Handset Antenna Research Articles

Hybrid Integration of 5G/B5G Millimeter-Wave and Microwave Antennas in Handsets for ISAC

Hybrid Integration of 5G/B5G Millimeter-Wave and Microwave Antennas in Handsets for ISAC

Alleviating User Interaction for Handset Antennas With Reactive Loads

Alleviating User Interaction for Handset Antennas With Reactive Loads

Handset antenna design optimisation and considerations for NTN applications

Handset antenna design optimisation and considerations for NTN applications

Estimation of Power Density in mm-wave Phased Array Antenna for 5G Cellular Handset

Estimation of Power Density in mm-wave Phased Array Antenna for 5G Cellular Handset

Analysis of Human Head Interaction in Handset Antennas Using Ground Plane Corrugation

Analysis of Human Head Interaction in Handset Antennas Using Ground Plane Corrugation

Self-Decoupled 8-Element Dual Polarized MIMO Antenna for B5G Handsets With Sub-6 GHz and mmWave Integration

Self-Decoupled 8-Element Dual Polarized MIMO Antenna for B5G Handsets With Sub-6 GHz and mmWave Integration

Design of Miniaturized Dual-Mode Antenna for Handset Terminal Communication

This paper presents a miniaturized dual-mode handset antenna design. A quadrifilar helix antenna (QHA) is utilized to work at higher band (1980-2010 MHz and 2170-2200 MHz) with circular polarization. By cutting off a circular slot on the outer conductor of the QHA feedline and introducing four quarter-wavelength short-circuited stubs, the QHA radiator and its feedline can also work as a monopole antenna at lower band (440-560 MHz) with linear polarization. With this radiator-sharing technique, the dual-mode characteristics can be achieved utilizing only a QHA; therefore, the antenna dimension can be reduced remarkably since it is unnecessary to design an additional monopole antenna. Moreover, the short-circuited stubs are designed with stripline and integrated with the one-to-four power divider and phase shifter for further miniaturization. The measured S11 is less than -8 dB. The typical gain is higher than 0.5 dBi at lower band and 2.5 dBi at higher band. The AR of the QHA is better than 1.3 dB, and the head SAR values are much lower than the international standard at both lower and higher bands. The proposed miniaturized dual-mode antenna can be applied to portable handsets to realize the intercom and satellite communications.

Integrated Design of Multimode and Multifrequency Miniaturized Handset Antenna at VHF/UHF Bands

This paper presents an integrated design of a multimode and multifrequency miniaturized handset antenna working at the lower band (0.24–0.7 GHz) with linear polarization and higher band (1.98–2.01 GHz and 2.17–2.20 GHz) with circular polarization simultaneously. At the higher band, the quadrifilar helix antenna (QHA) is utilized with each arm developed into two arms of different lengths and linearly tapered widths to realize double resonance and increase the bandwidth. Moreover, a helical stub behaving as a director is introduced to improve the antenna gain. At the lower band, the outer conductor of the QHA feedline and four QHA arms are designed to constitute a monopole antenna through proper feeding and introducing four quarter-wavelength short-circuit stubs. With this radiator-sharing technique, the QHA not only works at the higher band with a circular polarization pattern but can act as a monopole antenna working at the lower band with a linear polarization pattern simultaneously. As a result, the size of the antenna can be reduced remarkably. Finally, the proposed antenna is fabricated with a total length of 228 mm and a diameter of 15 mm. At the lower band, the measured S11 is below −8 dB, and the gain is larger than 0.5 dBi. At the higher band, the measured S11 and AR are better than −13 dB and 3 dB, respectively, and the gain within the zenith angle range of 0°−35° is greater than 2.5 dBi, which demonstrates better performance.

Impacts of Real Hands on 5G Millimeter-Wave Cellphone Antennas: Measurements and Electromagnetic Models

Penetration of cellphones into markets requires their robust operation in time-varying radio environments, especially for millimeter-wave communications. Hands and fingers of a human cause significant changes in the physical environments of cellphones, which influence the communication qualities to a large extent. In this paper, Referential cellphone antenna arrays at 28 and 39 GHz are designed, and then simplified electromagnetic models of them for simulations are developed. Their radiation properties are evaluated through near-field scanning of the two prototypes in free space, first for de-embedding the feedline loss of cellphone antennas. The similarity of radiation patterns between simplified models and cellphone mock-ups ensures the reliability for comparing simulated and measured results involving real-hand effects. Next, hand-antenna-interaction radiation measurements are set up so that we validate radiation performance simulations that use computational models of real hands that are generated by the approach in [1] and cellphones, by carrying out measurements of the same real hands and cellphone mock-ups and comparing measured to simulated results, which we show to agree well. This enables future research and development of mm-wave handset antennas relying on realistic simulations during the design phase.

ANALYSIS OF 5.8GHZ HELICAL ANTENNA FOR THE APPLICATION OF UNMANNED AERIAL VEHICLE

An Unmanned Aerial Vehicle (UAV) is an aircraft with practically no human pilot. The real life utilizations of UAV are payload conveyance, trafc checking, moving items in apparently perilous climate and with the end goal of observation in armed force, naval force and ying corps. The parts utilized in UAV's are Radome, Antenna, Antenna handset regulator, Modulation and recurrence transformation unit, Data interface unit, Power control module, Lithium battery and Solar power band. The antenna are the main electronic parts of UAV. The antenna utilized in UAV are Patch antenna, Spiral antenna, SATCOM antenna, MFC antenna, Array antenna, Blade antenna and L-C Sector antenna and Helical antenna. Helical antenna is planned in the recurrence of 10GHz and its exhibition attributes are examined for the compelling correspondence in UAV.

Decoupling Technique Using Ferrite-Film Loading for 5G MIMO Applications

Decreasing the mutual coupling between multiple-input-multiple-output (MIMO) antenna elements requires the selection of an appropriate decoupling technique without changing the geometry or operating frequency of the antenna. In this paper, a simple and flexible approach that involves loading a small ferrite film on the radiation patch of an MIMO antenna pair has been proposed to mitigate the unwanted mutual coupling. Through a thorough investigation, the two IFA elements with an element distance of only 1.4 mm can be decoupled adequately by properly controlling the ferrite-film loading area and the thickness of the ferrite film, along with maintaining the desired operating frequencies and acceptable radiation characteristics at the LTE Band 42 (3.4–3.6 GHz). The optimum ferrite-film loading on the grounding branch of the IFA element can increase the isolation from −6.64 dB to −10.43 dB and enhance the bandwidth from 3.20–3.88 GHz to 2.83–3.65 GHz, and its efficiency can reach to 45.5%, as well as a 2 dB gain. A physical model has also been established to interpret the operating mechanism of ferrite-film loading on the IFAs. The proposed simulated procedure is validated via measurements. This technique of ferrite loading on MIMO antennas can effectively decouple the mutual coupling at a low cost and with low design complexity, indicating its potential applicability for use in MIMO antennas in mobile handsets.

Fast Antenna and Beam Switching Method for mmWave Handsets With Hand Blockage

Many operators have been bullish on the role of millimeter-wave (mmWave) communications in fifth-generation (5G) mobile broadband because of its capability of delivering extreme data speeds and capacity. However, mmWave comes with challenges related to significantly high path loss and susceptibility to blockage. Particularly, when mmWave communication is applied to a mobile terminal device, communication can be frequently broken because of rampant hand blockage. Although a number of mobile phone companies have suggested configuring multiple sets of antenna modules at different locations on a mobile phone to circumvent this problem, identifying an optimal antenna module and a beam pair by simultaneously opening multiple sets of antenna modules causes the problem of excessive power consumption and device costs. In this study, a fast antenna and beam switching method termed Fast-ABS is proposed. In this method, only one antenna module is used for the reception to predict the best beam of other antenna modules. As such, unmasked antenna modules and their corresponding beam pairs can be rapidly selected for switching to avoid the problem of poor quality or disconnection of communications caused by hand blockage. Thorough analysis and extensive simulations, which include the derivation of relevant Cramér-Rao lower bounds, show that the performance of Fast-ABS is close to that of an oracle solution that can instantaneously identify the best beam of other antenna modules even in complex multipath scenarios. Furthermore, Fast-ABS is implemented on a software defined radio and integrated into a 5G New Radio physical layer. Over-the-air experiments reveal that Fast-ABS can achieve efficient and seamless connectivity despite hand blockage.

Investigation on Beam Alignment of a Microstrip-Line Butler Matrix and an SIW Butler Matrix for 5G Beamforming Antennas through RF-to-RF Wireless Sensing and 64-QAM Tests.

In this paper, an intuitive approach to assessing advantages of beamforming in 5G wireless communication is proposed as a novel try and practical demonstration of importance of alignment between the transmitter’s and receiver’s beams working in millimeter-wave frequency bands. Since the diffraction loss of millimeter-wave signals matters seriously in propagation, the effects of the misalignment and alignment between beams need to be checked for, which was conducted with a horn antenna and the 4 × 4 Butler matrix which mimic the relationship of the base station and handset antennas. Designing and using the microstrip-line and the substrate integrated waveguide (SIW) Butler matrices, RF-to-RF wireless connectivity between the horn and the microstrip line beamformer as case 1 and the horn and the SIW beamformer as case 2, concerning the changing angle of the beam from either of the two Butler matrices, was tested, showing over 12 dB enhancement in received power. This direct electromagnetic link test was accompanied by examining 64-QAM constellations for beam-angle changing from −30° to +30° for the two cases, where the error vector magnitude in the QAM-diagram becomes less than 10% by beam-alignment for the changing angle.

A Planar Millimeter-Wave Resonator-Array to Sense the Permittivity of COP Film with the 5G Handset Back-Cover.

In this paper, a new sensor is developed to estimate the dielectric constant of Cyclo Olefin Polymer (COP) film utilizable for 5G mobile phones’ multi-layered back-cover. It is featured by the electrical characterization of the thin layer of the COP film at 28 GHz as the material under test (MUT) directly contacting the planar probe (which is an array of resonating patches) and a new meta-surface as metal patterned on the COP film inserted between the planar probe and the 5G multi-layered back-cover for enhanced physical interpretation of the data by way of impedance matching. In this approach to delving into the material, a thin and small meta-surface film with an area of 25.65 × 21.06 mm2 and a thickness of 55 μm is examined for applications to 5G mobile 28 GHz-frequency communication on the basis of the below −10 dB-impedance matching for the 1-by-4 array sensor. Along with this, the real and commercial handset back-cover is brought to the test. The proposed method presents the advantages of geometrical adequacy to the realistic 5G handset antenna configuration, the idea of impedance-matching via meta-materials, and the suitability of characterizing the film-type structure as compared to the open-ended coaxial waveguide, waveguide-to-waveguide and TX horn-to-RX horn free-space test methods.

Empirical Evaluation of a 28 GHz Antenna Array on a 5G Mobile Phone Using a Body Phantom

Implementation of an antenna array on a 5G mobile phone chassis is crucial in ensuring the radio link quality especially at millimeter-waves. However, we generally lack the ability to design antennas under practical operational conditions involving body effects of a mobile user in a repeatable manner. We developed numerical and physical phantoms of a human body for evaluation of mobile handset antennas at 28 GHz. While the numerical phantom retains a realistic and accurate body shape, our physical phantom has much simpler hexagonal cross-section to represent a body. Gains of the phased antenna array configuration on a mobile phone chassis, called co-located array is numerically and experimentally evaluated. The array is formed by placing two sets of 4-element dual-polarized patch antenna arrays, called two modules, at two locations of a mobile phone chassis. Modules are intended to collect the maximum amount of energy to the single transceiver chain. Spherical coverage of the realized gain by the array shows that the experimental statistics of the realized gains across entire solid angles agree with numerical simulations. We thereby demonstrate that our antenna evaluation method reproduces the reality and our phantom serves repeatable tests of antenna array prototypes at 28 GHz.

A frequency reconfigurable/switchable MIMO antenna for LTE and early 5G applications

In this work, a frequency reconfigurable MIMO antenna for 4G and early 5G applications is presented. The MIMO antenna design consists an array of two radiating/receiving elements positioned diagonally opposite to each other for better isolation (>12 dB) and pattern diversity. Each antenna element in MIMO array has a single module consisting two meandered radiating arms which could be connected or disconnected to the 50 Ω feedline electronically using two PIN diodes to operate in two switchable frequency bands/modes, 2.4 GHz or 3.5 GHz assigned for 4G/LTE and early 5G/Sub-6 GHz wireless communication technologies, respectively. The length of each radiating arm is around half-wavelength at operating frequency of interest (2.4 GHz or 3.5 GHz). The overall size of the MIMO antenna system is 120 mm × 60 mm × 1.52 mm. The proposed MIMO antenna configuration provides a 28.81% FBW (2.0 GHz to 2.7 GHz) and 49.7% FBW (2.57 GHz to 4.27 GHz) in both the resonance modes, respectively. The measured antenna gain values in two switchable frequency modes are 3.7 dBi and 4.2 dBi, respectively with overall efficiency > 60%. A low envelope correlation coefficient (0.0056 at 2.4 GHz and 0.0009 at 3.5 GHz) is achieved. Furthermore, the SAR and hand mode analysis is carried out to verify the performance of the MIMO antenna for mobile handset. The measured ergodic channel capacity of the MIMO antenna has been achieved more than 10b/s/Hz for both the mode.

Designing Hand-Immune Handset Antennas With Adaptive Excitation and Characteristic Modes

This article presents a design process for a hand-immune mobile antenna system. Characteristic modes (CMs) of a mobile phone and hand combination are analyzed to find the desired modes with good radiation properties. The efficient excitation of these modes is implemented by utilizing the antenna cluster technique. The proposed mobile antenna design has a small ground clearance of only 2 mm and can cover the 700-960 MHz low band, 1700-2700 MHz middle-high band (MHB) with two multiple-input-multiple-output (MIMO) antennas, and the 3300-3800 MHz high band with four MIMO antennas. The measurement results confirm that the proposed CM analysis-based design method in a realistic use case leads to a robust antenna design with competitive performance.

Reducing Hand Effect on Mobile Handset Antennas by Shaping Radiation Patterns

User interaction can significantly degrade handset antenna performances through frequency detuning and absorption. In this article, the relationships between the hand effects and the radiation patterns of the antennas are investigated using characteristic mode theory. First, we calculate the characteristic far fields of a typical monopole-loaded handset antenna with metal frames. Afterward, the radiation patterns of the handset antenna are simulated and obtained in two different scenarios, i.e., in free space and with hand. Then we map the antenna patterns in two scenarios to the characteristic mode patterns by calculating the weighting coefficients, which stand for the power contributions of the modes. By inspecting the variations of the weighting coefficients in free space and with hands, it is found that the modes with less radiation at the boresight and the backward directions are more robust to the hands. Accordingly, a handset antenna with little radiating power toward the boresight is designed. Compared to the reference antenna with the same feeding location, the efficiencies of the proposed antenna have been improved by 4.1 and 6.3 dB, respectively, for the left-hand and right-hand scenarios. Experiments have been carried out for the hand effects, with the measured results agreeing reasonably with the simulated ones.

Test Reduction for Power Density Emitted by Handset mmWave Antenna Arrays

The exposure to electromagnetic field (EMF) from phased antenna arrays integrated into wireless devices operating at the millimeter-wave (mmWave) part of the spectrum should be evaluated in terms of power density (PD). Two aspects related to test reduction when evaluating the radiation from handset antenna arrays are considered. First, the peak PD decay with the distance from 4-elements antenna arrays is analyzed. The focus is on finding the size of the volume around the handset beyond which the PD is so low that its measurement can be omitted. By limiting the measurements to the inside of the exposed volume, the total test time is reduced. Antenna configurations that are representative for current trends in handset technology are chosen: arrays of half-wavelength dipoles and patches operating at 26 GHz, 28 GHz, and 39 GHz, and having inter-element spacing either $0.5\lambda $ or $0.9\lambda $ . The second investigation aims to determine the critical distance between two 4-elements phased arrays for which the peak PD when the two arrays operate simultaneously is similar to the peak PD when only one array operates at the time. The study shows the configurations for which the number of tests can be reduced while having sufficiently accurate results.

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.