Front-to-back Ratio Research Articles

A high FBR low SAR and AMC-backed compact wearable antenna array for WBAN applications

Abstract In this paper, a wearable antenna array based on a 9 × 3 artificial magnetic conductor (AMC) array is proposed with the characteristics of compact, low profile, low specific absorption rate (SAR), high front-to-back ratio (FBR) and high gain for wireless body area network (WBAN) bands. The proposed wearable antenna consists of a four-element array and an AMC array. The size of antenna array loaded AMC is 137.7 × 45.9 mm2. The dielectric substrate of the antenna and the AMC structure are made of 0.1 mm liquid crystal polymer material, which is flexible and low profiled. The antenna operates from 5.62 to 6 GHz after the AMC structure is loaded. The gain increases by 3.23 dB, reaching 12.03 dB at 5.8 GHz. And the FBR value is raised by 26.04 dB. The highest SAR value of the simulated antenna on the human model is 0.0496 W/kg, far less than the US federal or EU requirements. After constructing and testing the antenna, the outcomes of the tests agreed with the results of the simulation. The flexible antenna array with AMC structure has good prospect in WBAN applications.

Modeling and Design of Improved‐Gain Wideband Magneto‐Electric Dipole Antenna for Micro‐BTS Applications

AbstractA wideband Magneto‐Electric Dipole (MED) antenna with high gain is proposed for the 700/800/850/900 MHz frequency bands for cellular network applications. The antenna comprises a half‐wavelength bow‐tie‐shaped dipole, an elongated magnetic loop and a ground reflector with four Elevated Ground Planes (EGPs) at reflector's corners. The EGPs enhance the antenna gain and Front‐to‐Back Ratio (FBR), which is a promising technique in the MED antenna design. The antenna is excited by a ‐shaped coupling element. An analytical model of the proposed antenna is developed by employing Schelkunoff's model for dipole antennas and the transmission line theory complemented by radiation resistance corrections. The antenna design is validated with full‐wave numerical simulations. The antenna is fabricated using cut and bent metallic plates and tested in an anechoic chamber. The analytical, numerical and experimental results are in a good agreement. The experimental results confirm that the proposed MED antenna with dimensions of achieves a bandwidth of 61.53% (623.1–1176.8 MHz) for and a stable gain of 9.8 1.9 dBi. By employing the EGPs, the realized peak gain and FBR are enhanced by 0.52 dBi and 1.1 dB, respectively.

Enhanced Antipodal Vivaldi Antenna with SSRR metamaterial for improved 5G performance in the 38 GHz band

This study involves the integration of a compact Antipodal Vivaldi Antenna (AVA) with a square-shaped split ring resonator (SSRR) metamaterial to achieve improved performance, specifically in the 38 GHz band of 5G applications. The compact antenna is fabricated on Roger's substrate 5880 with 20 x 6 x 0.5 mm3 dimensions. The operational frequency ranges from 34 GHz to 43.8 GHz, catering to the specific needs of the 5G spectrum. To optimize the antenna's performance, corrugations are strategically introduced in the flares of the AVA, resulting in a notable improvement in the front-to-back ratio (FBR) by 18.35 dB. Additionally, square-shaped split ring resonators (SSRRs) are integrated into the AVA aperture, contributing to a gain enhancement of 4.6 dBi. The overall design achieves a gain ranging from 9.2 dBi to 10.4 dBi across the 38 GHz frequency band. The proposed AVA demonstrates good characteristics, with the highest front-to-back (FBR) value recorded at 20.4 dB at 40.6 GHz. The FBR consistently exceeds 15.6 dB throughout the specified frequency range. The antenna design is fabricated, simulated, and experimentally verified, affirming its suitability for compact 5G devices. The results indicate that the proposed miniaturized AVA, incorporating SSRR metamaterial and optimized flare corrugations, is an efficient candidate for compact 5G devices, offering enhanced gain and FBR over the desired frequency band.

Ultra‐wide Band Antipodal Vivaldi Antenna Using Metasurface Lens for Gain and Front‐To‐Back Ratio (FBR) Improvement

AbstractThis paper addresses the limited gain of conventional Antipodal Vivaldi Antenna (AVA) at higher frequencies. We propose a novel Metamaterial Lens Vivaldi Antenna (MLVA) design that overcomes this limitation by integrating an exponentially tapered antenna lens and a strategically placed Near Zero Refractive Index (NRZI) metamaterial lattice. The MLVA achieves exceptional wideband performance with a −3 dB gain bandwidth exceeding 148.6% from 3.7 to 25 GHz. The result demonstrates a peak realized gain of 11.8 dBi at 11.2 GHz, compared to 9.1 dBi conventional AVA, especially beyond 5 GHz. The compact MLVA design measures only 120 × 78 × 1.524 mm3 (1.48 × 0.96 × 0.0188λ03) λ0 where free‐space wavelength is the lowest frequency and is fabricated on RO4350 B substrate with a 50‐Ω SMA connector. Key features of the design include exponential flaring, and trapezoidal lens geometries chosen for their inherent ability to effectively collimate and direct the spherical wavefront. The incorporation of a dielectric lens and metasurface further enhances gain and Front‐to‐Back Ratio (FBR) by directing the majority of energy in the end‐fire direction. Experimental results validate the effectiveness of the proposed design, confirming simulation predictions. These outstanding characteristics make the MLVA a promising candidate for diverse wireless communication and radar applications demanding high data rates across a broad frequency range.

CSRR and EBG loaded wideband THz dielectric resonator MIMO antenna for nano communication and bio-sensing applications

In this paper, a wideband Graphene-inspired dielectric resonator THz MIMO antenna is designed. The antenna has dimensions of 56 × 56 × 3.6 μm³ and is designed on a Rogers RO3035 substrate with a relative permittivity of 3.6 and loss tangent of 0.0015. This antenna works in the range of 6.0 THz-12.5 THz (70.76 %) with a peak gain of 7.68 dBi and radiation efficiency (>70 %) is suitable for use in medical imaging and THz wireless near-field applications. A CSRR is loaded to obtain band notch characteristic for avoiding interference between nearby wireless devices in the range of 10.6–10.8 THz. EBG was also introduced with a patch antenna to reduce surface wave loss and improve isolation, resulting in a high front-to-back ratio (FBR) in the range of 10–12.5 THz. Without the graphene disk, the silicon-based DRA did not achieve significant gain. At a chemical potential of 0.5 eV and a relaxation time of 0.1 ps, the proposed DRA demonstrated good antenna properties. By varying the chemical potential and relaxation time, frequency agility was easily achieved. A Graphene disk having a height of 3 μm is placed on a Silicon (εr = 11.1) based cylindrical DRA to provide high gain and improve the impedance bandwidth, achieving wide bandwidth from 6.0 THz to 12.5 THz. The proposed two element antenna performance is evaluated by parameters such as gain, return loss, isolation between two antenna elements, and diversity parameters like Envelope correlation coefficient ECC<0.1, Directive Gain >9.5 dB, Total Active reflection Coefficient >10 dB and Avg. Channel capacity loss <0.35bps/Hz so that the proposed antenna is suitable for wideband nano/optical communication in IoT-6G. Furthermore, the antenna is suitable for biological sensing applications due to its average sensitivity and FOM for hemoglobin and urine of 805.33GHz/RIU and 805.55GHz/RIU, respectively, and 3.37 and 10.55.

A miniaturized dual wide‐band polarization reconfigurable antenna integrated with artificial magnetic conductor for next‐generation wireless applications

SummaryIn today's intricate wireless communication environment, ensuring system quality demands the use of a reliable and versatile antenna system. This research article introduces a polarization reconfigurable antenna integrated with a 4 × 4 Artificial Magnetic Conductor (AMC) surface. The AMC unit cell exhibits a triple‐band reflection phase response at 1.8GHz, 4.5GHz, and 5.5GHz, demonstrating double negative metamaterial behavior. The antenna features two distinct C‐shaped metal strips connected to two PIN diodes, enabling dynamic current distribution adjustment. Consequently, the proposed antenna offers three reconfigurable states, facilitating seamless switching between dual circular polarization (left and right‐hand circular polarization) and linear polarization. With a frequency coverage ranging from 1.29 to 2.52GHz and 3.59 to 6.15GHz, the antenna boasts a maximum axial ratio (AR) bandwidth of 31.96%. Additionally, it achieves a maximum peak gain of 5.5 dB and maintains front‐to‐back ratio (FBR) values exceeding 25 dB, while recording a minimum specific absorption rate (SAR) value of 0.1059 W/kg. The integration of the AMC surface ensures enhanced performance of the antenna. Experimental results from constructed prototypes closely align with simulation outcomes, validating the effectiveness of the proposed antenna. Consequently, this antenna holds significant promise for next‐generation wireless applications.

Novel Design of a Bandwidth Enhanced and Frequency Reconfigurable, Wearable Antenna for Body Centric Communication

This paper proposes a novel design for a frequency reconfigurable and bandwidth-enhanced antenna for use in biomedical telemetry applications. Data pertaining to a patient’s body parameters, such as blood pressure, pulse, and temperature, are gathered using sensors and then transmitted to a remote place for monitoring. The proposed antenna is connected to a wearable transmitter, which transfers the body parameter data to a centrally located nearby control unit. The antenna operates in the 5.8 GHz band in single-band mode and in the 4.27 GHz (C band) and 5.8 GHz industrial, scientific, and medical (ISM) bands in dual-band mode. The use of ethylene-vinyl acetate foam as a substrate makes the structure waterproof and ultraviolet resistant. The basic antenna structure equipped with proximity coupling offers a front-to-back ratio (FBR) of 17.62 dB and a bandwidth of 122 MHz. With an additional upper patch and resonant slots, bandwidth enhancement of 82.85% and 11.57% improvement in the FBR are achieved, respectively. Overall, a maximum FBR of 19.66 dB and gain of 5.0 dBi are attained over the resonant frequency. The specific absorption rate is found to be 0.145 W/kg for 10 gram of tissue.

Modeling and performance enhancement of compact FSS based low‐profile broadband monopole antenna

SummaryIn this research work, a compact‐sized offset‐fed broadband monopole antenna is designed using a frequency selective surface (FSS) reflector to enhance gain, radiation efficiency, and FBR and validated experimentally. The designed antenna consists of a triple v‐slit on a rectangular‐shaped radiating patch, a modified partial ground, and a frequency‐selective surface (FSS). It exhibits a ‐10 dB impedance bandwidth of 9.37 GHz (6.55–15.92 GHz) and a fractional bandwidth of 83.4%, yielding significant portions of the C‐band (4–8 GHz), the X‐band (8 GHz–12 GHz), and covering a considerable part of the Ku‐band (12–18 GHz). The proposed prototype equivalent circuit model has been developed progressively to validate the electromagnetic simulation results. The measured peak gain is 14.25 dBi (6.8 dBi without FSS) at 14.2 GHz with an average radiation efficiency of ≥ 96% for the FSS integrated antenna. Furthermore, the proposed design improves the front‐to‐back ratio (FBR) by 15 dB throughout the broadband frequency range. The proposed antenna peak gain, reflection coefficient (S11), radiation efficiency, and radiation patterns show adequate similarity between the tested and simulated results and have numerous advantages, including very compact size, simple structure, minimum S11 (dB), high gain, and broadband capability.

Improvement in notch band characteristics of a hexagonal super wideband antenna by interfering back radiation out of phase with front radiation using frequency selective surface

SummaryA band‐notched super wideband (SWB) planar monopole antenna with improved notch characteristics is proposed in this article. A hexagonal SWB antenna operating in the frequency range from 3.04 to 36 GHz is initially designed on Arlon substrate. The hexagonal patch is then loaded with optimum sized U‐shaped slot to eliminate WLAN band (5.15–5.85 GHz). The notch band's characteristics are further improved by incorporating a frequency selective surface (FSS) of a square array at a specific distance below the antenna to introduce a phase delay of 180° between the back radiation reflected by the FSS with the front radiation at the notched frequency. Improvement of notch band gain, efficiency, and antenna front‐to‐back ratio (FBR) are studied. The antenna without embedding an FSS exhibits working spectrum from 3.1 to 33.6 GHz with notch frequency gain of −2.6 dBi and efficiency 53%. The inclusion of an FSS layer at 25.2 mm behind the antenna results in notch frequency gain of −7.6 dBi with an efficiency of 23%. FBR improvement of about 16 dB is achieved at 8 GHz, and FBR is reduced by about 5 dB at the notch frequency. 169% fractional bandwidth with bandwidth dimension ratio (BDR) of 1622 is achieved in this proposed FSS integrated antenna. The inclusion of FSS to improve the band elimination performance represents the novelty of this proposal. The data are validated by electromagnetic simulation and physical measurement techniques.

A wideband end‐fire stepped slot antenna with gain enhancement and filtering capability

AbstractA wideband end‐fire stepped slot antenna with gain enhancement and filtering capability is proposed. On one hand, a parasitic dipole serving as a director is introduced in the stepped slot to improve the radiation gain of the slot antenna without increasing its physical size. It is found that a gain enhancement of about 2 dB can be achieved after adopting such approach. On the other hand, an absorptive branch possessing a nearly complementary frequency response with regard to the one of the slot antenna is in‐parallel loaded at the microstrip feedline. It allows the partial dissipation of the out‐of‐band/non‐radiated RF‐signal power of the antenna to attain both an RF‐quasi‐absorptive behaviour and filtering capability. It is found that after loading the dissipative branch, the out‐of‐band radiation efficiency of the slot antenna is reduced to less than 20%. The measured results of a fabricated proof‐of‐concept antenna prototype show a reasonable agreement with the simulated ones and verify the RF performance merits of the proposed stepped slot antenna, such as wide RF operating band covering the 3.39−4.73‐GHz range, end‐fire radiation with a front‐to‐back ratio (FBR) above 10 dB, flat radiation gain, and co‐integrated filtering functionality with RF‐quasi‐absorptive capability.

Design and Implementation of Novel H-Shaped Self-Diplexing SIW Rectangular Cavity-Backed Antenna with Harmonic Suppression for Terrestrial Communications

A novel and low profile, planar, rectangular cavity-backed self-diplexing substrate integrated waveguide (SIW) antenna with H-shaped slot for dual-band wireless services was designed and demonstrated. The proposed antenna structure radiates from H-shaped slot, which is etched on top of the SIW rectangular cavity, and is excited by two separate 50 Ω microstrip feed lines. The H-shaped slot is a combination of two vertical slots and one horizontal slot; because of that the presented antenna radiates at two distinct frequency bands around 8.95 GHz and 10 GHz, simultaneously. The design methodology results show that the H-shaped slot is significantly more effective than various other slots in the proposed geometry to suppress the unwanted harmonics, attaining good impedance matching and bandwidths and achieving better isolation between these two ports. Hence, the complete design mechanism helped to achieve self-diplexing characteristics. Furthermore, a self-diplexing H-shaped SIW rectangular cavity-backed antenna was fabricated and characterized for the complete demonstration purpose and found good covenants between the simulated one. Measured results show that the presented designed has impedance bandwidths for the lower and upper frequency bands of around 2.0% (8.89–9.03 GHz) and 3.1% (10.01–10.32 GHz), respectively, and obtained maximum measured gain of 5.11 dBi and 5.41 dBi at 8.95 GHz and 10.15 GHz, respectively. The proposed self-diplexing SIW rectangular cavity-backed structure shows that front-to-back ratios (FTBRs) are more than 21 dB, and on the other side, it provides good isolation between the two ports, which is more than 20 dB.

Front‐to‐back ratio improvement of a compact base‐station antenna for 5G NR applications

AbstractThe front‐to‐back ratio (FBR) of a compact dual‐polarized antenna is improved for 5G new radio (NR) base‐station applications. A rim made of partially reflective surfaces is introduced to improve the FBR. A meta‐surface and a parasitic element are employed to lower the antenna height. The dual‐polarized base‐station antenna with improved FBR features a compact size of , where is the wavelength in free space at the lowest operating frequency. The FBR achieved over the 5G NR n28/n82/n83 bands (0.69–0.96 GHz) for return loss &gt;15 dB is higher than 26 dB. The antenna gain is higher than 7 dBi and the isolation is higher than 30 dB.

A Compact 1:3 Power Divider Incorporating 180° Shifted Path for Polarization Purity Enhanced Base Station Subarray

This paper presents a compact 1:3 power divider and a base station subarray antenna with enhanced polarization purity exhibiting high cross-polarization discrimination (XPD) and high input port isolation. The compact 1:3 power divider incorporating a 180° shifted path is proposed to achieve both polarization purity and the wideband characteristics of the subarray antenna, which is difficult to implement using the conventional dual-feed method in limited areas. Using the proposed power divider, a dual-polarized quadruple Π-probe feed stacked patch antenna array is designed, which achieves a wide bandwidth of over 30% (&lt; -13 dB) from 1.68 GHz to 2.25 GHz. The XPD is increased by approximately 8 dB and 5 dB at 1.71 GHz and 2.11 GHz, respectively, to attain an increase in the isolation bandwidth (&lt; -20 dB) from 14% to 43%. Furthermore, the measurement results of a 4 × 3 antenna array confirm the effectiveness of the proposed design in terms of XPD and isolation while maintaining the bandwidth and beam performance. This study demonstrates a relatively wide bandwidth between patch antennas, despite the use of multiple subarrays. The comparative results also show a relatively better frontto-back ratio and isolation of the proposed design.

Modal analysis and higher order mode suppression of a high impedance surface-based bowtie antenna

Abstract The present work studies the design of a high impedance surface (HIS)-based bowtie antenna in the framework of characteristic mode analysis (CMA) and proposes the method of higher order mode suppression. A triangular-elliptical bowtie antenna operating in the frequency range of 1.6–6 GHz is designed. The radiating and higher order modes of the proposed antenna are identified using CMA, and an HIS structure is used to enhance the desired mode and to suppress the higher order mode in order to get high gain, good front-to-back ratio (FBR), and stable radiation characteristics. The final designed HIS-based bowtie antenna gives stable radiation patterns from 1.7 to 5.5 GHz with a maximum boresight gain of 10.5 dB. Also, gain from 6.5 to 12 dB and FBR from 8 to 18 dB are obtained in the operating bandwidth. The proposed antenna features the advantages of low profile, wideband and high boresight gain making it suitable for ground-penetrating radar applications.

Dual-Wideband Antenna with Dual Polarization and Enhanced Front-to-Back Ratio for High-Speed Communication Applications

The proposed antenna introduces a dual-wideband, dual-polarization design, employing Y-shaped bowtie radiators strategically positioned on both sides of an FR-4 substrate. This configuration aims to achieve polarization diversity, a crucial aspect in enhancing the performance and efficiency of wireless networks. To achieve this, improvements were made in radiation characteristics, particularly the front-to-back ratio (FBR), through the incorporation of a ring reflector and director. This led to an impressive average FBR enhancement of 7.38 dB at the lower band (LB), and 4.94 dB at the upper band (UB), respectively. Furthermore, the reflector and director height in relation to the radiator was meticulously adjusted to achieve a low-profile structure of dimensions 0.340λ0 × 0.340λ0 × 0.126λ0 (at 0.698 GHz). The antenna features both horizontally and vertically positioned radiators, each fed by two ports. It demonstrates an extensive overlapping impedance bandwidth (IBW) (S11 < -10dB) of 0.68-0.99 GHz (37.8%), and 1.62-2.99 GHz (61.9%) in the LB and UB for both radiators, with port isolation exceeding 18 dB. Alongside dual polarization and an enhanced FBR, the radiator exhibits a gain beyond 4.8 dBi and a radiation efficiency better than 70%, making it an exceptional choice for applications requiring high-speed wireless communication.

Enhancement of off-body communications with a low-SAR, high-gain multiband patch antenna designed with a quad-band artificial magnetic conductor

Abstract The increasing demand for wireless communication has emphasized the need for multiband antennas. This study presents a novel design for a multiband antenna with reduced specific absorption rate (SAR), high gain, and improved front-to-back ratio (FBR) achieved through the integration with a 4 × 4 artificial magnetic conductor (AMC) surface. The proposed antenna covers a wide range of wireless frequency bands, including Industrial, Scientific, and Medical, Wireless Local Area Network, Worldwide Interoperability for Microwave Access, Wi-Fi 6E, and 7, with resonating frequencies at 2.4, 3.2, 5.5, 7.5, and 10 GHz. The AMC unit cell creates four zero-degree reflection phases with double negative properties at 2.5, 3.8, 5.5, and 7.5 GHz. The compact design measures 0.23λ0 × 0.296λ0 × 0.0128λ0 and placed 0.104λ0 above an AMC surface of size 0.512λ0 × 0.512λ0 × 0.1296λ0. This structure enhances the gain by up to 8.55dBi at 6.01 GHz. The proposed antenna has −10 dB impedance bandwidth for these corresponding frequencies viz 2.34–2.43 GHz (3.77%), 2.81–3.83 GHz (30.72%), 4.82–6.21 GHz (25.20%), 7–7.65 GHz (8.87%), and 8.06–10.31 GHz (24.5%). An overall average percentage reduction value of SAR taken at these frequencies has been found to be 96.11% with AMC structure. The antenna sample was successfully fabricated, and the experimental results have been found to match well with the simulation results. This integrated design offers a promising solution for wearable off-body communication devices.

Highly-efficient tunable dipole-driven Yagi–Uda antenna with end-fire radiation for terahertz application

This paper presents a highly efficient tunable dipole antenna with omnidirectional radiation. The main radiator of the hybrid dipole is designed using a perfect electric conductor, whereas tunability has been achieved using graphene strips in the antenna’s proximity. The dipole antenna resonates at 1.3785 THz and provides a bandwidth (BW) of 8.58% for the graphene’s chemical potential (μc) equal to 0.6 eV. The peak gain and total efficiency (ηTotal) are 1.46 dBi and 83.13%, respectively. The proposed dipole provides tunability from 1.32 to 1.411 THz by varying μc from 0.4 to 0.7 eV. Further, a compact dipole-driven tunable Yagi–Uda antenna has been designed with end-fire radiation. The proposed Yagi–Uda antenna has a size of only 90 μm × 60 μm, i.e., 0.61λg×0.38λg, where λg is the guided wavelength calculated at 1.3631 THz and provides tunability from 1.328 to 1.5 THz. The peak gain, front-to-back ratio (FBR) and ηTotal at 1.3631 THz for the μc = 0.6 eV are found to be 4.93 dBi, 17.3 dB, and 63.36%, respectively. A practical parallel plate DC biasing configuration with a common ground plane has also been proposed to independently tune the μc of each element in the passive Yagi–Uda array. The proposed Yagi antenna provides reasonable gain and FBR to cater for high propagation loss in the terahertz regime.

A novel structure based on ultra-wideband filtering circuit for isolation enhancement of Vivaldi antenna with narrow gap in H-plane

A novel structure based on ultra-wideband (UWB) filtering circuit for isolation enhancement of Vivaldi antenna with narrow gap in H-plane is proposed in this paper. An antipodal Vivaldi antenna array with series of parallel slots in feed arms and a reflective floor is adopted to gain lower profile height, higher front-to-back ratio (FBR), and better isolation in high frequencies compared to a conventional one. The proposed filtering decoupling structure (FDS), composed of three bow ties with slender serrated lines at the edges distributed on both sides of the dielectric plate, is not only located in the necessary path of the spatial coupling of the two units, but also electrically connected with the reflective floor to enhance the low-frequency decoupling effect. The measured results show that the decoupling antenna array works well in 1.8–12 GHz, and the isolation is improved by 24.1 dB at 3.2 GHz and 12.2 dB at 1.9 GHz with FDS. The proposed FDS works well from 1.6 to 4.7 GHz with bandwidth of 96.7%, and the minimum isolation in the operating frequency band is improved from 10 dB to 19 dB. Moreover, the radiation performance remains superior after decoupling. The proposed decoupling structure is potential in the application in large-scale UWB arrays.

Dual-band absorption due to simultaneous excitation of TE and TM modes in ITO-ES metamaterial for IR stealth technology

We proposed a plasmonic based Indium Tin Oxide Embedded Silver (ITO-ES) infrared dual-band perfect absorber for the utilization in IR stealth technology. The proposed structure comprised of nano size Ag ring and desk embedded in ITO. The optical losses in optical regime of nanoscale plasmonic Ag were incorporated in terms of collision frequency using the modified Drude model. The optical response of the proposed structure was predicted by exciting it with a planwave using full wave vector frequency domain solver by employing Finite Element Method (FEM) in Computer Simulation Technology (CST) Microwave Studio. The simultaneous excitation of higher order transverse electromagnetic (TE and TM) modes in the proposed structure lead to high values of both absorption and Front to Back ratio (FTBR). The controlled and selective wavelength multiband absorption is crucial for IR stealth technology. The proposed metamaterial structures exhibit dual-bands IR absorption at wavelengths λ = 1.40 μm and 6.4 μm. First absorption peak suppresses the back scattering of the laser used by laser guided devices for detection, while the second peak suppresses the IR signature of the structure due thermal radiation which can be used by tracking devices to detect warm/hot objects.

A Lightweight Low-Profile GNSS Antenna Based on Wideband Multipath Mitigation Strategy

A new light-weight low-profile antenna based on wideband multipath mitigation strategy for high precision global navigation satellite system (GNSS) is presented. The multipath mitigation strategy is realized by using two shorted rings and several discretely distributed absorbing materials. The two shorted metal rings can improve the spatial axial ratio and broaden the pattern beamwidth, and the absorbing materials significantly enhance the multipath mitigation performance. One prototype of the proposed light-weight GNSS antenna is designed and fabricated for demonstration. The measured results show that the front-to-back ratio (FBR) is over 30 dB across the entire GNSS bands (1.16-1.28GHz and 1.53-1.62GHz). The 3dB spatial axial ratio and 3dB beamwidth is about ±82° and 80°. The proposed antenna performs similarly to its counterpart but with a lighter weight of about 1.2kg and a lower profile size of 70mm.