Showing papers on "Front-to-back ratio published in 2021"

Near-zero-refractive-index metasurface antenna with bandwidth, directivity and front-to-back radiation ratio enhancement

Abstract: In this paper, a novel metasurface-based Fabry–Perot Cavity antenna is presented The antenna is wideband, directive and has a high front-to-back ratio The idea of the antenna is based on loading

A novel wideband fractal rectangular dielectric resonator antenna with improved radiation performance

Abstract: A wideband fractal rectangular dielectric resonator antenna (RDRA) based on the hook-shaped dipole is proposed for wireless communication, which exhibits stable, symmetric radiation patterns and low cross-polarization. The antenna consists of a Koch-like fractal rectangular dielectric resonator antenna (FRDRA) and a hook-shaped electric dipole (HSE-Dipole), which are equivalent to the magnetoelectric (ME) dipoles. The symmetrical radiation pattern with gain enhancement and suppression of backward lobe is achieved by the complementary combination of the electric and magnetic dipoles. The Koch-like fractal structure is used to improve the impedance matching of the RDRA with 15% size reduction. The antenna is excited by the substrate integrated waveguide (SIW) feeding network, which takes the advantage of compact size and low insertion loss. Due to the air gap between the FRDRA and HSE-Dipole, the fundamental TE1δ1 and high-order TE1δ2 modes of the RDRA are both generated to obtain the 19.5% impedance bandwidth. The prototype is fabricated and measured to validate the antenna design, which shows remarkable radiation performance including the front to back ratio (FTBR) of >20 dB, the average gain of 5.96 dBi and low cross-polarization.

Via-less electromagnetic band-gap-enabled antenna based on textile material for wearable applications.

Abstract: A compact fabric antenna structure integrated with electromagnetic bandgap structures (EBGs) covering the desired frequency spectrum between 2.36 GHz and 2.40 GHz for Medical Body-Area Networks (MBANs), is introduced. The needs of flexible system applications, the antenna is preferably low-profile, compact, directive, and robust to the human body's loading effect have to be satisfied. The EBGs are attractive solutions for such requirements and provide efficient performance. In contrast to earlier documented EBG backed antenna designs, the proposed EBG behaved as shielding from the antenna to the human body, reduced the size, and acted as a radiator. The EBGs reduce the frequency detuning due to the human body and decrease the back radiation, improving the antenna efficiency. The proposed antenna system has an overall dimension of 46×46×2.4 mm3. The computed and experimental results achieved a gain of 7.2 dBi, a Front to Back Ratio (FBR) of 12.2 dB, and an efficiency of 74.8%, respectively. The Specific Absorption Rate (SAR) demonstrates a reduction of more than 95% compared to the antenna without EBGs. Moreover, the antenna performance robustness to human body loading and bending is also studied experimentally. Hence, the integrated antenna-EBG is a suitable candidate for many wearable applications, including healthcare devices and related applications.

Novel Miniaturized All-Metal UWB Magneto-Electric Monopole (MEM) Antenna for Multistandard Applications

Abstract: We propose a novel miniaturized all-metal ultrawideband (UWB) magneto-electric monopole (MEM) antenna in this communication. The proposed antenna is composed of a half-ellipse electric monopole and a quarter magnetic loop. The half-ellipse electric monopole consists of a half ellipse with a rectangular slot, a loaded patch, and an L-shape ground fed by a coaxial connector. Enhanced robustness to severe surrounding environments and lower loss can be achieved by employing an all-metal structure instead of the structure including dielectric materials. A prototype was fabricated and measured. Results show that the proposed MEM antenna can operate in the frequency band of 2.5–13 GHz even higher frequency with the miniaturized dimensions of $0.25\lambda \times 0.24\lambda \times 0.17\lambda $ that is much smaller than a magneto-electric dipole. A unidirectional wide beam radiation pattern with a 10 dB front to back ratio can be obtained. Moreover, the group delay is analyzed which reveals the antenna with good time domain characteristics. The proposed MEM antenna can be employed as a multifunctional antenna operating for multistandard communication networks in a limited space.

An end-fire low profile patch antenna to work on WiMAX frequencies used for harvesting power supply

Abstract: In this paper, an end-fire microstrip patch antenna (MPA) is proposed of 3 GHz as a center frequency, designed, simulated, and measured to work on WiMAX frequencies within standard of 802.16e (WiMAX). A high gain ranged between (12.117-13.324) dB, high front to back ratio (F/B) of (35.770) at the center frequency, a wide band of 1.701 GHz, low profile, and semi-ideal voltage standing wave ratio (VSWR) of 1.053 is achieved. The simulation is done using computer simulation technology (CST-MW). The proposed design is based on two Fire-retardant substrates (FR-4) of relative permittivity (e) 4.3+j0.025 and 1.53 mm thickness for each one, which is considered a high loss material. The measurement results show good agreement with the simulated results. In addition, the design can be used for harvesting power supply from mobile towers. Finally, the proposed design is compared with two other designs in terms of power conversion efficiency and overall size.

Proposal and design of an end‐fire slot antenna with low back‐lobe and improved front‐to‐back ratio

Abstract: This paper has proposed an end-fire slot antenna with back-lobe level suppression and front-to-back ratio (FBR) improvement. At first, the radiation characteristic of the conventional λ/4 slot antenna are meticulously investigated to initially demonstrate that its FBR can be maintained as high as about 6 dB. Then, the antenna under three different boundary conditions is deeply studied. The results reveal that the currents along the two sides of the metal ground are parallel to the slot radiator, resulting to affect the back-lobe radiation level to a great degree. As such, a pair of rectangular slots is properly etched on the two sides of the metal ground for further reduction of back-lobe radiation level and FBR improvement. Finally, a prototype antenna operating at 4.7 GHz is designed and fabricated. The measured results demonstrate that the back-lobe is indeed greatly decreased as predicted and the measured FBR of the proposed slot antenna exceeds 25 dB, where an increment of about 19 dB than the conventional λ/4 slot counterpart is successfully obtained, thereby evidently exhibiting better end-fire radiation performance.

A Compact Dual Frequency SICL based Cavity Backed Slot Antenna with High Front to Back Ratio for Millimetre Wave Application

Abstract: This paper presents a compact dual frequency Substrate Integrated Coaxial Line (SICL) based Cavity Backed Slot Antenna (CBSA). A primary slot along with secondary slot is etched on the bottom plate of SICL cavity to generate two non-adjacent resonant frequencies. The primary slot is placed such that it is excited by ${\text{TE}}_{110(even)}^x$ mode of the SICL cavity. The secondary slot is placed near the primary slot and excited by the SICL feed line. At second resonance, SICL cavity acts as the reflector for the back radiation and significantly improves front to back ratio (FTBR). The size of the proposed SICL cavity backed slot antenna is found to be compact in comparision with other technologies based design including Substrate Integrated Waveguide (SIW) cavity backed antennas proposed earlier. The antenna resonates at 24 GHz and 38 GHz with gain of 5.1 dBi and 4.8 dBi, exhibiting high FTBR of 14 dB and 28 dB with co to cross polarization ratio of -22 dB and -32 dB respectively. This antenna finds its application in millimetre wave band 5G spectrum coverage for customer premises equipments (CPE).

Transparent Wideband Circularly Polarized GNSS Antenna for Vehicular Applications

Abstract: In this paper, a single-layer one-sided wideband coplanar waveguide (CPW)-fed transparent circularly polarized (CP) rectangular slot antenna with tilted beam is proposed. The antenna is designed on a glass substrate with a mesh grid in the conductive layer in order to increase the transparency. Since most of the vehicles’ windshields are inclined for about 30 degrees, the beam of the antenna is designed to be tilted for about 30 degrees in elevation. For measurement verification, an inclined stage is fabricated to resemble the inclined surfaces (such as the windshields). The 10-dB impedance bandwidth of the antenna is 40.8% (1.13 - 1.71 GHz) with a 3-dB axial ratio bandwidth of 47.4% (1.06 - 1.72 GHz) and a 3-dB gain bandwidth of about 54% (1.02 - 1.78 GHz) with a maximum right handed circular polarization (RHCP) gain of 5.3 dBic. Also, the transparency of the antenna is about 95%. Therefore, the antenna is a good candidate for vehicular applications such as location tracking, using global navigation satellite system (GNSS) and specifically global positioning systems (GPS). Furthermore, a small-size transparent reflector is designed to be used below the proposed antenna in order to increase the front to back ratio (FBR).

Planar Vertically Polarized Unidirectional Dielectric Radiator Fabry–Perot Antenna Fed by Embedded Thin Slotted Substrate Integrated Waveguide

Abstract: This work devises and investigates a Fabry–Perot-styled planar unidirectional dielectric radiator (UDR) antenna fed by a thin embedded slotted substrate integrated waveguide (SIW). The proposed UDR-SIW antenna consists of two identical dielectric substrates and an embedded feeding SIW between the two dielectric substrates. This diligently mingled multilayer structure makes it possible to not only use the thick dielectric substrates to narrow down the E-plane pattern for symmetrical radiation but also facilitate its integration with RF subsystems through the thin embedded feeding SIW, thereby achieving a compact size and an effective excitation. An experimental prototype of the URD-SIW antenna is simulated, fabricated, and measured. It features a size of $2.96\lambda _{0}\,^\ast \,0.65\lambda _{0}\,^\ast \,0.33\lambda _{0}$ and a nearly symmetrical endfire radiation pattern. The antenna presents a measured impedance bandwidth of 9.4% from 26.3 to 28.9 GHz, a gain varied from 8.2 to 10.3 dBi, which is over 10 dBi from 27.7 to 28.4 GHz, and a front to back ratio over 20 dB from 27.5 to 29 GHz. The proposed UDR-SIW antenna has vertically polarized radiation pattern that is different from a conventional UDR antenna; thus, it is an appropriate candidate to replace the SIW H-plane horn in certain applications.

Multi-Layer Multi-Dielectric Lens Loaded SIW Horn Antenna for Ku-Band Applications

Abstract: This paper presents a wideband substrate integrated waveguide (SIW) horn antenna with enhanced gain and front to back ratio (FTBR) for Ku-band applications. The proposed antenna is realized by placing an elliptical multi-layer multi-dielectric lens (EMLMDL) at the radiating aperture of a probe-fed thin (h 1 = λ 0 /13) SIW H-plane horn antenna. The top and bottom layers of the EMLMDL are realized by high-k dielectric material having relative permittivity 10.2, where as the middle layer is the extension of SIW horn aperture. This three layer arrangement reduces the aperture mismatch over a wide frequency band and improve gain and FTBR while maintaining the overall thickness of EMLMDL to 0.2λ 0 (λ 0 , being calculated at center frequency). The proposed antenna exhibits measured impedance bandwidth of 34% (12.9-18 GHz). The end-fire radiation pattern is fairly stable over the entire Ku-band with FTBR better than 12 dB. The peak gain variation over the operating band is 8.5-11.0 dBi.

3D-printed High-Directivity H-plane Horn Antenna with High Front-to-back Ratio Using Soft and Hard Walls

Abstract: We employ hard and soft walls to improve antenna directivity and front-to-back ratio of an H-plane horn antenna. Design of this class of antenna has been limited by fabrication methods. While machining methods limit fabrication of 3D designs with complex interior shapes, SIW technology restricts the design to planar structures, foregoing benefits of 3D designs and forcing use of dielectric materials that are lossy. With the advent of 3D-printing technology for antenna and microwave devices, however, 3D hard and soft walls can be integrated in an H-plane horn antenna, improving its performance, which is not possible with conventional fabrication methods. Here, an H-plane horn antenna is designed and 3D-printed at X-band. Using hard and soft walls, directivity and front-to-back ratio are improved by 2.25 dB, and 13.7 dB, respectively, compared to an standard H-plane horn antenna, while the bandwidth covers X-band with lower return loss. The measurement results of the 3D-printed and conductive coated antenna are in good agreement with simulations.

Broadband, Beam-Steering Asymmetric Stacked Microstrip Phased Array with Enhanced Front-to-Back Ratio

Abstract: The backward radiation is a critical problem that may cause breakdown of the front-end circuits that are integrated behind the antenna. Thus, antennas having high Front to Back Ratio (FBR) are required. For phased arrays, the back lobe suppression is required for all scanning angles at all frequencies of the band. In this work, a stacked patch linear array with asymmetric configuration is proposed. It is capable of scanning the beam in ±40° with less than 1.34 dB scanning loss. Due to the usage of probe-fed stacked patches as the antenna elements, impedance matching in 8-10 GHz is achieved. More than 30 dB FBR is obtained for broadside radiation. It is above 20 dB when the beam is steered to θ = 40°. This is valid for all frequencies of the band. A prototype is fabricated and measured. Higher than 38 dB FBR is observed. With its broadband, high FBR and low scanning loss, the proposed asymmetrical stacked patch phased array is suitable as radar and base station antenna.

Substrate Integrated Isosceles Trapezoid with Extended Ground Antenna for X-band Applications

Abstract: A Substrate Integrated Isosceles Trapezoid extended ground antenna with dual band characteristics is presented. Simultaneous achievement of high bandwidth, gain and front to back ratio is challenging in the X-band applications. A slot and isosceles trapezoid structure is placed on the top plane of the cavity for radiation. The half mode is realized by splitting the full mode Substrate Integrated Waveguide along the perfect magnetic conductor walls for size reduction. In the open edge of the patch, two rectangular slits are loaded, to effectively enhance the bandwidth performance and improved front to back ratio which are required for X-band applications. The proposed antenna provides a gain of 7.4 dB with front to back ratio more than 10 dB throughout the bandwidth of 20.14%. This dual band antenna operates at 8.6 GHz and 10.19–12.69 GHz.

High Front-to-Back Ratio Dual-Polarized Antenna-Coupled Electrode Electro-Optic Modulator for 28 GHz Band Near Field Antenna Measurement

Abstract: We have developed a simultaneously receiving type dual (orthogonally) polarized antenna-coupled-electrode electro-optic (EO) modulator for 28 GHz-band 5th generation mobile communication as a receiving antenna. Our developed EO modulator can measure the orthogonally polarized microwave signal simultaneously. Cross-polarization discrimination ratio for E-plane of the EO modulator is more than 18 dB, and Front to back ratio is more than 33 dB for the frequency range from 27 to 29.5 GHz, respectively. Further, we show a near field radiation patter measurement result for a WR-28 standard gain horn antenna using our developed EO modulator.

A Low-Profile Dual-Polarized Antenna with High Isolation and High Front-to-Back Ratio for 5G Base Stations

Abstract: A dual-polarized, broadband, slot-coupled patch antenna design is presented for sub-6 GHz 5G base stations. Proposed antenna is made up of two suspended stacked patches above feedline layer and is excited by crossed elliptic-H slots for ±45o slant, linear dual polarized operation. Prototyped antenna has an impedance bandwidth of 22.1% (3.14 - 3.92 GHz) for |S11|, |S22| 27 dB) without reflector. Design details, numerical studies, and measurement results are presented.