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In this paper, a wideband and bandwidth-controllable hybrid-glass dielectric resonator antenna (DRA) excited by a probe platform is proposed. The proposed hybrid-glass DRA simply consists of a probe platform and a solid cylindrical glass DRA unit, making the fabrication easier. The probe mode and the TM01δ mode of the cylindrical glass DRA are employed to design the wideband antenna. It is found that the impedance bandwidth of this hybrid-DRA can be controlled by the height of the glass DRA in a wide range of ~23%-70%, without changing the size of the feeding. Engineering formula considering the bandwidth has been given to facilitate the design. To demonstrate the idea, three wideband hybrid-glass DRAs with their measured impedance bandwidths of 39.5%, 56.6% and 74% have been designed. To upgrade the three hybrid-glass DRAs as the artistic antennas, laser-engraving patterned glass is employed to do the fabrication again. The measured results show that the performance of the hybrid-glass DRAs with and without patterns are basically the same.

In this paper, a slots-coupled omnidirectional circularly polarized (CP) cylindrical dielectric resonator antenna (DRA) is proposed. The TM $_{01 \delta }$ and TE $_{\mathrm {011+\delta }}$ modes of the cylindrical DRA are simultaneously excited by four printed slots placed at 45 degrees to the radial direction. Omnidirectional CP fields are obtained when the fields of the two modes have the same amplitude and 90 degrees phase difference. Compared with the traditional probe-fed method, the structure of the proposed slots-coupled DRA is very simple, without introducing any groove, patch, choke or shorting pins. For the demonstration, a slots-coupled omnidirectional CP cylindrical glass DRA is designed for 5.8-GHz WLAN application. It is found that the proposed DRA can provide an AR bandwidth of ~8% (5.62-6.09 GHz) and a gain of ~5.6 dBic, with a height of $\sim 0.127\lambda _{0}$ . This performance is competitive with other reported omnidirectional CP DRAs.

Design of the wide dual-band rectangular souvenir dielectric resonator antenna (DRA) is discussed. The proposed wide dual-band rectangular DRA was excited by using a U-slot. The $TE_{111}{^{\mathrm {y}}}$ mode of the rectangular DRA and the slot resonator were employed to design the lower band, while the higher-order $TE_{113}{^{\mathrm {y}}}$ and $TE_{311}{^{\mathrm {y}}}$ modes were utilized to design the upper band. By merging two pairs of modes in each band, the impedance bandwidth of the lower and upper bands were enhanced simultaneously. New design formulas that determine the dimensions of the wide dual-band rectangular DRA were obtained. Design guideline was also given to facilitate the design. To demonstrate the usefulness of the formulas, a wide dual-band rectangular DRA fabricated using K-9 glass was designed for 2.4/5.2-GHz WLAN applications. To upgrade the antenna as the souvenir-DRA, the word “LOVE” was carved on the sidewall of the glass DRA by using the sandblasting machine, and it was found that the content and position of the word has little effect on the antenna performance. The impedance bandwidths of the proposed wide dual-band DRA can be achieved as ~25% for the lower band and ~13% for the upper band.

A broadband differential-fed dual-polarized hollow cylindrical dielectric resonator antenna (DRA) is proposed in this article. It makes use of the HEM111, HEM113, and HEM115 modes of the cylindrical hollow DRA. The proposed DRA is simply fed by two pairs of conducting strips and each pair of strips is provided with the out-of-phase signals. After introducing four disconnected air holes into the DRA, a broadband characteristic is achieved, with little effect on the antenna gain of its higher-order modes. To verify this idea, frosted K9-glass is applied to fabricate the hollow cylindrical DRA. The differential S-parameters, radiation patterns, and antenna gain of the DRA are studied. It is found that the proposed differential-fed dual-polarized DRA is able to provide a broad differential impedance bandwidth of ~68% and a high differential-port isolation better than ~46 dB. Moreover, symmetrical broadside radiation patterns are observed across the whole operating band. The proposed DRA covers the frequency bands including the 5G-n77 (3.4&ndash, 4.2 GHz), 5G-n79 (4.4&ndash, 5.0 GHz), WLAN-5.2 GHz (5.15&ndash, 5.35 GHz), and WLAN-5.8 GHz (5.725&ndash, 5.825 GHz), which can be used for 5G communications.

A wideband and replaceable dielectric resonant antenna (DRA) excited by a probe is investigated. The proposed wideband DRA consists of a probe platform and a solid cylindrical dielectric resonator, and two magnets are applied to fix them. In this way, the dielectric resonator can be easily replaced. Therefore, three kinds of wideband DRAs with impedance bandwidth of 35.8%, 56.6% and 74% are designed. The reflection coefficient, radiation mode and antenna gain of the cylindrical DRA were analyzed by using HFSS ANSYS.

The three-port polarization-diversity cylindrical dielectric resonator antenna (DRA) is presented for the first time. The design makes use of the TM 01δ and HEM 12δ+1 modes of the cylindrical DRA. Using the covariance matrix adaptation evolutionary strategy, engineering formulas are obtained to determine the dimensions of the polarization-diversity cylindrical DRA for a given operating frequency and dielectric constant. To demonstrate the usefulness of the formulas, a three-port polarization-diversity cylindrical DRA was designed at 2.4 GHz for WLAN applications. The TM 01δ mode of the cylindrical DRA is excited with a coaxial probe and an omnidirectional radiation pattern is obtained. Two slot pairs are used to excite the broadside HEM 12δ+1 x and HEM 12δ+1 y modes of the cylindrical DRA. The reflection coefficient, port isolation, radiation pattern, and antenna gain of the antenna were simulated using ANSYS HFSS, while the envelope correlation was calculated from the S-parameters. Measurements were carried out to verify the simulations, and reasonable agreement between them is observed. Measured results show that the isolation between any two ports of the diversity DRA is over 24 dB across the 10-dB impedance bandwidth. A parameter study was carried out to characterize the proposed DRA.

This communication investigates the wideband omnidirectional two-layer hemispherical dielectric resonator antenna (DRA), excited in its omnidirectional TM101 mode by an axial probe. For the first time, design formulas of the omnidirectional two-layer hemispherical DRA are found by using the covariance matrix adaptation evolutionary strategy (CMA-ES). The formulas are used to design a two-layer transparent hemispherical DRA which simultaneously serves as the covering of a light source. Acrylic and glass are used for the inner and outer transparent layers, respectively. ANSYS HFSS was used to simulate the DRA, and the simulation agrees reasonably well with our measurement. It was found that the transparent two-layer DRA has a measured impedance bandwidth of 31.9%, which is over two times wider than that of the single-layer TM101-mode glass DRA.

The dual-function glass dielectric resonator antenna (DRA) that simultaneously serves as a light cover is investigated for the first time. This paper is the first part, which demonstrates the idea using omnidirectional hollow rectangular glass DRAs. Both linearly polarized (LP) and circularly polarized (CP) designs are given. The glass DRA can generate CP fields by adding metallic patches onto its side walls, with a 3-dB axial ratio bandwidth of ~ 7%. To obtain an entirely light-transmissible CP glass DRA, conducting indium tin oxide (ITO) patches are used in place of the metallic patches. For each of the LP and CP designs, powered light emitting diodes (LEDs) are placed inside the hollow region of the glass DRA to serve as the light source. It is shown that practically the lighting and antenna parts do not interfere with each other. The reflection coefficient, axial ratio (CP designs only), radiation patterns, and antenna gains of the proposed LP and CP antennas are studied, and good agreement between measured and simulated results is observed.

This paper is the second part of our study that investigates using glass dielectric resonator antennas (DRAs) as light covers. To begin, designs of dual-band hemispherical DRAs are investigated for the first time. Both broadside and omnidirectional dual-band DRAs are included in the study. The former makes use of the broadside TE111 and TE112 modes of a hollow hemispherical DRA, whereas the latter utilizes the endfire TM101 and TM103 modes of a solid hemispherical DRA. New design formulas that determine the radii of the two dual-band hemispherical DRAs are found. To demonstrate the usefulness of the formulas, two dual-band hemispherical DRAs for WLAN/WiMAX applications were designed and fabricated using K9 glass. ANSYS HFSS was used to simulate the DRAs, and the results agree reasonably well with our measurements. Results of using the DRAs as light covers are reported.

This paper explains the basic characteristics of dielectric resonator antennas (DRAs), with emphasis on the effect of the form factor on their resonance (operating) frequencies. It is followed by discussions on their recent developments in higher order mode, circularly polarized, dual function, and transparent designs over the last few years. The idea of using glass DRAs as decoration antennas is proposed and demonstrated for the first time.

Linear-/circular-polarization designs of the dual-/wide-band cylindrical dielectric resonator antennas (DRAs) are presented. The HEM111 and HEM113 modes of the cylindrical DRA are utilized to design the dual-mode cylindrical DRA. A wideband antenna can be obtained by merging the two resonant modes. To facilitate the designs, new engineering formulas that determine the dimensions of the dual-mode cylindrical DRA are found for the first time. They are obtained by using the covariance matrix adaptation evolutionary strategy (CMA-ES). Design examples for the dual-/wide-band cylindrical DRAs are given for both the linearly and circularly polarized cases. Ansoft HFSS was used to simulate the DRAs and the simulations were verified with our measurements. Good agreement between the measured and simulated results is observed.

Designs of the single-, dual-, wide-band rectangular dielectric resonator antennas (DRAs) are discussed. Using new single-band formulas, the resonance frequency of the DRA can be determined easily from the given DRA dimensions and vice versa. Also, new formulas for designs of dual-mode rectangular DRAs are derived in this paper. From the derivation, the limit of the frequency ratio is also found and discussed. The formulas can be used to design a dualband DRA or a wideband DRA when the two resonance frequencies are close to each other. To validate our results, three single-, dual-, and wide-band rectangular DRAs were designed using the new formulas. In each case, the reflection coefficient, radiation pattern, and antenna gain were simulated and measured. Good agreement between the calculated, simulated, and measured results is obtained.

In this letter, a compact differential hollow dielectric resonator antenna (DRA) is investigated. The hollow DRA is fed by two identical conducting strips connected to the outputs of an underlaid 180° hybrid coupler (rat-race). With this compact configuration, loss of the feed network can be minimized and, thus, the differential gain can be made about the same as for the single-ended case. By using the differential feed, the DRA can be integrated with differential integrated circuits directly. Also, its cross-polarized fields are generally weaker than those of the single-ended version. The reflection coefficient, radiation pattern, and antenna gain of the proposed differential DRA are simulated, and the result agrees reasonably with our measurement.

One-dimensional (1D) semiconductor nanomaterials attract much attention because they are ideal systems for investigation and studying the relationship between properties and structures and having extensive application future in the high technical field. They are expected to play an important role in fabrication of the next generation nanocircuits, nanotools, nanowires lasers, photon tunneling devices, near-field photo-waveguide devices, etc. This article described controlled growth, characterization of structures and morphologies and properties of 1D semiconductor nanomaterials based on our previous works. This article is organized into two parts: The first part is complicated nanostructures of semiconductors, which includes coaxial nanocables, heterostructure nanowires and nanowires with metal–semiconductor junction behavior, hierarchical structures, doping of the nanowires and nanobelts, porous materials and periodically twined nanowires and asymmetrical polytypic nanobelts. The second part contains semiconductor nanoarrays based on anodic alumina membrane (AAM) templates. Finally, we propose that further investigation of the influence of nanomaterial morphologies on properties and how to design the morphology of nanostructures to meet the property requirements of nanodevices are our future research directions in this field.

A strip-fed wideband circularly polarized (CP) dielectric resonator antenna (DRA) is investigated in this paper. The wideband design makes use of the quasi-TE 111 and −TE 113 modes of the rectangular DRA. To generate CP fields, two opposite corners of the rectangular DRA are truncated at 45°. A groove and two parasitic strips are introduced to tune the axial ratio (AR) of the antenna. Measured results show that a wide AR bandwidth of 16.3 % can be achieved. The reflection coefficient, AR radiation pattern, and antenna gain of the DRA are studied using ANSYS HFSS. Reasonable agreement between the measured and simulated results is observed.

A singly-fed dual-band circularly polarized dielectric resonator antenna (DRA) is investigated in this paper. It makes use of the fundamental TE 111 mode and higher-order TE 113 mode of a rectangular DRA for the dualband design. The DRA has a square cross section. It is excited by a single microstripline-fed rectangular slot fed. To generate circularly polarized (CP) fields, two corners of the DRA are truncated at 45°, exciting two sets of degenerate orthogonal modes, namely (TE 111 x, TE 111 y) and (TE 113 x, TE 113 y). Measured results show that the axial-ratio bandwidths of the lower and upper bands are 5.2% and 1.4%, respectively. The reflection coefficient, axial ratio, radiation pattern, and gain of the antenna are studied using ANSYS HFSS. Measurements were carried out to verify the simulations and reasonable agreement between the measured and simulated results is observed.

An omnidirectional aesthetic dielectric resonator antenna (DRA) is investigated. The DRA, bought from the commercial market, is made of K-9 glass and is therefore transparent. It has a building shape and can be used for home or office decoration. To obtain an omnidirectional radiation pattern, the DRA is excited by a probe at the center of its bottom. The reflection coefficient, radiation pattern, and antenna gain of the antenna were measured, and a wide impedance bandwidth of 36.5 % is found.

Design of the dualband rectangular dielectric resonator antenna is presented. The fundamental TE 111 y mode and higher-order TE 113 y mode are used for the design, with their resonance frequencies controlled by changing the DRA dimensions. In this paper, the dielectric waveguide model (DWM) is used to calculate the resonance frequencies of the two modes. To demonstrate the idea, a dualband DRA for WiMAX and WLAN applications is designed. The reflection coefficient, radiation pattern, and antenna gain of the dualband DRA were simulated using Ansoft HFSS, and good agreement between the predicted and simulated resonance frequencies is obtained.

The strip-fed wideband notched rectangular dielectric resonator antenna is investigated in this paper. By simultaneously exciting the TE 111 y and TE 113 y modes of the DRA, a wide impedance bandwidth of 56% can be obtained, which entirely covers the WLAN (2.4–2.48 GHz) and WiMAX (3.4–3.7 GHz) bands. The reflection coefficient, radiation patterns, antenna gain and efficiency of the antenna were studied. Reasonable agreement between the simulated and measured results is obtained.

The single crystalline CdS nanobelts were synthesized by an improved vapor-liquid-solid (VLS) process. Field emission measurements show that the nanostructures have a low turn-on field of 3.7 V&m-1 at a current density of 10 μA cm-1, a low threshold field of 9.3 V μm cm-1 and a high enhancement factor of 1298. When assembled into nanoscale visible light photodetectors, the CdS nanobelts showed good sensitivity and wavelength selectivity. The results imply that the present CdS nanobelts are excellent candidates for applications in high-performance field emitters and photodetectors.

Thin and wide ZnO nanobelts doped with 5 atom % tin have been achieved under different flowing atmosphere. Photoluminescence measurements show a blue shift in the near band edge (NBE) emission spec...