Search

In this article, the effect of an isolator in a multiple‐input multiple‐output (MIMO) antenna is analyzed in terms of its efficiency and isolation. An isolator is frequently utilized in MIMO antennas; however, the use of an isolator can aggravate the bandwidth or efficiency performance even though its isolation performance is improved. To develop a way of applying an isolator without sacrificing the bandwidth or efficiency performance, it is important to note that the characteristic modes excited by the MIMO antenna are related to the performance of the isolator. Two MIMO antenna systems using different ground characteristic modes are implemented to analyze the effect of the isolator. Via the isolator, both MIMO antennas achieved improved isolation, but the reference antenna underwent severe bandwidth degradation and efficiency degradation (from 31.81% to 16.69%), whereas the proposed antenna had relatively smaller reductions in bandwidth and efficiency (from 53.14% to 46.87%). [ABSTRACT FROM AUTHOR]

This letter presents a wideband compact dual-polarized antenna with endfire radiation pattern for the fifth-generation millimeter-wave (mm-wave) applications. The antenna achieves a –10 dB S11 bandwidth of 16.5% (25–29.5 GHz). The antenna has a thickness of 1.6 mm and a clearance of 3.4 mm. The presented four-element array achieves a maximum realized gain of 9.9 and 9.1 dBi for horizontal mode (H-mode) and vertical mode (V-mode), respectively. The antenna has a wide beamwidth in both elevation and azimuth planes with good scanning performance for both H-mode and V-mode. [ABSTRACT FROM AUTHOR]

A novel wideband millimeter (mm)‐wave antenna integrated with a multi‐input multi‐output (MIMO) antenna is presented for fifth‐generation (5G) applications. The proposed model consists of a 2 × 1 array‐based single‐element wideband antenna for mm‐wave applications, and a 2‐element strip‐based MIMO antenna system for sub‐6‐GHz band applications. In the ground plane, two clearance regions were etched to improve the impedance matching of MIMO elements while an open‐circuit rectangular tuning stub is attached to the mm‐wave antenna feed line to broaden its impedance bandwidth. The dimensions of the used panel are 100 × 60 × 0.8 mm3, which are among the typical dimensions used in mobile terminals. The mm wave antenna covers the frequency ranges from 25.08 to 28.08 GHz, while the frequencies from 2.88 to 4.58 GHz and from 5.15 to 6.15 GHz are covered by the MIMO antenna. Depending on the experimental results achieved, the suggested design might be considered a successful candidate for 5G applications, with wideband characteristics, excellent field correlation, and high gain functionality. [ABSTRACT FROM AUTHOR]

In this article, a miniaturized wide‐band and dual‐band loop‐type ground radiation antenna for mobile devices is proposed. The antenna feed structure, which consists of two shunt capacitors and a shunt inductor, enhances the bandwidth in both bands by generating an additional parallel feeding resonance in each band. Compared to the reference dual‐band loop‐type ground radiation antenna with a single loop feed that only uses a capacitor in series, the bandwidth of the proposed antenna is 1.6 and 2.13 times wider in the low and high bands, respectively under a 3:1 voltage standing wave ratio. The measured results indicate that the proposed antenna provides good radiation performance. [ABSTRACT FROM AUTHOR]

In this article, a wideband loop‐type ground radiation antenna is proposed for USB dongle applications. Wide bandwidth has been achieved using the orientation of the antenna embedded in the ground plane along with the impedance level of the feed structure. The ground clearance of the antenna is utilized so that the ground mode is tuned to the mid‐band frequency. The impedance level is controlled by using a series combination of a lumped inductor and a capacitor in the feed loop of the antenna. A good agreement between measured and simulated results has been observed. The measured bandwidth and peak total efficiency of the antenna are 1180 MHz and 88.27%, respectively. [ABSTRACT FROM AUTHOR]

In this study, we introduce a dual-band ground radiation antenna using an endless metal-rim mode control method that operates in the WLAN band. In the proposed antenna, the metal-rim modes are excited as one- and two-wavelength-mode radiators by a dual-band ground radiation antenna, which occupies a small space on the ground plane. The metal rim surrounds the ground plane with a gap of only 2 mm. In addition, two capacitors are inserted between the ground plane and the endless metal rim to control the one- and two-wavelength modes of the endless metal rim. Based on simulation and measurement results, we noted that the proposed antenna has an impressively high radiation performance. [ABSTRACT FROM AUTHOR]

A compact beam-steerable antenna array is proposed for 28 GHz mobile terminals. The proposed array consists of one active element and two passive parasitic elements. Two switches are utilized in the design instead of phase shifters. Each parasitic element can be terminated with short-circuited transmission lines of different lengths via one switch. By controlling the two switches, different reactive impedance is loaded on two parasitic elements. The radiation pattern of the active element can be scattered into different directions by two parasitic elements. The switching loss is studied, where two switches with 2.8 dB loss cause less than 1.82 dB loss for the whole array. The small array locations on the chassis are also investigated. The designed array is smaller than 0.81 wavelength, and covers the band of 28–29 GHz with the scan angle ≥±90°. By placing two arrays on each long chassis edge, 360° beam steering can be realized. Surface currents on the chassis are efficiently excited to achieve high gain with the small array. Measurements are carried out and align well with simulations. In practical applications, several small arrays can be implemented on the metal back cover and around a cellphone to combat users’ mobility. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we present a novel narrow-frame antenna with a size of 75 × 8 × 5.8 mm3 for 5.7 in. mobile phones. The antenna mainly consists of a monopole with four branches that are coupled to a two-branch grounded strip. Our antenna is able to cover more bands than other narrow-frame antennas by excitation of several resonant modes. The improved range of the antenna covers the following eleven bands: LTE700, GSM850, GSM900, DCS, PCS, UMTS, LTE2300, LTE2500, LTE3400 (3400–3800 MHz)/WiMAX3.5 GHz (3400–3650 MHz), WLAN5.2 GHz (5150–5350 MHz) and WLAN5.8 GHz (5725–5875 MHz). Another advantage of the proposed antenna is that it does not need any lumped element to match the antenna. The working principles of the proposed antenna are thoroughly studied. A prototype of the proposed antenna is fabricated and measured, with the results in good agreement with the simulation results. [ABSTRACT FROM AUTHOR]

Abstract: This letter presents an orthogonal mode 4‐antenna system operating in the 3.5‐GHz band (3.3–3.6 GHz) for the fifth‐generation (5G) multiple‐input multiple‐output (MIMO) mobile device. The 4‐antenna system is composed of 2 identical tightly arranged antenna pairs, and each pair is formed with an arrow‐shaped monopole and a bended dipole with gap‐coupled feeding. The tightly‐arranged antenna pair is face‐to‐face arranged on the front and back side of the substrate and the distance between the center of the 2 elements is only 1 mm; however, they have good isolation (better than 10 dB) and diversity performance (envelope correlation coefficient better than 0.11) with the help of orthogonal mode. This configuration provides promising solution for compactness of the MIMO antenna in mobile phone. The prototype was fabricated and measured, and the measured results show good agreements with the simulated ones. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a ground radiation antenna that uses controlled endless metal rim modes. In the proposed technique, the metal rim mode is tuned and excited as a one‐wavelength radiator by a small ground radiation antenna. The proposed antenna occupies a clearance of 1 mm × 4 mm in a 30 mm × 20 mm ground plane. A metal rim with dimensions of 34 mm × 24 mm surrounds the ground plane, and the metal rim is separated from the ground plane by a gap of 2 mm. In addition, a lumped capacitor is inserted between the metal rim and the ground plane to control the characteristic mode of the metal rim such that the resonance of the metal rim is tuned to be equal to the operating frequency. By performing simulations and measurements, we compare the performance of the proposed antenna with that of a reference antenna that does not have an inserted capacitor between the metal rim and the ground plane. The results show that a significant improvement of the radiation performance is obtained by employing the proposed technique. [ABSTRACT FROM AUTHOR]

The need for on-line information in any environment has led to the development of mobile satellite communication terminals. These high data-rate terminals require inertial antenna pointing error tolerance within fractions of a degree. However, the base motion of the antenna platform in mobile applications complicates this pointing problem and must be accounted for. Gimbaled motorised pedestals are used to eliminate the effect of disturbance and maintain uninterrupted communication. In this paper, a three-axis ship-mounted antenna on a pedestal gimbal system is studied. Based on the derived dynamic model of the antenna pedestal multi input-multi output PID andH∞linear controllers are designed to stabilise the antenna to keep its orientation unaltered towards the satellite while the sea waves disturb the antenna. Simulation results are presented to show the stabilisation performance of the system with the synthesised controllers. It is shown through performance comparison and analysis that the proposedH∞control structure is preferable over PID controlled system in terms of system stability and the disturbance rejection. [ABSTRACT FROM PUBLISHER]

A compact slot multiple-input multiple-output Antenna (CSMA) for smartphones with metal housing is proposed in this paper. The antenna has a slot radiator shared between two input ports and a T-shaped defect-ground slot (DGS) for decoupling. A function for selecting the best dimensions of the DGS for optimum decoupling is derived using the transmission theory. The CSMA antenna is designed using simulation to operate in the 2.4-GHz wireless-area-network (WLAN) system and then fabricated for measurement. Measured results show that the antenna has an impedance bandwidth (IMBW) of 2.4–2.48 GHz, mutual coupling from −19 to −29 dB and envelope-correlation coefficient (ECC) below 0.0867 within the IMBW. The antenna is very easy to fabricate and is a potential candidate for the MIMO smartphones antennas with metal housing. [ABSTRACT FROM PUBLISHER]

This communication presents a planar ultra-wideband multi-input multi-output antenna with pattern diversity and isolation improvement based on the theory of characteristic modes. The proposed antenna (for new-generation wireless mobile terminals) consists of two ultra-wideband antenna elements—a compact quarter loop and a circular planar monopole located on the opposite edges of a rectangular ground plane. These two antenna elements are able to excite different modes in the ground plane and thus realize the desired diverse radiation patterns and high isolation without any additional decoupling structures. The experimental results show that both antenna elements are ultra-wideband with impedance bandwidths (return losses more than 6 dB for the quarter-loop antenna and more than 10 dB for the circular planar monopole antenna) of 130% (2–9.5 GHz). The isolation is over 20 dB with a peak value of 50 dB. The realized gains are above 1.5 dBi. The total efficiencies are above 70%. The envelope correlation coefficient is less than 0.03 assuming that the antenna operates in an isotropic channel. [ABSTRACT FROM AUTHOR]

A wideband planar double-segmented loop antenna that can excite different modes with perpendicular polarized omnidirectional radiation patterns is designed for mobile platforms. The proposed antenna combines these resonant modes with adjacent resonant frequencies for wideband application. One of the modes is induced by the loop element itself and generates horizontally polarized radiation pattern. Meanwhile, the other mode generates vertically polarized radiation pattern when the ground plane is excited by the loop element and operates as a radiator. The measured results confirm that the antenna is capable of achieving wide bandwidth (10-dB return loss) from 2.1 to 2.9 GHz (the corresponding fractional bandwidth is 32%). The average total realized gain of the antenna is 2.75 dBi over the entire operating bandwidth. [ABSTRACT FROM PUBLISHER]

ABSTRACT An estimation method for the total radiation power (TRP) and radiation pattern of mobile antennas embedded in mobile phones using a planar near-field scanning method is proposed. The tangential magnetic fields on both front and rear faces of a mobile phone are measured both in magnitude and phase using a dual-probing technique in the time-domain. Moreover, for accurately obtaining the phase information from the measured data in the time-domain, a reliable triggering technique is introduced. The far-field is calculated by using the near-field to far-field transformation based on the equivalent principle and the image method. The calculated TRP and radiation pattern are validated by comparison with the measured TRP and radiation pattern in an authorized anechoic chamber, and good agreement has been achieved. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1437-1443, 2016 [ABSTRACT FROM AUTHOR]

An octa-band WWAN/LTE monopole antenna with a size of 80\,\textmm \times 8\,\textmm \times 5.8\,\textmm for 5.7-inch mobile phones is proposed and studied. The proposed antenna consists of a folded metal plate with a lumped-element high-pass matching circuit. The working mechanism is analyzed based on the S-parameters and the surface current distributions. The 0.25-wavelength, 0.5-wavelength, and 1-wavelength modes of the monopole antenna are excited and used. The attractive merit of the proposed antenna is that the height of the nonground portion is only 8 mm. A prototype is fabricated and measured. Its measured -6\;\textdB impedance bandwidths are 290 MHz (0.69–0.98 GHz) and 1.11 GHz (1.63–2.74 GHz) which cover the LTE700, GSM850, GSM900, GSM1800, GSM1900, UMTS, LTE2300, and LTE2500 bands. Within the two frequency bands, good radiation performances are obtained. [ABSTRACT FROM AUTHOR]

A worst-case estimate of an envelope correlation coefficient (ECC) is obtained for small multiple-input multiple-output (MIMO) mobile antennas operating below 1 GHz. The worst-case estimate is numerically derived in this paper using spherical and exponential wave functions. The derived result confirms that the worst-case ECC can be easily obtained from the rotation angle between the radiation patterns of two MIMO elements, which are attained directly from the amplitude of 2D electric field patterns without any additional phase and polarization information. As a practical example, MIMO mobile antennas with different antenna element arrangements are compared to verify the validity of the proposed worst-case estimate. Moreover, based on these analyses, we also suggest an effective approach to reduce the ECC of a small MIMO mobile antenna operating below 1 GHz by properly locating the antenna elements to make the radiation patterns perpendicular to each other. [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, an efficiency enhancement technique is proposed for a loop type ground radiation antenna on a small sized ground plane whose resonance frequency of the fundamental ground mode is significantly higher than the operating frequency. The efficiency is enhanced by matching the resonance frequency of the ground mode with the operating frequency. This was accomplished with a structure consisting of a loop of wire and inductors installed at both edges of the rectangular ground plane. The total length of each fabricated wire is 80 mm, which can be easily accommodated in the rim of a mobile device. The technique also increased the operating bandwidth. The measured efficiency of the antenna using the proposed technique is 47.44% and the bandwidth is 74 MHz at the Z-wave band. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:476-478, 2017 [ABSTRACT FROM AUTHOR]

Multi-antenna design in compact mobile handsets at frequency bands below 1 GHz is very challenging, since severe mutual coupling is commonly induced by simultaneous excitation of the chassis' fundamental dipole mode by more than one antenna element. To address this problem, a novel multi-antenna design approach is proposed herein to obtain efficient and uncorrelated antennas. By manipulating the chassis structure, more than one characteristic mode is enabled to resonate at frequencies below 1 GHz. With proper excitations for different characteristic modes, which are orthogonal to each other, well matched multi-antennas with low coupling and correlation are achieved. A chassis loaded with two T-shaped metal strips above its longer edges is taken as an example modification to illustrate the effectiveness of the proposed design approach at 900 MHz. This modification creates a new characteristic mode which resonates near 900 MHz. Afterward, two antenna feeds were designed to efficiently excite the chassis' fundamental dipole mode and the T-strip mode with very low correlation. The T-strip antenna covers LTE Band 8 (880–960 MHz), and the dipole mode antenna covers both LTE Band 5 (824–894 MHz) and LTE Band 8. The proposed dual-antenna design was found to outperform a reference design significantly, both with and without user interactions (i.e., one-hand and two-hand data grips). Practical aspects of mobile handset antennas are also investigated. The prototype was also fabricated and measured, and the measured results show reasonable agreements with the simulated results. [ABSTRACT FROM PUBLISHER]

ABSTRACT A very compact multiband internal antenna for handsets and tablets is presented. The proposed antenna is targeted to cover popular noncellular applications including GNSS, WiFi (IEEE 802.11a/b/g), and WiMax (Bands 3A/4/5). This work examines a new ceramic material suitable for the internal antenna design which gives a shorter guided wavelength and multiple resonances to achieve antenna size reduction, sufficient space utilization, and bandwidth increase. The occupied volume of the antenna radiator is only 12 × 4 × 3 mm3, approximately equal to 0.06λm × 0.02λm × 0.016λm (λm is the longest wavelength of the applications) so the antenna can be placed in the device flexibly. The proposed antenna should be the smallest antenna covering GNSS-WiFi-WiMax ever reported. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:169-175, 2014 [ABSTRACT FROM AUTHOR]

This paper presents a new configuration of a dual frequency, single feed, planar inverted-F antenna, which is suitable for implementation in different handsets. A parametric study, using finite element simulation software, high frequency structure simulator, has been carried out on each of the frequencies of this antenna and closed formulas in terms of antenna parameters have been obtained, which makes the designing process much easier. The proposed antenna has been fabricated according to the obtained formulas. Both, numerical simulation and experimental data are presented. [ABSTRACT FROM AUTHOR]

A compensation method for reducing the irradiation of the head of a cellular phone user without degradation of the far field is analyzed. This method uses two radiators that are located in the near region of each other, and create a weak field area in this region. The impacts of the mutual coupling between closely located radiators on the input impedance, current distribution, and fields of the radiators are studied. It is shown that the structure of two closely spaced monopoles is equivalent to the superposition of two basic structures: a two-wire open-ended line, and a single monopole. The shape and dimensions of the dark spots and the irradiation-reduction factor are determined. To facilitate the field calculations in the near zone of the antennas, a method based on replacing a piecewise-homogenous medium by an equivalent homogenous medium is used. The calculations and the experimental results in the presence of the head qualitatively agreed. [ABSTRACT FROM AUTHOR]

A compact multiband antenna for handset and tablet applications is presented, covering most LTE Bands (698–960 and 1710–2690 MHz). This study utilizes a new ceramic material suitable for the internal antenna design which gives a shorter guided wavelength and wider bandwidth for each resonant mode to achieve antenna size reduction, sufficient space utilization, and very low correlation coefficient as MIMO antennas. The occupied volume of the antenna radiator is only 35\,\times\,11\,\times\,5 mm^3, equal to 0.082\lambdam\times 0.026\lambdam\times 0.012\lambdam (\lambdam is the wavelength at 700 MHz) whose radiation aperture is only \lambdam/11 so the antenna is a good candidate as an internal antenna. [ABSTRACT FROM PUBLISHER]

A fold monopole/dipole/loop antenna offers unique advantages over a conventional Planar Inverted-F Antenna (PIFA) and monopole antenna for a mobile cellular device. Perhaps the most significant benefit is the fact that up to three resonant modes could be generated in a single continuous loop structure. In this paper, a novel hexa-band internal folded monopole/dipole/loop antenna has been proposed. The proposed antenna has four resonances in which three of them are 0.5\lambda, 1\lambda and 1.5\lambda modes. The distinctive feature of the antenna is an extra 2\lambda folded dipole mode, which has not been reported so far, is excited and utilized. All these four modes can be employed to cover the Low LTE700/GSM850/900 Band (LB: 698–960 MHz) and the High GSM1850/1900/UMTS2100 Band (HB: 1710–2170 MHz). The proposed loop antenna has been simulated, prototyped and tested. It is shown that the numerically simulated results are in close agreement with the experimental prototype results and proved that the antenna operates as proposed. [ABSTRACT FROM PUBLISHER]

In this paper, the triband mobile antenna system for broadband multimedia service in the Ka/K band and direct-broadcast-satellite service in the Ku band is proposed. The proposed antenna has a modified hybrid antenna (HA) structure with a Cassegrain reflector system with feeder for the K/Ka band, and a microstrip array for Ku-band service is composed of four linear subarrays and stacked on the subreflector of the HA. The main purpose of the proposed HA is to realize a high-gain mobile satellite antenna system with rapid 2-D beam scanning ability at low cost. Therefore, we proposed a novel beam-steering method through a subreflector that is rotational and flat. The feeder is composed of 20 dual-band and dual polarized horn elements in a hexagonal structure with an oval-shaped rim to maximize the efficiency of the HA. For system size reduction, small-sized active channel blocks composed of four channels were developed for signal amplification and main beam control, and the active channels for the transmitter and the receiver are connected with the horn elements of the feeder, respectively. In addition, the triplexers were very helpful for structurally simplifying the HA. A fabricated HA was successfully tested in a Korean satellite communications environment with motion simulator that can replace motor vehicles, and all radiation patterns in a beam-steering angle meet the international regulation of the International Telecommunication Union Radiocommunication Sector S.465-5. [ABSTRACT FROM PUBLISHER]

A multilayer thin film antenna for mobile devices is proposed. The proposed antenna consists of a (indium–zinc–tin oxide) IZTO/Ag/IZTO multilayer film, which is fabricated on a polyimide substrate (εr = 3.5) and a copper layer. The centre frequency of the antenna is 1260 MHz. The geometry of the antenna is made up of a coupled loop and two branches. The proposed antenna was fabricated using the DC pulse sputter instrument. The measured and simulated results of the antenna are given. The measured peak gain of the proposed antenna is 1.66 dBi. The transparency of the IZTO/Ag/IZTO thin film on the polyimide substrate is 86%. The advantages of the proposed antenna are high transparency, low resistivity and flexibility. [ABSTRACT FROM AUTHOR]