compatibility with silver electrodes. These findings demonstrate that BaCu2-xSi2O7-x ceramics are promising candidates for low-temperature cofired ceramics technology (LTCC) applications.

This paper presents the systematic design, fabrication, and experimental validation of a compact quad-port dielectric resonator antenna (DRA)–based MIMO system for sub-6 GHz 5G applications. An aperture-fed excitation combined with optimized spatial arrangement is employed to achieve high inter-port isolation intrinsically, without using additional parasitic decoupling networks or external isolation elements. Each radiating element supports dual-mode operation by exciting a fundamental linearly polarized TE11δ mode at 3.5 GHz and a higher-order TE12δ mode at 3.9 GHz, enabling dual-band performance. The proposed four-port MIMO antenna achieves inter-port isolation exceeding 20 dB at the operating frequencies of 3.5 GHz and 3.9 GHz within a compact footprint of 0.35λ₀ × 0.35λ₀. Experimental results demonstrate excellent diversity characteristics with ECC below 0.05, CCL of approximately 0.1 bps/Hz, peak gain up to 2.62 dBi, and radiation efficiency approaching 89%. The moderate gain level is well suited for compact user terminals, indoor access points, and small-cell 5G devices, where omnidirectional coverage and low correlation are prioritized over high directional gain. The close agreement between simulated and measured results confirms the robustness of the design, making it a promising candidate for compact sub-6 GHz 5G communication devices.

This paper presents an efficient single-band rectenna for radio frequency energy harvesting at the 2.45 GHz ISM band. For this purpose, a stacked cylindrical dielectric resonator antenna (SCDRA) has been used. The RF harvester has also a matching network and a rectifier. Two different dielectric materials are used to broaden the bandwidth of the antenna and improve the gain at the frequency of 2.45 GHz. The SCDRA has been fed using aperture coupled feed technique. As well known, the antenna converts the electromagnetic waves into electrical signals, however these signals have a low RF power. To overcome this limit, a multi-stage voltage doubler rectifier is used. It allows increasing the efficiency and yields a satisfactory output voltage. Besides, a simple impedance matching network, is placed between the antenna and the rectifier circuit to ensure a maximum power transfer. We used the advanced design system (ADS) simulator for the design of the rectifier and matching network circuit. To investigate the performance of the proposed rectenna, simulation results are presented and discussed. Our rectenna achieves RF to DC conversion efficiency up to 70% with an output voltage of 3 V at an input power of 10 dBm.

ABSTRACT In this paper, a compact ultra-wideband (UWB) dual-port MIMO dielectric resonator antenna (DRA) with defected ground plane is proposed for on-body wireless body area network (WBAN) applications. The antenna employs a U-shaped dielectric resonator, two microstrip feeds, and parasitic strips to achieve wide impedance bandwidth and enhanced port isolation. Results reveal that wider and longer slots significantly improve impedance matching and inter-port isolation, while increasing slot depth in the dielectric enhances bandwidth and reduces coupling by suppressing surface currents. The fabricated prototype was experimentally validated on both rectangular and cylindrical tissue phantoms, as well as on animal tissue, demonstrating good agreement with simulations. The proposed antenna covers the UWB frequency range of 3.1–10.6 GHz with return loss below −10 dB and mutual coupling below −20 dB across the band. Furthermore, radiation analysis confirms broadside coverage with opposite phases for dual ports, ensuring reduced fading and improved channel capacity. The results confirm that the proposed antenna is robust for wearable and biomedical IoT devices requiring high data rates, low power consumption, and reliable UWB MIMO communication.

A very simple and novel structure of dielectric resonator antenna (DRA) to achieve high gain and excellent coupling is presented in this article. A low permittivity annular DRA made of glass achieves a very high gain of 13.23 dBi and excellent coupling. The DRA is fed by the rectangular waveguide which can be operated in X-band. The proposed structure is suitable for high power applications. The DRA resonates at 10.8 GHz and achieves 5.3 % impedance bandwidth. The proposed structure ensures a coupling efficiency greater than 98%.

A scalable and cost-effective phased array architecture based on dielectric resonator antenna (DRA) technology is presented for millimeter-wave applications. The proposed dome-on-cylinder DRA elements, encapsulated in a thermally conductive metal frame and excited through a suitable feeding network integrated into a multilayer PCB stack-up, enable two-dimensional wide-angle beam steering with minimized scan loss. A 64-element array prototype operating in the 24-GHz ISM radar band demonstrates 2D beam scanning up to ±70° in the E-plane and ±65° in the H-plane, with H-plane scan loss following an approximate cos<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.4</sup>(θ<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">_s</i>) dependence, significantly lower than the conventional cosine law. The same metal frame and high-thermal-conductivity DRA cores provide an efficient heat removal path, yielding at least an eightfold decrease in thermal resistance compared to an equivalent stacked microstrip patch array architecture, so that the aperture acts as a complementary heatsink. The electromagnetic and thermal performance of the array are validated through full-wave simulations and measurements of S-parameters, embedded-element and scanned-beam patterns, and steady-state temperature distributions, confirming the suitability of the proposed platform for high-power, wide-angle mm-wave communication and remote sensing systems.

Closing the Loop from Materials Design to mmWave Devices: Ultrahigh-Q, Thermally Stable Mg2SiO4 Ceramics Enabled by Synergistic Ionic Engineering for 24 GHz Dielectric Resonator Antennas

C-band dielectric resonator antenna with novel ultralow tanδ and temperature stabilized LaTmO3 microwave dielectric ceramics

Abstract This paper presents a novel dual-band cylindrical dielectric resonator antenna featuring a distinctive cross-ring structure that enables circular polarization (CP) across two critical frequency bands. The proposed antenna operates efficiently in both the 8–16 GHz microwave band and the 24–30 GHz millimeter-wave band, making it particularly suitable for ultra-wideband (UWB) and emerging 6G applications. Examination of the $S_{11}$ parameters reveals excellent impedance matching below $-10$ dB, yielding an impressive bandwidth of approximately 8 GHz (64.26%) in the lower band and approximately 6 GHz (23.72%) in the upper band. The antenna achieves stable CP through degenerate orthogonal modes, i.e., $\mathrm{TM}^{x}_{11\delta}$ and $\mathrm{TM}^{y}_{11\delta}$ , in the cylindrical dielectric resonator, with 3-dB axial-ratio bandwidth extending across both operating bands (approximately 8 GHz in the UWB band, representing 54.91% bandwidth, and approximately 6 GHz in the mmWave band, representing 20.12% bandwidth). The antenna delivers consistent gain performance, averaging 7.0 dBi in the UWB band and 6.5 dBic in the mmWave band. The novelty of this design lies in its elegant cross-ring feeding structure that simultaneously enables dual-band operation, excellent CP characteristics, and high radiation efficiency in a compact form factor. Simulation results closely align with measured data, confirming the antenna’s suitability for next-generation wireless communication systems.

Abstract The paper presents a compact triple-port equilateral triangular dielectric resonator antenna (ET-DRA) optimized for 5G N77 band applications (3.3–4.2 GHz). The antenna employs a shared radiator structure integrated with dielectric split ring resonators (DSRRs) to improve performance while maintaining a smaller footprint by localized H-field confinement. An ultra-wide impedance bandwidth is achieved due to the excitation of multiple modes in the ET-shaped DRA. Meanwhile, the integration of DSRR elements enhances the realized gain. The proposed antenna achieves a wide impedance bandwidth of 35% (3.2–4.44 GHz), an average gain of 5.7 dBi, and port isolation better than 15 dB across the operating band. The proposed design was fabricated and experimentally validated. Diversity parameters such as ECC, TARC, MEG, DG, and CCL were evaluated and found to be well within acceptable limits. This work presents an effective antenna that has a balance between compact size, wide bandwidth, and strong diversity performance, making it a promising solution for next-generation wireless communication devices.

This article presents a 3D-printed dielectric resonator antenna (DRA) array operating in the K-band, which incorporates a 3D-printed polarizing radome to achieve circular polarization. The antenna array consists of a 2 × 2 configuration of cylindrical DRAs, while the radome features a monolithic design with an internal polarizing layer made from an engineered anisotropic material. Both the antenna and the radome were fabricated using a low-cost 3D-printing process. The measurement results demonstrate that the antenna array with the radome achieves a maximum gain close to 12 dBic. The addition of the radome does not alter the radiation pattern or the maximum gain while successfully introducing right-handed circular polarization with a low axial ratio across the antenna’s 2.7% bandwidth.

Design and fabrication of a nano-composite epoxy resin-based dielectric resonator antenna using metasurfaces for X-band applications

A compact dual-port circularly polarized (CP) multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) for 28 GHz applications is presented. A single cross-shaped dielectric resonator is excited by two orthogonal microstrip feeds, supporting hybrid orthogonal modes that enable CP radiation at both ports without requiring perturbation cuts, parasitic elements, or decoupling structures. The fabricated prototype exhibits a measured 10 dB impedance bandwidth and 3 dB axial ratio bandwidth that fully cover the Federal Communications Commission (FCC)-allocated 28 GHz band (27.5–28.35 GHz). Port isolation remains better than 15 dB, and the antenna exhibits a peak gain of approximately 7.6 dBi with radiation efficiency exceeding 93%, within a compact 40 × 47 mm2 footprint. MIMO performance is verified through envelope correlation coefficient (ECC), diversity gain (DG), and total active reflection coefficient (TARC). The results demonstrate that the proposed single-resonator dual-port CP DRA provides an efficient and integration-friendly solution for compact mmWave MIMO applications in next-generation 5G/6G terminals.

In this paper, a MIMO antenna is presented consisting of 4 composite elements. Each antenna element consists of a U-shaped conducting structure and a perturbed barrel Dielectric Resonator Antenna (PB-DRA) structure. The former is loaded with a bow-tie patch, and it is parasitically excited through the U-shaped microstrip element. The additional bow-tie structure is designed for the gain enhancement in the 5G NR frequency range 1 (FR1) band and frequency range 2 (FR2). The PB-DRA has a dielectric constant of 8, and it is excited in higher-order mode to achieve resonance in FR2. The composite structure offers dual-band resonance with 3.85GHz resonant frequency in the FR1 band and 26.65GHz in the FR2 band, giving a large frequency ratio radiation characteristic. The proposed antenna offers impedance bandwidth of 2.02GHz in the FR1 band, and 5.3GHz in the FR2 band. Achieving multi-band resonance with a large frequency ratio is essential for exploiting the true benefit of 5G communication, as it enables operation across widely separated bands and supports multi-operator radio access networks (MORAN). The peak gains observed in the FR1 and FR2 bands are 8.23dB and 13.14dB, respectively. The proposed antenna is specifically designed to meet the requirements of the Open RAN compliant shareable 5G small cell radio unit specifications, by offering resonance in n77/n78 and n257/n261 bands, and end-fire radiation characteristics, ensuring sufficient coverage in the indoor and dense urban outdoor environment.

Wireless power transmission (WPT) is poised to revolutionize the future of wireless applications and sensing networks. High-gain antennas are essential for extending WPT coverage, but the unpredictable orientation of wireless devices remains a major challenge. To address this, this paper proposes a dielectric resonator antenna (DRA) with a new cone version (cupped-cone shape) to achieve high gain and a wideband circular polarization, ensuring consistent energy transfer regardless of device orientation. The proposed design enhances bandwidth by supporting multiple resonant modes. Combining two geometric shapes provides greater flexibility for fine-tuning and optimizing the DRA. The proposed DRA is excited using an innovative feeding mechanism with two elliptical slots and a modified microstrip feeding to produce wideband circular polarization, achieving large impedance and axial ratio bandwidths. The design is fabricated from polylactic acid using 3D printing technology, making it lightweight and cost-effective. Measurements show the antenna operates in the WPT band, covering the industrial, scientific, and medical (ISM) frequency of 5.8GHz with a 64% impedance bandwidth, 3-dB axial ratio bandwidth of approximately 31%, and a high gain of about 11.1 dBic by effectively utilizing a higher-order mode while maintaining the bandwidth.

This paper presents a novel dual-band cylindrical dielectric resonator antenna (DRA) integrated with concentric slot rings, designed for advanced wireless systems. The antenna operates over two distinct frequency ranges: 8–16 GHz (microwave) and 24–30 GHz (6G mmWave), offering wide impedance bandwidths of 8 GHz and 6 GHz, respectively, with reflection coefficients below −10 dB across both bands. The unique integration of the cylindrical DRA and concentric slot rings enables independent excitation of multiple resonant modes, ensuring stable E θ - and H ϕ -plane radiation characteristics and efficient mode separation. Simulation and measurement results show excellent agreement, with stable radiation patterns and peak gains of 5.5–6 dB in the microwave band and 7.5–8.5 dB in the mmWave band. The compact and easily integrable structure represents a significant improvement over conventional dual-band antennas, offering versatile multiband operation well-suited for high-capacity microwave links and emerging 6G mmWave communication applications.