Showing papers presented at "International Workshop on Antenna Technology in 2018"

Overview of antenna designs and considerations in 5G cellular phones

Abstract: The paper for the invited talk presents a quick understanding and an overall picture on the major antenna designs and considerations in the fifth generation mobile communications (5G) cellular phones. Due to the significant differences in the electromagnetic (EM) behaviors and communication requirements for different 5G frequency bands, the frequency boundary is set at 6 GHz to clearly classify the antenna designs and considerations in 5G cellular phones into the ones for sub-6 GHz and above 6 GHz, i.e. the mm-Wave, respectively. From 1G to 5G sub-6 GHz, the main evolutions and challenges in antenna designs for cellular phones are principally driven by the “quantity increase”, such as the band quantity increase and the antenna quantity increase. However, for cellular phone antenna designers, 5G mm-Wave antenna designs, instead, are radical changes or a revolution.

Design of a dual-band MIMO antenna for 5G smartphone application

Abstract: A Dual-band MIMO antenna for the 5G communication is proposed in this paper. The proposed antenna consists of four antenna, it operating at 3300–3600 MHz and 4800–5000 MHz. The antenna designed in this letter are different from traditional 5G antennas, the antenna of this paper is perpendicular to the edge of the system circuit board, it can be applied to the popular full-screen mobile phone. According to the simulation results, reflection coefficient of the modulus is less than −6 dB, and the isolation is better than 12 dB over the band-frequency of 3300–3600 MHz and 4800–5000 MHz, it will met the needs of future 5G applications.

Development challenges for 5G base station antennas

Abstract: This paper presents mainly the challenges in the development of base station antennas for the fifth-generation (5G) wireless system. As one of the key technologies, Massive Multiple-Input Multiple-Output (M-MIMO) system can provide huge improvements in terms of system capacity and have been proven both in theory and practical network. The antenna element in the M-MIMO array is discussed at first, and then the multi-system antenna for 5G which is compatible with 4G/3G is involved. As the most important part, three different ways to generate multibeams is presented in details. At the end, the antenna testing method and new material requirement are mentioned.

PLA-based 3D printed circularly polarized X-band horn array antenna for CP-SAR sensor

Abstract: This paper presents a polylactid-acid (PLA) based 3D printed circularly polarized 2 × 2 X-band horn array antenna for circularly polarized synthetic aperture radar (CP-SAR) sensor. The use of CP horn array antenna is to overcome some issues related with mismatch orientation and ionospheric effect of linear polarization sensor. The proposed array antenna which is intended to operate at X-band frequency is realized using PLA material through 3D printing technique and fed by series sequential feeding network implemented on a 1.6mm thick NPC-F220A dielectric substrate. From the result, it shows that the proposed CP horn array antenna has 3dB axial ratio bandwidth more than 400MHz in X-band frequency range.

Eight-element MIMO antenna array for 5G/Sub-6GHz indoor micro wireless access points

Abstract: An eight-element multiple-input multiple-output (MIMO) antenna applied for 5G and sub-6GHz indoor wireless access points is studied in this paper. The proposed antenna array supports 4 × 4 MIMO in the LTE bands 42/43/46 (3400–3600 MHz, 3600–3800 MHz, and 5150–5925 MHz). Four fork-like electric dipoles disposed at the corners of the system circuit board cover the LTE bands 42/43, while four inverted L-shaped open slots placed along the edges support the LTE band 46. The proposed antenna array exhibits good impedance matching and isolation, with return losses greater than 10 dB and isolations larger than 15 dB. The total efficiency of the antenna array is higher than 70% in the desired operation bands. The envelope correlation coefficient (ECC) and ergodic channel capacity are calculated to verify the MIMO performance.

High performance 5G millimeter-wave antenna array for 37–40 GHz mobile application

Abstract: In this paper, a high performance 5G millimeter-wave phased antenna array for 37–40 GHz mobile application is proposed. The proposed antenna array is based on dipole antenna with two opening holes. It is shown that compared to previous designs our antenna array design has good antenna performance in terms of antenna gain and scanning property within the entire frequency range.

A wideband implantable antenna for 2.4 GHz ISM band biomedical application

Abstract: In this study, a single-fed wideband implantable antenna that operates at the 2.4 GHz ISM band is designed for biomedical applications. The impedance bandwidth enhancement is achieved by combining two modes. One is the fundamental mode of center microstrip antenna, and anther additional mode is attained by the outside loop. The simulated impedance bandwidth and radiation patterns are studied in a cubic skin phantom. The simulated impedance bandwidth below −10 dB ranges from 2.24 to 2.59 GHz (35%). The proposed antenna mainly radiates in the off-body direction and has a peak gain of −20.8 dBi at boresight. The influence of dielectric properties and implant depth are also discussed. The sensitivity studies indicate the stability of our antenna.

A low-cost dual-polarized 28 GHz phased array antenna for 5G communications

Abstract: A dual-polarized patch array antenna operating at 28 GHz is designed for 5G communication applications. Based on the conventional PCB process, the antenna is suitable for the phased array module integration, and it can support both horizontal and vertical polarizations. For the single antenna element, it achieves simulated average return loss of less than 10 dB, gain of about 6 dBi from 25 to 30 GHz. In addition, the isolation between the horizontal and vertical polarizations is lower than −20 dB. For the phased array antenna, the simulated peak gain at broadside and 30 degree is 17.6 and 14.6 dBi, respectively. Furthermore, 4 identical 2×2 element subarrays are arranged with special configurations, improving the antenna arrays' cross-polarization suppression and avoiding undesired sidelobes.

An broadband transparent metamaterial absorber using an ITO resistive-film

Abstract: A broadband two-layer transparent metamaterial unit is proposed as a absorber at X-band, Ku-band and K-band. The transparent soda-lime glass and indium tin oxide (ITO) film were used to design the transparent metamaterial absorber unit. In the case of both TE-polarization and TM-polarization, a high absorption, more than 90%, is shown in the frequency range of 8.1GHz to 28.7GHz. The thickness of the metamaterial absorber unit is 3.3mm. The metamaterial absorber unit has wide incident angle stability and high transparency. It can be widely used in all kinds of household appliances in order to reduce the electromagnetic radiation because the structure is transparent in the visible light band.

Slot-based connected antenna arrays for 5G mobile terminals

Abstract: The fifth generation (5G) of wireless communications will utilize the millimeter-wave (mm-wave) spectrum to achieve higher data rates to mobile users. The design of antenna arrays for mm-wave enabled mobile terminals requires wide bandwidth, good efficiency and high gain to combat free-space path loss. In this work, we present an attractive very compact in size antenna array design utilizing the concept of connected antenna arrays (CAA). CAA present wideband antenna responses that can be very suitable to mm-wave applications as well as provides more compact antenna sizes that can be integrated within mobile terminals compared to conventional ones. A slot based CAA is proposed in this work for standard mobile handset size terminals that includes a 4G as well as a 5G mm-wave antenna systems. The 4G bands covered are between 1.8–3.1 GHz while the 5G band covered is between 27.2–28.5 GHz.

A substrate integrated waveguide slot antenna for 79-GHz applications

Abstract: A substrate integrated waveguide (SIW) slot antenna for 79GHz applications is proposed in this paper. In order to get the high gain and lower losses, the antenna is designed as a sub-array composed with eight slots, which fabricated in the wide side plane of the SIW, and placed along the central axis with the equal interval of half waveguide wavelength. The slots can radiate the electromagnetic energy through the field disturbance caused by the plated-through hole (PTH) positioned beside the slots. The antenna is fed by the 50 u coaxial-fed structure located from the bottom of SIW. This bottom-fed method is different from the traditional microstrip feeding method, it has more convenience to extend the 2-dimensional phased array through multiple independent subarrays in the 79-GHz applications. The simulated results of the subarray indicate that the frequency band with |S11|<−10dB is from 78GHz to 80GHz, and the cross-polarization is lower than −50dB. An array model with 3×5 subarrays is also fabricated and simulated, it is found that the array radiation efficiency can be evaluated larger than 80%, and the patterns are also extremely well qualified. The performances confirm that the proposed SIW slot antenna is suitable for the millimeter-wave electronic systems with the requirement of array antenna.

Integration of electro-textile RF coil array with magnetic resonance imaging (MRI) system: Design strategies and characterization methods

Abstract: Radio Frequency (RF) coils are used to receive the magnetic RF signal from the human body during MRI scanning. In this paper, electro-textile will be used to design MRI RF coil array. The coil array incorporating the transmission decoupling circuitry are tuned together with the loading phantom. The S 11 = − 30dB and S 21 = −16dB at exactly the required resonant frequency of 127.7 MHz by 3T MRI scanners are achieved. The measured quality factor is related to the relative SNR to predict of electro-textile RF coil SNR performance. A microstrip line method is used to measure the effective conductivity of the electro-textile patterns. It is studied that electro-textile coils whose effective conductivity are two orders of magnitude lower than the copper can still achieve the SNR of around 50% of the copper coil. The RF coil array is made with non-magnetic components and is integrated with pre-amplifier interface for the final integration with MRI systems.

A new 2×4 array design of dual-band millimeter-wave antenna for 5G applications

Abstract: A new 2×4 array for dual-band milllimeter wave (mm-wave) antenna operating at 28 GHz and 38 GHz has been designed and evaluated in this paper. The proposed antenna array consists of 8 elements with 8 ports in 2×4 square configuration. Dual-band characteristic was produced using slotted patch method. At these frequencies, we also compared the antenna gain between waveguide and SMA port feed techniques. It shows that the gain of antenna array with SMA port reaches 15.8 dBi at 28 GHz and 13.9 dBi at 38 GHz, respectively. There was a slight decrease of antenna gain with SMA port compared to that of the waveguide feed. All the 8 antenna-elements shows a very consistent return-loss (S11) characteristics, in that they have almost identical bandwidth to cover 28 GHz and 38 GHz. Also, each element has a very good isolation between each other, i.e the protection between their feeding point is more than 28.692 dB at 28 GHz and 38.779 dB for 38 GHz, which can meet the inter-element protection requirements.

A planar multiband antenna based on CRLH-TL ZOR for 4G compact mobile terminal applications

Abstract: A planar multiband antenna based on composite right-and-left-handed transmission line (CRLH-TL) zeroth-order resonator (ZOR) for 4G compact mobile terminals is proposed in this letter. The proposed antenna consists of a monopole, a CRLH-TL structure and a triangular radiation patch. Among them, the monopole antenna can cover GSM850/950 (824–960 MHz) and LTE2500 (2500–2690 MHz); capacitive excitation of the CRLH-TL structure can produce ZOR mode to cover LTE band 12 (698–746 MHz); triangular radiation patch can cover high-frequency DCS, PCS, UMTS, LTE2300 (1710–2490 MHz). Since the antenna has the advantage of multiband, compact size and ease to fabricate, it can be applied to design 4G compact mobile terminals.

A new H-slot coupled microstrip filter-antenna for modern wireless communication systems

Abstract: This article describes a new H-slot coupled microstrip filter-antenna. In the antenna design, these microstrip lines are used to feed H-shaped coupling slots on the grounded metal plane. The H-shaped coupling slots feed top radiating patches, which can realize the radiation function of the antenna. The bilateral power divider is connected with the microstrip line, and realize the filtering function. The antenna has a bandwidth of 0.78 GHz from 3.02 to 3.8 GHz. In the frequency band of 3.4 to 3.6 GHz, the average gain in the direction perpendicular to the antenna plane has exceeded 11 dBi.

A novel monitoring technique for breast cancer hyperthermia using thermoacoustic imaging

Abstract: A novel real-time monitoring method is presented based on thermoacoustic imaging for applications in breast cancer hyperthermia. In the proposed technique, thermoacoustic imaging combined with compressive sensing is implemented to improve monitoring efficiency. Numerical modeling work is done using a breast phantom, which has realistic dielectric properties and internal structures, to validate feasibility of the presented technique. Results of the modeling work clearly show the effectiveness of the monitoring method. This technique can also find applications in other types of hyperthermia.

Unequally spaced linear antenna arrays synthesis based on genetic algorithm

Abstract: The analysis for the assembling of non-uniform, linear arrays based on Genetic Algorithm is presented. The GA optimization techniques generate the locations of the elements for reducing the side-lobe level. Results are presented for the placement of 20 elements under the design of a 15.5 λ. linear array. The scanning properties of the designed arrays are also investigated. According to the optimized results, patch antenna arrays are simulated by Ansys HFSS software to verify the optimization technique.

Design of dual-band metasurface antenna

Abstract: A metasurface antenna is proposed for the dual-band operation in 5G millimeter systems. The metasurface consists of a single-layered square patch array excited by two microstrip feeding slots cut onto the bottom ground. The characteristic mode analysis is used to optimize the metasurface patterns for the dual-band operation. The modes of metasurface resonant at 30 GHz, 38 GHz, and 41 GHz, respectively. To broaden the bandwidth, the etched slots on the ground are resonant as well. The impedance is matched over the frequency ranges of 23.75–28.8 GHz and 36.22–40.5 GHz with return loss larger than 10 dB. The simulated gain reaches 8.8–10.17 dBi and 9.46–12.6 dBi over the operating bands, respectively.

Fabrication and reliability evaluation of passive UHF RFID t-shirts

Abstract: In this paper, we present textile antennas fabricated for T-shirt RFID applications by cutting from commercially available electro-textile, by sewing with conductive thread, and by 3D printing with stretchable silver ink on a 100 % cotton fabric. The ready tags with attached ICs are coated with a protective stretchable encapsulant. The wireless performance of the T-shirt tags is evaluated initially as well as after seven washing cycles, followed by nine washing-drying cycles in a household washing and drying machines. The initial read ranges of all kinds of tags, when measured on-body, are around 3.5 meters. Based on the reliability testing results, the coating effectively protects the components from cyclic washing and drying.

A compact triple wideband-notched UWB antenna

Abstract: A compact ultra-wideband (UWB) antenna with triple wideband-notched characteristic is presented. The three notched wide bands are respectively obtained by loading U-shape slot, L-shape stubs, and nested semielliptical slots on the ground plane with a rectangular slot and a hexagon patch, which is fed by a coplanar waveguide (CPW). The simulated results show that the antenna achieves the 10dB impedance band from 2.7 to 10.7 GHz in which three notched wide bands of 3.3∼3.8 GHz, 4.75∼5.9 GHz, and 7.25∼8.4 GHz for return loss (RL) less than 10 dB are obtained. The z-direction gains of the antenna at the operating frequencies of 3.1, 6.7, 9 GHz are larger than 2.7, 2, 4.4 dBi, respectively. While the z-direction gains of the typical frequencies of 3.4, 5.2, 7.8 GHz in the three notched bands are −7.5, −6, −9dBi, separately. The surface current distributions at the operating frequencies and the typical notched frequencies are presented for verifying the design method and principle of the antenna. Consequently, the mutual interference between the narrowband systems of WiMAX/WLAN/5G/X-band satellite communication and UWB communication system can be reduced significantly. Moreover, the design has the smaller size of 26×25 mm2, compared with existing triple band-notched UWB antennas. Therefore, the antenna is very promising for modern UWB communication applications.

A high-gain dielectric resonator antenna array fed by back-cavity

Abstract: A circularly polarized dielectric resonator antenna (DRA) millimeter wave array (MMW) with cavity-backed substrate integrated waveguide (SIW) feeding is proposed. This antenna is excited by a coaxial probe. The implemented antenna exhibits a simulated gain of almost 16 dBi and good radiation efficiency of around 96% are also obtained. The best axial ratio is almost less than 0.5 dB. It shows a good performance in radiation pattern.

Dispersion reduced SIW leaky-wave antenna by loading metasurface prism

Abstract: Leaky-wave antennas (LWAs) are well-known for the high directivity, wide impedance bandwidth, and the beam-scanning performance with frequency. However, in the system that requires high-speed data transfer, wide system band and high directivity, LWAs are struggling with their beam squint effect in the radiation patterns, which limits their applications. In this paper, a dispersive metasurface prism is loaded to a dispersive LWA, reducing the LWA's dispersion, to make the LWA wide band radiating at a specific direction. A substrate integrated waveguide (SIW) LWA is taken to demonstrate the proposed concept with metasurface prism implemented by metallic vias. Full-wave simulation results show that the proposed low-dispersive SIW LWA has the main radiating direction at φ=24°, with half-power beamwidth of 8°, steers only ±0.5° from 33 to 38 GHz.

Performance testing of MIMO device with the wireless cable method based on particle swarm optimization algorithm

Abstract: Wireless cable method is a strong candidate to replace conductive cable method for performance testing of multiple-input multiple-output (MIMO) devices. Desired testing signals can be guided over-the-air to the corresponding antenna ports of the mobile terminals, via implementing a compensation filter in the channel emulator (CE). A novel wireless cable method, without the knowledge of transfer matrix between the CE output ports and device antenna ports, was recently proposed in the literature. In this method, the compensation filter was determined based on the average power recorded by each device antenna ports. To speed up the calibration procedure, a one-dimensional monotonic search method was proposed. However, the calibration accuracy was lower comparing with the brute-force method. In this paper, a high-efficiency particle swarm optimization (PSO) algorithm is proposed to determine the compensation filter. Numerical simulation results are provided to validate the effectiveness of PSO algorithm for compensation filter determination in the wireless cable testing.

3D thermoacoustic imaging based on compressive sensing

Abstract: This work reports our recent progress in 3D thermoacoustic imaging based on compressive sensing. Thermoacoustic imaging has been extensively research in the past 15 years and has developed numerous applications especially in biomedical engineering. Pursuing a fast data measurement in the experimental process of thermoacoustic imaging is very meaningful. Compressive sensing based 3D thermoacoustic imaging technique holds great promise to achieve this goal. Detailed procedure of the novel method is introduced. Simulation results show that only 10 measurements are enough to obtain a good thermoacoustic image of four spherical objects.

Generation of conical beam by reflective metasurface

Abstract: We use the phased-array model to theoretically analyze the conical beam-shaping. It shows that the cone angle of the conical beam can be arbitrarily controlled by just changing the initial phase excitation distribution on the array. Based on this mechanism, a passive reflective metasurface is designed to generate conical beam with certain cone angle. The metasurface element, designed based on the concept of geometric phase, is composed of two orthogonal I-shaped metallic structures etched on a back-grounded dielectric substrate. Under the normal illumination of left-circularly polarized incidence, left-circularly polarized conical wave can be obtained at 15.5 GHz with a cone angle of 13.6 degree. Simulation and measurement are carried out to validate the theoretical prediction, which show good agreement with each other.

A frequency and polarization reconfigurable frequency selective surface based on liquid crystal

Abstract: In this paper, a new type of frequency and polarization reconfigurable FSS (Frequency selective surface) is designed. By using liquid crystal material, the frequency of the FSS can be reconfigured. The dipole sub-module is used. The upper and lower dipoles separated by the dielectric substrate are orthogonal to each other. The adjacent short-term dipole passes PIN diodes connected, and the switch of the dipoles controls the polarization selection of FSS in the passband. The experimental results show that the FSS can select the TE and TM waves, and the polarization selection and reconfiguration characteristics are obvious.

Compact triple-band circularly-polarized directional antenna for UHF/ISM RFID mobile readers with GNSS band

Abstract: Multi-band, multi-function, and miniaturization are very desirable for late-mode wireless mobile devices. In this paper, a compact triple-band circularly-polarized directional antenna at 920MHz, 1600MHz, and 2450 MHz is proposed for UHF/ISM RFID mobile readers with GNSS band. The antenna consists of a two-feed network and stacked radiating patches. Measured result shows that the 10 dB impedance bandwidths are 24, 430, and 340 MHz with 3-dB axial ratio bandwidths of 13, 230, and 365 MHz for the three bands. In these bands, the antenna provides the symmetric radiation patterns and the peak gains of 3.7, 6.6, and 8.8 dBic, respectively. Comparison shows that the antenna not only features compact size, simple configuration, and low cost but also provides wide CP bandwidths. Moreover, the operating frequencies can be changed conveniently and the large frequency ratio of 2.8 is achieved. It is the first design to integrate the UHF/ISM RFID reader application and GNSS function into a single antenna.

DOD and DOA estimation for bistatic MIMO radars with sparse Bayesian learning

Abstract: A sparse Bayesian learning (SBL) based method with a novel grid deriving strategy is proposed in this paper for joint direction of departure (DOD) and direction of arrival (DOA) estimation in bistatic MIMO radars. Directly applying compressed sensing methods to MIMO radars leads to a heavy computational load because of high dimensional matrix operations. To solve this problem and improve the estimation accuracy, we first construct a coarse grid with some proper initializations, and then resorts to an off-grid SBL model to handle the off-grid gap, where an expectation-maximization (EM) algorithm is utilized iteratively for grid refining aiming to narrow the gap between the true and the estimated DOD and DOA. Simulation results verify the efficiency of the proposed method.

A high gain Fabry-Perot cavity antenna designed by modified ray tracking model

Abstract: A high gain Fabry-Perot cavity antenna (FPCA) designed by modified ray tracking model(MRTM) is presented in this paper. In particular, the conventional ray tracking is modified in order to calculate the electric field distribution on the partially reflective surface(PRS). Furthermore, the dependence of the magnitude of PRS reflection coefficients on aperture efficiency is studied, which shows that an optimal magnitude exists on aperture efficiency for a fixed size FPCA. By using the optimized reflection coefficient, a final compact single layer FPCA with a dimension of 6.25λ 0 × 6.25λ 0 and a profile of 0.5λ 0 is designed. The proposed antenna can reach a peak gain of 24.0dBi at 12.5GHz and an aperture efficiency of 51.2%.

Compact meander-slot DGS for MIMO antenna with high isolation

Abstract: This letter presents a meander-slot defected ground structure (DGS) for a two-element multiple-input-multiple-output (MIMO) antenna with high isolation. The two-monopole MIMO antenna operates at 1.8 GHz. The reduction of mutual couplings between the monopoles is achieved by suppressing the surface waves on the ground plane using the meander-slot DGS. The designed DGS has a very compact size of 10mm ×14 mm (0.06λ×0.08λ) suitable for practical design of MIMO antenna.