Dielectric Resonator Antenna Array Research Articles

A Compact Phase-Controlled Pattern-Reconfigurable Dielectric Resonator Antenna for Passive Wide-Angle Beam Scanning

The function of passive wide-angle beam scanning is desired by the base station antenna to provide “green” cellular services. In this communication, such function is realized by designing a compact phase-controlled pattern-reconfigurable dielectric resonator antenna (DRA). The proposed DRA has a compact structure with a side length of 0.38 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> and excites the fundamental TE and TM modes by diverse ports. By assigning phase between diverse ports, E-plane tilted patterns are synthesized with ±66° scan angles. Its pattern-reconfigurable capability makes contributions for increasing array beam scanning angle and minimizing gain fluctuation. A passive four-element array is verified to have an enhanced beam scanning angle of ±81° with a gain fluctuation of 1.25 dB. The maximum gain of the scanning beam is located on the off-axis angle of ±66° and achieves a wide 3 dB scan coverage of ±105°. Good agreements have been shown between the measured and simulated results. The proposed phase-controlled pattern reconfigurable DRA and DRA arrays have an impedance bandwidth of 3.33% (2.95-3.05 GHz) for a sub-6 GHz wireless system. They enable the wide-angle beam scanning for base station antenna and provide a cost-effective passive system for “green” communications.

Frame Integrated Wideband Dual-Polarized Arrays for Mm-Wave/Sub 6-GHz Mobile Handsets and Its User Effects

In this work, wideband dual-polarized dielectric resonator antenna (DRA) arrays are designed for 5G mobile handsets and integrated with the sub-6GHz antenna. The dielectric resonators, surrounded by concentric air holes and metal vias, are excited by two orthogonal slots and fed through microstrip lines, providing a wide bandwidth from 25.3 GHz to 29.8 GHz. A high isolation of above 40 dB is obtained between the ports of the orthogonally polarized antennas. Based on the dual-polarized DRA, two 1 × 4 arrays are built and integrated with the longer metal frames of the handset, without occupying extra space on the chassis. The scanning angle for the proposed array is from 47° to 121° for the gain of above 10 dBi, and the overall handset antennas provide a large coverage efficiency of 80% for a threshold gain of 5 dBi. User effect has also been investigated, manifesting that the horizontally polarized antennas are less influenced by the hands in both the one-hand and the two-hand data modes. Furthermore, a sub-6GHz antenna is designed with a wide operating band from 0.7 GHz to 0.94 GHz simply by making use of the shorter frames and the dual-layered DRAs, with a small ground clearance of 2 mm remained. The performances of the arrays are validated by measuring the representative antennas. The proposed antenna is a good candidate for future handsets due to its high integration with the metal frames and with the LTE antenna, its large bandwidth and large coverage in free space and different user scenarios.

Wideband circularly polarized aperture coupled DRA array with sequential-phase feed at X-band

A novel 2 × 2 wideband dielectric resonator antenna (DRA) array with circular polarization and fed with a sequential-phase feeding network at the X-band is presented in this paper. The proposed DRA array is fed by an aperture coupled feeding network. Each DRA element is constructed by joining two identical pieces of half-cylindrical shape; those are shifted with respect to each other to produce two orthogonal modes, in order to achieve a broadband circular polarization and wideband impedance matching simultaneously. The rigorous analysis and optimization processes throughout this paper are carried out numerically. The proposed array demonstrates a maximum realized gain of 10.3 dB. The measured matching bandwidth ranges from 8 to 12 GHz (40%), with about 37% 3-dB axial ratio bandwidth within the matching bandwidth. The quadruple DRA elements array is fabricated, and its scattering parameters and far-fields performance are measured to validate the numerical results. Acceptable agreement between the simulated and measured results is accomplished. It is demonstrated that the proposed antenna is a potential candidate for radar and satellite applications at X-band.

Advanced design of higher mode‐based dielectric resonator antenna array featuring high‐gain operation over a large frequency band

AbstractA higher mode‐based dielectric resonator antenna (DRA) featuring attractive characteristics has been explored and successfully demonstrated for use in wireless industry. In here, an improvised elevated feed platform has been conceived to exploit HEM12δ mode in a cylindrical DRA. An additional filtering mechanism by a selective loading has been introduced to achieve a clean and exclusive HEM12δ resonance. A single unit has been characterized at C‐band based on the available characterization facility and experimentally verified ensuring 22% wide matching bandwidth with as much as 11 dBi peak gain. A practical 2 × 2 array with a corporate feed has been successfully demonstrated. A consistent radiation pattern over about 10% matching bandwidth has been experimentally demonstrated. This ensures a flat peak gain (13‐14 dBi) over the full usable frequency band. This is novel in terms of its pure higher mode operation supporting a wireless system with uniform gain characteristics. Its improved features compared to the earlier designs have been clearly discussed.

Conformal Subgridding and Application to One-Eighth Spherical Shell Dielectric Resonator Antenna Array

To model the object with concave and convex surfaces accurately, an economical conformal subgridding scheme is proposed in this article. Its double conforming procedure with coarse grid (CG) and fine grid (FG) guarantees the modeling accuracy. Fast linear interpolation effectively exchanges electromagnetic fields information on the interface between grids of two sizes. One-step leapfrog alternating direction implicit (ADI) finite-difference time-domain (FDTD) method overcomes the Courant stability condition in FG region; meanwhile, conventional FDTD ensures the efficiency of simulation in CG region. While we concern the unconditionally stable method, there is not any grid omitted in our irregularly profiled fine region and any extra time wasted in solving small-scale tridiagonal matrixes cell by cell. To verify our codes, a 2-D arc component has been simulated first. Then the performance of a probe-fed normal one-eighth spherical dielectric resonator antenna (DRA), a new designed conformal-microstrip-fed one-eighth spherical shell DRA, and a four-element array with the spherical shell DRAs connected by a T-shaped power divider has been calculated by our codes. Satisfactory performance of the antenna has been obtained in return loss and radiation patterns, which are verified by measured results. The shell antenna features smaller size, lighter weight, and more convenience in conforming to the corners of the instrument housing, even with different dimensions. Most particularly, the proposed conformal subgridding scheme and its hybrid FDTD implementation perform outstandingly in simulating the thin shell antenna in terms of computer memory, CPU time, as well as accuracy.

An X-band gain-enhanced bidirectional antenna array using strip-loaded dielectric resonator operating in TE3δ1 mode

AbstractA bidirectional dielectric resonator (DR) antenna array using back-to-back quasi-Yagi antenna configuration is proposed and implemented for the first time. The DR operating at higher-order TE3δ1 mode is used as a magnetic dipole, applying for the driver of quasi-Yagi antenna. Due to the high-order mode employment, the antenna gain can be enhanced. By partially loading the metallic strip on the side wall of the DR, the gain can be further enhanced. In addition, a simple dual Marchand balun is constructed for feeding the two quasi-Yagi antennas directly for bidirectional radiation. To verify the design concept, a prototype operating at the X-band is fabricated and measured. Good agreement between the simulated and measured results can be observed.

On the fabrication of thin-film artificial metal grid resonator antenna arrays using deep x-ray Lithography

In this paper, a unique microfabrication approach for designing high permittivity, high gain and wideband thin-film artificial metal grid dielectric resonator antenna (GDRA) arrays for mm-wave applications is presented. Fabrication of the GDRAs with a strip template frame is based on deep-x-ray lithography (DXRL) using a 500 µm thick polymethylmethacrylate (PMMA) layer as the photoresist. The simple low-cost fabricated DXRL mask for exposure consisted of gold absorbers patterned by direct-write ultraviolet (UV) laser lithography on a carbon substrate. To avoid the trapping of gas bubbles in the dense, high aspect ratio (HAR) deep grid structures, a novel development approach was introduced utilizing in-vacuum, room temperature dip development to facilitate the collapse of forming gas bubbles. The developed voids were subsequently electroplated to a nickel thickness of 300 µm to obtain high permittivity artificial dielectrics. The paper describes the entire fabrication sequence. Also, the x-ray mask and DXRL structures are examined for dimensional accuracy and structural quality. This strip template frame approach has superior performance in terms of impedance bandwidth, gain and radiation efficiency as compared to the previously published solid template frame approach. For the purpose of the demonstration, a four-element GDRA array sample was fabricated and tested. A wide measured impedance bandwidth of 5 GHz from 58 GHz to 63 GHz and measured broadside radiation pattern with a peak gain of 10.9 dBi was achieved.

Millimeter-Wave Rectangular Dielectric Resonator Antenna Array With Enlarged DRA Dimensions, Wideband Capability, and High-Gain Performance

In this communication, a rectangular dielectric resonator antenna (DRA) is integrated with a backed cavity to enlarge the DRA side length by 1.8 times. The backed cavity also reduces the sensitivity of the DRA resonance to the DRA size, resulting in a relaxed fabrication tolerance. Based on the enlarged DRA design, a stacked DRA (sDRA) is proposed to improve the bandwidth from 8.7% to 15% and enhance the realized gain by an average of 1.5 dB. The proposed mechanisms are verified by fabricating a $4\times4$ sDRA array with an enlarged DRA side length of 1.8 mm ( $0.40 {\lambda }$ ), an improved bandwidth of 62.7–73.9 GHz (16.4%), and an enhanced measured gain of up to 17.2 dBi. The enlarged DRA dimension permits a higher DRA operating frequency without reducing the DRA size. The proposed millimeter-wave (mmW) sDRA array provides a wide bandwidth and high-gain solution for 67 GHz unlicensed band communications.

1×4 Dielectric Resonator Antenna Array with Corporate Feed for C-Band RADAR

A four element 1×4 dielectric resonator antenna array with corporate feed structure has been designed and investigated in this paper. microstrip feed has been used to power the corporate feed structure. Proposed antenna radiates at the C-band frequency of 6.5GHz which is widely used for the RADAR applications. For the design of corporate feed equal split Wilkinson power divider concept is been used. Arlon material has been used as base to the antenna which is having a thickness of 0.79mm. Proposed antenna is having a gain of 12dB. From the return loss and smith chart plots we can observed the impedance matching characteristics of the antenna array. A beam width of 250 is obtained with a SLL of 15dB which is best acceptable for array applications.

A steerable dielectric resonator antenna array with isoflux radiation pattern

AbstractA dielectric resonator antenna array is presented which is intended for use as an integrated solar panel antenna on low Earth orbit small satellites, such as CubeSats. This array has a back‐to‐back Yagi‐Uda topology and can steer its beam ensuring a constant flux density at a satellite ground station. This isoflux gain profile is formed by the envelope of the steered beams which are controlled using a single digital phase shifter. The array achieved a beam steering limit of ±66° with a measured maximum gain of 11.4 dBi.

Optimum Design of a Beam-Forming Array of S-Shaped DRA Elements With a Superstrate on an SIW Feed for 5G Mobile Systems

In this letter, an array of dielectric resonator antennas (DRAs) is proposed for the fifth-generation mobile network. A novel S-shaped DRA is presented as array elements. The proposed configuration is achieved by making two symmetrical segments on a conventional rectangular DRA. The results show that in this configuration the higher order modes of antenna are excited, and therefore, the 3 dB gain bandwidth and impedance bandwidth of antenna are increased. The volume of the proposed DRA without ground plane is 0.38 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The proposed DRA provides maximum bandwidth and gain per unit volume compared to similar designs in the literature. Furthermore, the benefit of a mutual coupling (MC) compensation approach in a linear DRA array is investigated. The results show that the accuracy of a computed MC matrix is better at the resonance frequency relative to other frequencies. Also, the performance of a beam-forming algorithm is improved by using this matrix for compensating the MC effects. The proposed array is fabricated and its characteristics are measured. A very good agreement between the numerical and measured results is obtained.

Mutual coupling reduction in circularly polarized dielectric resonator MIMO antenna

In this article a novel circularly polarized (CP) rectangular dielectric resonator antennas (RDRA’s) array has been designed. A unique conformal feeding strip has been used to excite the RDRA’s having a distance of λ/2. Various techniques are investigated to reduce mutual coupling (MC). Different formations, comprise of reorientation of the antennas have been employed to suppress MC and to enhance CP bandwidth. By the unique orientation the mutual coupling has been reduced by ~ 14 dB. A broadband circular polarization over a bandwidth of ~ 18.8% in conjunction with an impedance matching bandwidth of ~ 11.3 % has been achieved. The design has been modeled and simulated using computer simulation technology (CST). Two different simulation techniques i.e. finite integration technique (FIT) and Finite element method (FEM) have been used to compute and validate the results respectively. A significant resemblance in results have been observed.

Low-Profile Artificial Grid Dielectric Resonator Antenna Arrays for mm-Wave Applications

Wideband artificial grid dielectric resonator antenna (GDRA) arrays at 32 GHz for mm-wave applications are presented. The antenna array comprised a GDRA layer and a substrate-integrated waveguide feeding layer. The GDRA array layer is built by embedding small rectangular metal grid structures in low-permittivity dielectric polymethyl methacrylate (PMMA) using deep X-ray lithography (DXRL) and electroforming. The rectangular metallic inclusions significantly increase the effective permittivity of the base material up to 17 by creating high electric flux density regions inside. Low-loss substrate-integrated waveguide (SIW) feeding with longitudinal slots is utilized to excite the GDRA array layer. A $200~\mu \text{m}$ -thin perforated layer of PMMA is applied between the rectangular grid structures and the SIW feedlines to avoid shorting the metal inclusions to the excitation slots while improving broadband energy coupling to the GDRA layer. The size of the single GDRA array element is only 2.7 mm $\times2.7$ mm $\times0.5$ mm ( $0.29\lambda _{\mathrm {o}}\times 0.29\lambda _{\mathrm {o}}\times 0.05\lambda _{\mathrm {o}}$ ). Four-element ( $1 \times 4$ ) and eight-element ( $1 \times 8$ ) GDRA arrays have been fabricated and measured. A measured impedance bandwidth of 6 GHz with a broadside peak gain of 12 dBi and 76% measured radiation efficiency is obtained at 32 GHz for the $1 \times 8$ GDRA array.

60 GHz Substrate Integrated Waveguide-Fed Monolithic Grid Dielectric Resonator Antenna Arrays

Artificial grid dielectric resonator antenna (GDRA) arrays integrated with longitudinal slot-fed substrate integrated waveguide networks are demonstrated at V-band for wideband and high-gain applications. The effective permittivity of a 500 μm thick, low-permittivity polymethyl methacrylate substrate is locally increased by a factor of 22.4 by embedding groups of micro-sized rectangular metal inclusions, each group functioning as antenna elements and collectively functioning as an antenna array. The monolithic GDRA array mitigates the problem of individual element misalignment over the feed slots while providing precise interelement spacing. GDRA prototypes with 4 × 4 and 8 × 8 array elements fabricated and tested at 60 GHz demonstrate a −10 dB impedance bandwidth of 10.4% and 12.0% with broadside peak realized gain of 15.2 and 19.4 dBi.

A wideband dielectric resonator antenna array using air‐bridgeless coplanar waveguide power divider

In this communication a 2 × 2 dielectric resonator antenna (DRA) array is proposed with a wideband frequency response. An air bridgeless coplanar waveguide (CPW) power divider network is first time used to feed the 2 × 2 DRA array. Four rectangular DRAs are used as array element and exited in TE111 mode by four slots at the end of the CPW lines in the feed network. The straight CPW phase delay line in feed network is further meandered resulting an enhanced radiation performance. The proposed DRA array exhibits a wideband response with an impedance bandwidth of 16% while maintaining a stable broadside radiation pattern with the gain range from 8 to 9.4 dBi. The proposed design is fabricated and measured, reaching good agreement with simulation results.

Ultra-Wideband Dielectric Resonator Antenna Design Based on Multilayer Form

In this paper, an ultra-wideband dielectric resonator antenna (DRA) is investigated. It basically covers the bandwidth from 6 GHz to 16 GHz and achieves a relative bandwidth of 90.9%. It is found that a wide bandwidth can be reached with a small DRA by adopting multilayer form. Thus, the dimension of the designed DRA element which is composed of nine-element phased-scanning linear array is as small as 6.9mm x 8.2mm x 11 mm. While the maximum stable zenith gain is 6.2dB, the lobe width is 3 dB. The operating frequency range of the antenna array is from 5.42GHz to 16.5GHz, achieving a 101.1% relative bandwidth. A large scanning angle of ±60° is realized within the operating frequency band, with good scanning pattern and cross polarization. To verify the design and simulation, a 1 × 9 DRA array is fabricated, and measurements are carried out.

Suppression of mutual coupling in rectangular dielectric resonator antenna arrays using Epsilon-Negative metamaterials (ENG)

ABSTRACTA double slotted symmetrical split ring resonator with an inductive stub in its inner ring is presented as a Single Negative Electric (SNG) metamaterial to suppress mutual coupling between two E-plane coupled microstrip line fed rectangular dielectric resonator antenna (RDRA) array. The proposed SRR exhibits two resonant frequencies and wide stop-bands. The -10 dB bandwidth of S21 from 2022MHz to 2720 MHz and from 2187 MHz to 3839 MHz are obtained for the first structure, #1, and the second structure, #2, respectively. By introducing an ENG layer between the two RDRAs, the experimental reduction in mutual coupling is more than 23 dB with a small frequency shift (∼ 20 MHz), while the impedance matching is improved. The radiation efficiency and total efficiency are increased while the far-field pattern in the E-plane is not disturbed.

Capacitive Coupled Frequency Independent Dielectric Resonator Antenna Array for X-Band Applications

A capacitive coupled Dielectric Resonator Antenna (DRA) array based on log periodic technique is investigated experimentally for X-band applications. The Frequency Independent DRA array consists of seven rectangular Dielectric Resonators (DRs). The DRA array has been excited by a series fed microstrip line. Since the resonators are directly coupled to the feed line, it results in more compact and lower loss DRA array. The proposed DRA array has been designed and realized. The measured results are in good agreement with the simulations. The designed array is operating over the frequency range 6.2–12.2 GHz for 2:1 VSWR with the fractional bandwidth 65.2%. The array provides a peak gain of 9.09 dBi with the broadside radiation pattern over the widespread operating band. The proposed design is useful for X-band applications.

A Simple Decoupling Method for 5G Millimeter-Wave MIMO Dielectric Resonator Antennas

A simple decoupling method of using metallic vias to improve the isolation of millimeter-wave multiple-input-multiple-output (MIMO) dielectric resonator antenna (DRA) elements is investigated. The vias are vertically added to the DRA elements, at appropriate positions. By means of the interaction with the electromagnetic fields, the vias can potentially affect the filed distributions and further reduce the coupled fields effectively. The isolation between the MIMO DRA elements can, therefore, be enhanced substantially. As the vias are placed inside the DRA elements, no extra footprint is needed, making the entire antenna system very simple and compact. Two typical examples, including an H-plane and an E-plane, coupled $1\times2$ MIMO DRA arrays, have been designed, fabricated, and measured to demonstrate the feasibility and universality of this method. The results show that by using the vias appropriately, the isolation of the H-plane coupled MIMO DRA array can be enhanced from ~15.2 to 34.2 dB, while that of the E-plane array can be improved from ~13.1 to 43 dB at 26 GHz.

Wideband Circularly Polarized Dielectric Resonator Antenna Array With Polarization Diversity

In this paper, a design approach for aperture coupled modified cylindrical dielectric resonator antenna (cDRA) array is discussed. The proposed radiating element is dual cylindrical ceramic blocks placed with a small gap. The proposed aperture excites dual radiating mode pattern inside modified cDRA, i.e., HEM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11δ</sub> and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01δ</sub> . The arrangement of radiating elements, i.e., dual cylindrical ceramic blocks, provides lower Q-factor (wider impedance bandwidth). Conversion from a single radiating element to an array arrangement provides the gain enhancement of 3.0 dBi in the complete operating frequency range. The proposed aperture offers circularly rotating EM wave within frequency range 4.5-5.7 GHz. Antenna prototype is fabricated for the validation of simulated near as well as far-field parameters. Practically measured outcomes confirm that it is working in between the frequency range 4.7-6.4 GHz. The 3-dB axial ratio bandwidth of the proposed radiator is about 23.52% (4.5-5.7 GHz). Directional radiation pattern and circular polarization features make the proposed radiating structure more appropriate for WLAN (5.2 GHz) and local thermal equilibrium (LTE) band 46 (5.5 GHz) applications.