Gain Improvement Of Antenna Research Articles

Gain enhancement of microstrip antenna with a novel DNG material

AbstractIn this study, a novel double‐negative compact metamaterial (MM) that can operate in Ku‐band (12 GHz) is designed and fabricated. It is shown that the proposed structure can be used as a MM for a wide bandwidth of 6 GHz. A double electromagnetic lens layer is then formed using this MM unit cell in an array. Afterwards, obtained lens layers are used together with a conventional microstrip patch antenna (CMPA) operating at 12 GHz. The effect of the MM on the antenna gain and directivity is examined. The CMPA and MMs are fabricated, and measurements are performed in Akdeniz University Microwave Laboratory and simulated with Microwave Studio by Computer Simulation Technology. 71% and 50% improvement in antenna gain and directivity are obtained by using it as a double MM lens layer.

Dual-Band, Dual-Sense Textile Antenna With AMC Backing for Localization Using GPS and WBAN/WLAN

A wearable textile antenna with dual-band and dual-sense characteristics is presented in this work. It operates at the 2.45 GHz band for WBAN and WLAN applications, and at the 1.575 GHz band for Global Positioning System (GPS) applications. An antenna backing based on an artificial magnetic conductor (AMC) plane operating at 2.45 GHz band is introduced to reduce the backward radiation and to improve antenna gain. It consists of a $3\times 3$ array of square patch unit cells, where each unit cell is integrated with four square slits and a square ring. A square-shaped patch is then located on top of the substrate as its radiator. To enable dual-band operation, two corners of this radiator are truncated, with each of the four corners incorporated with a rectangular slit to enable its circular polarization characteristic in the GPS band. Simulation and experimental results are in good agreement and indicate proper antenna operation with linear polarization in the 2.45 GHz band and circular polarization in the 1.575 GHz band, with realized gain of 1.94 dBi and 1.98 dBic, respectively.

Circular Polarization Bandwidth Reconfigurable High Gain Planar Plasma Helical Antenna

A wideband circularly polarized (CP) multi-turns plasma helical antenna (HA) with reconfigurable bandwidth is investigated for wireless communications in the $x$ -band. The proposed plasma-based HA is suitable for integration with electronic circuit components used in system-on-chip applications. A parametric study on the effect of different design parameters on the antenna radiation characteristics is introduced. The antenna dimensions are optimized for wideband CP endfire radiation. The proposed antenna has an impedance matching bandwidth of 48%, a maximum gain of 8.5 dBi, and a wideband CP of 31%. The variation in the number of helix turns improves the antenna gain and bandwidth by changing the plasma frequency. An improvement in antenna gain and radiation efficiency is achieved by loading the antenna with shaped dielectric lenses with a different cross section. The endfire directional gain is improved to 11.5 dBi for hemispherical-shaped lens and 10.5 dBi for a quarter spherical lens with half-power beamwidth (HPBW) of 40°. The finite integration technique (FIT) is used to simulate and analyze the proposed structures.

Linear array of dual‐polarised slot‐coupled dielectric‐rod elements for wireless applications

The design of a dual-polarised series-fed microstrip array antenna for wireless applications, especially in the 5150–5750 MHz band, is delineated in this study, which consists of 12 dielectric rods, fed by circular slots. The rod height can be exploited to improve antenna gain and control its azimuth beamwidth. Using circular slot elements with a central crossing point improves port isolation and cross polarisation. The array elements are fed via two series-fed six-element arms having 25 dB Taylor distribution in each polarisation. The given arms are fed from the centre. Regarding H-polarisation, the arms are fed with a 180° phase shift to improve isolation between the ports as well as the cross polarisation. Additionally, a reflector plane is placed behind the array to suppress back-lobe radiation. A prototype of the array antenna is fabricated and measured. The return loss of the antenna is over 10 dB, varying from 5.1 to 5.8 GHz, and the isolation exceeds 30 dB over the bandwidth. The measured and simulated patterns are presented for both polarisations.

Control and improvement of antenna gain by using multilayer non-uniform metasurfaces

In this paper, a new high-gain antenna with beam control based on multilayer non-uniform metasurfaces (MNMSs) is proposed. The MNMS consists of multilayer non-uniform square and ring metal patches array. The phase-shift of the MNMS element can achieve 310° with the variation of geometrical sizes. Moreover, four high-gain antennas based on MNMS element are designed, fabricated, and measured to realize 0°, 30°, 45°, and 60° beam control in pitching plane, respectively. Relative bandwidth of the proposed high-gain antenna is above 12%. The simulated and measured results of the proposed antennas show that the wide-angle and azimuth direction beam control capability can be effectively realized by integrating different MNMS with the feeding horn antenna.

Application of a Compact Electromagnetic Bandgap Array in a Phone Case for Suppression of Mobile Phone Radiation Exposure

In this paper, a mobile phone case incorporating electromagnetic bandgap (EBG) material is studied to intercept electromagnetic (EM) waves from the phone and reduce the specific absorption rate (SAR). A loop antenna for the personal communications service 1900-MHz band is considered. In addition, three different mobile phone cases associating EBG structures with optimized positions are used to improve SAR reduction. Furthermore, antenna performance with an EBG structure is investigated with a full-body EM simulation program, SEMCAD X, and an individual performance analysis of each EBG structure was carried out by using Ansoft HFSS. A human head phantom to replicate the specific anthropomorphic mannequin model was used for measurements. From simulation and measurement, it is found that placing an EBG structure in a phone case can improve antenna gain and reduce SAR. Moreover, a maximum gain increment of 19% and an SAR reduction of 24% were found. This paper reveals the future applications of EBG structures for SAR reduction in mobile phones.

A Compact and Low-Profile MIMO Antenna Using a Miniature Circular High-Impedance Surface for Wearable Applications

A new miniature circular high-impedance surface (HIS) is used to design a compact and low-profile multi-in multi-out (MIMO) antenna for wearable applications. The antenna is designed to operate from 2.4 to 2.49 GHz for wireless local area network application. By employing a pair of degenerated characteristic modes of a circular loop antenna, the MIMO antenna can achieve a good port-to-port isolation (>15 dB) without increasing its geometric size. A four-element HIS is chosen to match the antenna profile, and a 2 dBi antenna gain improvement is observed. The design was optimized considering the effect of packaging and then a prototype with the optimal parameters was fabricated and tested. Measurement results are in good agreement with simulation results. Furthermore, the loading effect due to lossy human tissue is also considered and the results show that the antenna has a robust performance against the human phantom and a low specific absorption rate can also be obtained.

Antenna gain enhancement by using metamaterial radome at THz band with reconfigurable characteristics based on graphene load

The reconfigurable concept of a graphene loaded patch antenna with increasing gain is proposed in this paper. We have developed the patch antenna with inset feed for THz band application for which graphene load is used to obtain the reconfigurable characteristic. It has been shown that by increasing the graphene chemical potential, the antenna resonant frequency shifted and the gain increased drastically up to 4 dBi. Additionally, we have shown that antenna efficiency is improved up to 78% which shows more than 100% of enhancement in comparison to basic antenna by increasing the graphene chemical potential. Finally, considering the antenna gain improvement, we have implemented the metamaterial layer over the antenna. In this case, the gain is increased more than 5–6 dBi. In addition, when we put the metamaterial layer over the antenna, the graphene layer shows more linear characteristics. By using parametric studies, we have defined the best point for metamaterial layer around 0.58λ. The final antenna gain is more than 11 dBi, which is useful for THz communication and THz medical imaging systems.

Design of Ultra-Wideband Tapered Slot Antenna by Using Binomial Transformer with Corrugation

Abstract In this paper, the tapered slot antenna (TSA) with corrugation is proposed for UWB applications. The multi-section binomial transformer is used to design taper profile of the proposed TSA that does not involve using time consuming optimization. A step-by-step procedure for synthesis of the step impedance values related with step slot widths of taper profile is presented. The smooth taper can be achieved by fitting the smoothing curve to the entire step slot. The design of TSA based on this method yields results with a quite flat gain and wide impedance bandwidth covering UWB spectrum from 3.1 GHz to 10.6 GHz. To further improve the radiation characteristics, the corrugation is added on the both edges of the proposed TSA. The effects of different corrugation shapes on the improvement of antenna gain and front-to-back ratio (F-to-B ratio) are investigated. To demonstrate the validity of the design, the prototypes of TSA without and with corrugation are fabricated and measured. The results show good agreement between simulation and measurement.

Exponential Antipodal Vivaldi Antenna With Exponential Dielectric Lens

The expansion of wireless technologies poses various requirements such as stable radiation characteristics in a wide frequency range. This letter presents an exponential antipodal Vivaldi antenna with a dielectric lens replacing part of the substrate in antenna aperture, with dimensions of 76 × 130 mm2. The shape of the lens also follows exponential structure in its inner (where lens meets the antenna substrate) and outer edges. Using a dielectric with higher constant in the proposed antenna provides 1 dB improvement in antenna gain and 24% of 3-dB beamwidth reduction.

Design of a 60-GHz Quasi-Yagi Antenna With Novel Ladder-Like Directors for Gain and Bandwidth Enhancements

In this letter, the novel ladder-like directors are proposed and investigated for antenna gain and bandwidth enhancement. First, single-stage director is introduced to the quasi-Yagi antenna design to improve directivity in the endfire direction. Then, to further enhance the performance, multistages of directors form ladder-like structures that are co-designed with the antenna, with careful considerations of mutual coupling effects. To validate the concept, a 60-GHz antenna using proposed directors is designed and fabricated. The simulation results reveal an antenna gain improvement of 2.2–3.4 dB and bandwidth improvement of 30% by using the proposed directors. The measured antenna achieves a gain of 11.7 dB at 60 GHz and in-band cross polarization of less than $-$ 15 dB. The antenna occupies a compact size of $9.2 \times 10~\hbox{mm}^2$ .

A Compact Wideband Dielectric Resonator Antenna With a Meandered Slot Ring and Cavity Backing

We design a compact cavity-backed antenna structure where a dielectric resonator (DR) element is surrounded by a meandered circular slot ring to enhance radiation efficiency. The DR for the antenna is cylindrical in shape, and four degenerate HE 11δ modes are excited and driven by four, quadrature-fed aperture-coupled slots. Such a compact implementation hybridizes operation of the DR with the miniaturized ring as well as the four aperture-coupled slots for circular polarization. Measured realized gain values are greater than 5 dBic from 1.14 to 1.55 GHz defining a bandwidth of more than 30%. In addition, the half-power and 3-dB axial-ratio beamwidths were measured to be more than 100 ° and 200 °, respectively. The proposed design technique to employ such a secondary meandered slot ring may also be useful to improve antenna gain, bandwidth, and efficiency for other antenna and array structures.

Development of a Linearly Polarized Circular Substrate-Integrated Waveguide Cavity-Backed 2 × 2-Slot Antenna Array

This article presents two new cavity-backed slot antennas utilizing substrate-integrated waveguide technology and offering high gain. Radiation performances of the proposed antennas are experimentally and numerically evaluated. Using two slots backed by a circular cavity, one can improve antenna gain by 2 dB over the gain of a single-slot antenna. Then a 2 × 2-slot antenna array backed by two cavities is presented, which offers a gain of 9.2 dBi, which is 4.2 dB and 2.2 dB higher than the gain of single- and two-slot antennas, respectively. All the proposed antenna structures are made on a single-layer substrate, and a low-cost printed circuit board process is used for fabrication.

Improving the Efficiency of Transparent Antenna Using Gold Nano Layer Deposition

In this letter, a practical method to enhance the efficiency of a transparent antenna is presented. The proposed method which involves homogeneous and heterogeneous gold nanolayer deposition by dc sputtering does not have common limitations of transparent materials. By homogeneous deposition of the gold nanolayer, ohmic loss will decrease and gain will improve. The results confirm the effectiveness of the method and significant antenna gain improvement at different frequencies. In addition, by heterogeneous deposition method we have shown that transparency can improve. In this method, the gold nanolayers with various thicknesses are deposited on the locations where the current density is high. In this case, the antenna gain increases while the transparency is sustained. To assess the performance improvement, copper, ITO, homogeneous and heterogeneous deposited antennas have been compared. Final results and a methodology to select the optimum thickness and location for deposition are also presented.

Design of asymmetrically slotted hexagonal patch antenna for high-gain UWB applications

A compact slot antenna for high-gain ultra wideband applications is presented. The slot is asymmetrically cut in the ground plane and is a combination of two rectangles. A hexagonal patch with two stepped coplanar waveguide-feed is used to excite the slot. The capacitive reactance of the hexagonal patch is neutralized by the inductive reactance created by the asymmetric slot and results into wider impedance matching. The measured impedance bandwidth of the proposed antenna is 11.85 GHz (2.9–14.75 GHz). The radiation patterns of the proposed antenna are found to be omni-directional in the H-plane and bi-directional in the E-plane. To enhance the gain of the antenna, a compact three-layer frequency selective surface (FSS) is used as a reflector. The overall thickness of the FSS is 3.5 mm. There is 4–5 dBi improvement in antenna gain after application of the FSS. The measured and simulated results are in good agreement.

Design of Dual-Band Millimeter-Wave Antenna-in-Package Using Flip-Chip Assembly

A dual-band antenna-in-package for millimeter-wave (mmW) applications is presented in the paper. The proposed antenna, which consists of a radiating slot and an air-filled cavity, is fed by a microstrip loaded with two tuning open-circuited stubs through a coupling C-shape aperture to achieve dual-band characteristics. The air-filled cavity, which is formed by the space between CMOS chip and integrated passive device substrate after flip-chip assembly process, can reduce loss and improve antenna gain. Simulation and measurement regarding antenna reflection coefficient, radiation pattern, and peak gain are conducted for design validation. The measured results show that the antenna can operate in V-band and E-band, and the impedance bandwidths with the reflection coefficient less than -10 dB are 6.1% and 5.8%, respectively. The measured gains are -2 dBi at 58 GHz and 0.3 dBi at 77 GHz, respectively. The proposed antenna is well suited for dual-band mmW high-data-rate wireless communication systems.

Electrically Small Broadband VHF/UHF Planar Antenna Matched Using a Non‐Foster Circuit

ABSTRACTA broadband non‐Foster matched Planar Inverted‐F Antenna is proposed for 100–500 MHz VHF/UHF handheld terminal applications. The proposed design shows that in the lower frequencies antenna gain improvement of as much as 25 dB can be obtained with the help of the broadband matching circuit for a small antenna on a 0.05 wavelength ground plane at the lowest frequency. The issues of RF power versus matching and circuit stability are pointed out. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2494–2497, 2013

Miniature Hexaferrite Axial-Mode Helical Antenna for Unmanned Aerial Vehicle Applications

We demonstrated the size reduction of axial-mode helical antenna based on Co2Z hexaferrite-glass composite. Axial-mode helical antenna was employed to provide reliable communication for unmanned aerial vehicle (UAV) applications. The conventional axial-mode helical antenna uses an air core or low dielectric material, resulting in large antenna size. To increase the miniaturization factor n = (μrer)0.5, a Co2Z hexaferrite-glass composite was used as an antenna core. The 3-dimensional finite element method (FEM) simulation was performed to design a hexaferrite helical antenna and confirm the axial-mode operation at 2.44 GHz with gain of 2.0 dBi. The designed hexaferrite helical antenna showed 82% of volume reduction and good impedance matching compared to the air-core antenna. The axial-mode hexaferrite antenna was fabricated based on the designed structure and characterized in an anechoic chamber. The maximum gain of 0.541 dBi was measured with the pitch angle of 10° at 2.39 GHz. Also, a two-element axial-mode antenna array was designed based on the miniature hexaferrite antenna to further improve antenna gain. Maximum gain of 4.5 dBi at 2.43 GHz was simulated for the antenna array. Therefore, high gain and miniature antenna can be achieved with the combination Co2Z hexaferrite-glass composite and antenna design technology.

DOUBLE-LAYER RADIAL LINE HELICAL ARRAY ANTENNA WITH RECTANGULAR APERTURE

A double-layer radial line helical array antenna with rectangular aperture is proposed. With rectangular aperture, the antenna can be assembled to form high gain antennas. The use of double-layer feed system ensures an equal-amplitude in-phase feed for all elements in an expected frequency band, which can improve antenna gain and aperture e-ciency. This paper presents its design concept, derives pertinent design and performance, and a 16-element array antenna is simulated and measured. The experimental results show that in the range of 3.8GHz to 4.2GHz, the antenna gain is over 17.7dB, aperture e-ciency over 82%, antenna sidelobe level below i12:0dB, antenna axial ratio below 3.2dB, and antenna VSWR below 1.52.

A Novel Technique in Simplifying the Fabrication Process and Improving the Reflection Coefficient of the Linear Polarized Radial Line Slot Array (LP-RLSA) Antennas

A novel technique in simplifying the fabrication process of LP-RLSA antenna as well as improving the reflection coefficient of LP-RLSA antenna is proposed in this paper. This technique utilizes a FR4 board added on the top of the normal LP-RLSA antenna. Theoretically, FR4 dielectric material is able to reduce antenna reflection coefficient since it produces the signal that has a different phase with the propagating signal within the antenna cavity. Moreover, by utilizing the copper part of the FR4 board as the radiating element, the fabrication process can be simplified since the antenna slots can be cut utilizing the simple low cost etching process. In this paper, the theory about how the utilization of the FR4 board can improve the reflection coefficient response is explained. The parameters that influence the capability of FR4 board in improving the reflection coefficient response are also discussed. A LP-RLSA antenna with FR4 board and a LP-RLSA antenna without FR4 board are designed and simulated at frequency of 5.8 GHz. The simulation result shows that the thickness and permittivity values of FR4 board influence the reflection coefficient response and the antenna gain. The best values of the permittivity and thickness of the FR4 board are 4.3 and 1.6, respectively. The simulation result shows that these values can improve antenna gain up to 2.45 dB. They can also improve reflection coefficient response significantly from –3 dB to –25 dB. It is discovered that the LP-RLSA with FR4 board also produces the beamsquint effect from –10° up to 10° from the boresight direction. The prototype of the designed antennas is fabricated and measured. The measurement and simulation results show that the LP-RLSA with FR4 board has a better gain and better reflection coefficient than the LP-RLSA without FR4 board, thus prove the concept of the novel technique.