Showing papers on "Front-to-back ratio published in 2019"

Wideband HMSIW-based slotted antenna for wireless fidelity application

Abstract: In this study, a wideband half-mode substrate integrated waveguide (HMSIW)-based cavity-backed slot antenna is proposed for Unlicensed National Information Infrastructure (U-NII, 5.180-5.825GHz) band. To reduce the size of the antenna, an HMSIW backing cavity is used. An epsilon-shaped radiating slot is etched on the top plane of the cavity to achieve a wide -10dB impedance bandwidth of 13.2% (5.092-5.817GHz). A planar exponential tapered feeding technique is used to excite the slot. A wideband is realised by coupling of hybrid mode, TM 210 mode, and modified TM 020 modes at the resonant frequencies of 5.2, 5.5, and 5.8GHz, respectively. The size of the proposed design including a feeding network is 56mm × 32mm (1.4 λ g1 × 0.8 λ g1 ). The proposed design is fabricated and experimentally tested. The experimental results show gains of 6.6, 6, and 5.5 dBi and efficiencies of 91, 89, and 87% at the frequencies of 5.2, 5.5, and 5.8GHz, respectively, with front-to-back ratio better than 15dB. Moreover, the proposed antenna shows a unidirectional radiation pattern including the advantages of low-profile and lightweight with planar integrity which makes the proposed antenna a favourable candidate for wireless fidelity application.

Compact near zero index metasurface lens with high aperture efficiency for antenna radiation characteristic enhancement

Abstract: In this paper, a high gain, aperture efficient, low profile compact, near zero index (NZI) metasurface (MS) lens antenna with enhanced radiation characteristic is proposed. A high-performance transmissive MS is designed by using modified double circular ring resonator as unit cell with measured 3 dB transmission band from 8.80 to 11.90 GHz. It is observed that a triple layer stacked MS lens has the maximum ability to converge the electromagnetic radiation. The focusing mechanism of multiple stacked MS is studied by using measured E- and H-plane radiation pattern plot and H-Field distribution. A high gain low profile antenna is designed by placing the proposed small single surface NZI MS lens over a microstrip patch antenna acting as a microwave source. The proposed NZI MS lens is found to increase the measured gain of E- and H-plane by 10.70 dB in boresight direction at operating frequency 10.15 GHz. The front to back ratio is improved by 8 and 3 dB in E- and H-plane, respectively. The proposed MS lens antenna is able to achieve a broadside gain of 97.50% of the maximum gain achieved due to ideal effective radiation surface.

A circularly polarized wide-band magneto-electric dipole antenna with simple structure for BTS applications

Abstract: A circularly polarized magneto-electric dipole antenna with wide frequency band for base transceiver station (BTS) is presented. The structure of the proposed antenna is composed of a cavity metallic reflector with defected side walls, two pairs of vertical and trapezoidal horizontal copper plates and a Г-shaped feed line. Defected side walls of the metallic reflector are utilized to improve the gain, front to back ratio (FBR) and impedance matching. Electric dipole and quasi magnetic dipole are realized with horizontal plates and shorted vertical plates, respectively. The trapezoidal horizontal plates are employed to obtain circular polarization (CP) characteristic with 3-dB axial ratio bandwidth of 41% from 1.7 to 2.6 GHz. Experimental results show that the proposed antenna operates at frequency range of 1.4–2.8 GHz with S11

Polarization reconfigurable slot antenna for 5.8 GHz wireless applications

Abstract: A CPW-fed circular polarization reconfigurable antenna is proposed in this paper. The antenna consists of two symmetrically placed inverted L-shaped slots. By using a T-type bias device to change the bias states of two PIN diodes which connect the two slots with the feed port respectively, right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) can be realized accordingly. For both states, the measured −10 dB impedance bandwidth is 5.78–5.96 GHz, while the measured 3 dB axial ratio bandwidth is 5.64–5.91 GHz (4.7%), both the bandwidths can cover the 5.8 GHz ISM band. By using floating ground and reflector board to enhance the front to back ratio of the antenna, 6.84 dBi measured gain can be realized at 5.8 GHz.

An ITO Based High Gain Optically Transparent Wide Band Microstrip Antenna for K Band Satellite Communication

Abstract: A high gain optically transparent microstrip patch antenna for K band (18 GHz–27 GHz) satellite communication has been proposed and investigated in this paper. In order to make sure the property of optical transparency of the antenna, optically transparent materials have been chosen for all the layers of the microstrip patch antenna. Indium Tin Oxide (ITO) film is opted for the radiating patch and ground plane where the substrate is made of pyrex glass (lossy) (Ɛ r = 4.82 and tanδ = 0.0054). The proposed transparent antenna operates at center frequency of 24.8 GHz ranging from 17.625 GHz to 30.523 GHz that covers the entire K band of satellite communication. The transparency property of the patch antenna is useful to minimize the shadowing effect of the solar antenna as well as helpful to guarantee the maximum uses of satellite surface area. The proposed antenna has high IEEE gain of 12.36 dB and directivity of 13.38 dBi including efficiency of 92.38%. It also possesses very wide bandwidth (12.898 GHz), high front to back ratio (16.699 dB) and very good VSWR (1.0566) at center operating frequency.

Compact broadband circularly-polarised antenna with a backed cavity for UHF RFID applications

Abstract: A compact broadband circularly-polarised (CP) antenna is designed with a novel method for universal ultra-high-frequency (UHF) radio-frequency identification (RFID) readers. It is composed of a compact ring-shaped patch which aims to decrease the size of the antenna. A quadrature 3 dB coupler placed below the ground plane creates 90° phase differences to generate the CP radiation of the antenna. To improve the performance of the proposed antenna and minimise its size, the authors use a coupling feeding method, an FR4 dielectric slab, and a metal cavity. The coupled feeding is implemented to eliminate the mismatching between the long probe and the ring-shaped patch, and to improve the gain over the operating band. The introduction of an FR4 dielectric slab and a cavity can reduce the antenna size and improve the impedance matching and axial-ratio (AR) bandwidth. The antenna with a backed cavity can increase the front-to-back ratio remarkably and improve the CP performance further. The measured results show that the antenna with a low profile (0.45 λ 0 × 0.45 λ 0 × 0.06 λ 0 at 915 MHz) has the impedance bandwidth of 30.2% (730-990 MHz) and 3 dB AR bandwidth of 24.2% (760-970 MHz). Both the impedance and the AR bandwidth cover the worldwide UHF RFID band.

A Novel 3D Miniaturized, Wideband, Dual-Polarized Antenna with High Isolation, Low Cross Polarization for Advanced LTE/5G Base Station Application

Abstract: In this literature, a small profile wide band, dual polarized antenna element for Advanced LTE/5G base station for MIMO application is presented. The design consists of a Pair of orthogonal planar bow tie dipoles is fed with a two semi ridge cables and a reflector ground plane with air dielectric are used to obtain the two linear polarizations. The designed antenna is operating in the frequency band of LTE2400 and sub 6GHz (3.3-4.0GHz) band for 5G. A single antenna works for both Advance LTE/5G for MIMO applications. From the simulation results the single antenna element with notch on the dipole arms yields an $\vert S11\vert$ less than-15dB bandwidth of 66.66% (2-4 GHz), HPBW of 71.5 degrees and a gain of 7.5 to 9.3dBi, Front to Back Ratio(FBR) is better than 18.5dB, with Isolation of 35dB,Cross Polarization Level of 38dB with symmetrical radiation pattern. The overall height of the antenna is 34mm with radome and the design is simple and easy to fabricate. Thus, this new design is an ideal candidate for the new 5G Mobile Base Applications.

The Substrate Integrated Waveguide Based Self- Triplexing Cross Slot Antenna

Abstract: The substrate integrated waveguide (SIW) based self-triplexing plus slot antenna is demonstrated in this paper. The proposed antenna comprises of SIW cavity with an etched plus-shaped slot on the patch along with three individual and orthogonal micro-strip feed lines of 50 ohms. Here the plus-shaped slot on the upper metallic is contributed as the "T"-shaped slot, transverse to the respective orthogonal feed lines, and produces the three distinct resonant frequencies of 8.5GHz, 9.7GHz & 12GHz. By properly selecting the proposed antenna dimensions and parameters, the intrinsic isolation of minimum 23dB is attained between any of the two input ports, which determine the self-triplexing property of the proposed antenna. It has the minimum value of the envelope correlation coefficient of 0.02 and a higher front to back ratio. It is also realized the stable and unidirectional gain of 3.5, 4.7 and 5.2dBi.

A Novel Miniaturized Coplanar Waveguide Fed Tapered Slot Ultra Wide Band Vivaldi Antenna For Microwave Imaging Applications

Abstract: This article proposed a novel miniaturized design of coplanar wave guide (CPW) fed ultra wide band (UWB) tapered slot Vivaldi antenna for microwave imaging applications. Broken line exponential tapered profile and different types of slots have been incorporated in order to obtain the better performance and miniaturized antenna. All the important performance parameters of the proposed antenna such as return loss, BW, gain, directivity, VSWR, axial ratio, front to back ratio, accepted power, radiated power, surface current, radiation efficiency have been analyzed and enhanced up to the acceptable level. Finally, from the simulated validation, it is noticed that the proposed antenna would be a potential candidate for microwave imaging applications.

Vertical Polarized 1 × 3 Series-Fed Linear Array with Gain and Front-to-Back Ratio Enhancement for Airborne SAR-X Applications

Abstract: In this paper, a gain and front-to-back ratio (FTBR) enhanced vertically polarized 1 × 3 series-fed linear array for Airborne Synthetic Aperture Radar-X-band applications has been presented. The proposed antenna prototype is designed at 9.65 GHz (X-band). The design consists of a square radiating patch, substrate, quarter wave transformer, 50 Ω matched transformer, and series feed line (SFL). The simulated antenna prototype is fabricated and successfully measured. The final antenna prototype has a dimension 3.256 × 2.035 × 0.0645λg (Guided wavelength) at 9.65 GHz. The results indicate that the proposed antenna prototype yields an impedance bandwidth > 140 MHz (from 9.591 to 9.712 GHz) defined by S11 < −10 dB. The low profile/cost antenna prototype has a fully directional radiation pattern with measured gain up to 12.2 dBi and estimated radiation efficiency of 89%, respectively. A brass plate with 0.8 mm thickness has been fabricated to attach to the antenna ground plane for improving FTBR of more than 30 dB. All these features make the proposed antenna array have good potential applications in X-band system, especially in 9.65 GHz Airborne SAR systems. The aperture of the antenna is 80mm × 50 mm, which equals 31 wavelengths at 9.65 GHz.

Meta-surface enabled hepta-band compact antenna for wearable applications

Abstract: This study proposes a new hepta-band antenna that consists of an inductive ground plane and slots loaded patch for the multiband body-worn scenario. The phase distribution is optimised by considering a 7 × 7 array of periodic square patches on the metallic ground-backed substrate in such a way that resonant modes of patch slots interact with the resonant modes of meta-resonators of inductive ground to achieve hepta-band behaviour with desired radiation characteristics. Each unit cell corresponds to a phase shift of 3.6° out of available phase distribution of 180°. The seven bands are targeted at 1.8, 2.45, 2.96, 3.5, 3.8, 4.2, and 4.5 GHz which supports GSM (1.8 GHz), WLAN (2.4 GHz), LTE (2.5 GHz), Wi-MAX (3.5 GHz), sub-6 GHz 5G band (3.4-4.2 GHz), navigation (2.96 GHz), and satellite (4.5 GHz) applications. It is also demonstrated that an inductive ground plane can be used to get reduced SAR and increased FBR, making antenna useful for wearable applications. The proposed antenna has a patch size of 28.84 × 28.84 mm upon a 0.4 mm thick substrate of permittivity 4.3. Inductive ground is made of via-free periodic square patches each of size 5 × 5 mm on the 2.6 mm thick metallic ground-backed substrate.

Tapered Slot Antenna Covering 6-18 GHz for Electronic Warfare Applications

Abstract: For Electronic Warfare (EW) applications covering Multi-Octave bandwidths several antennas are proposed such as Tapered slot antennas and its variants, Spiral antennas and Loaded patch antennas. In this paper a novel tapering slot Vivaldi radiator operating over 6-18 GHz frequency band for Electronic Warfare applications is proposed. The simulations are carried out using HFSS software and Return loss, Radiation patterns both in Azimuth plane and elevation plane, Gain, Front to Back ratio and Half power beam width have been computed and results are presented.

A dual band flexible antenna on AMC ground for wearable applications

Abstract: A dual band antenna operating at 2.45 and 5.8 GHz ISM bands is proposed for wearable applications. The antenna is simple in design where a coplanar waveguide (CPW) fed structure along with a slot in the patch are responsible for generation of dual band property. As the wearable antenna works in close proximity of the human body so, it is susceptible to various performance degradations. In order to restore the antenna performance, a fully flexible artificial magnetic conductor (AMC) based ground plane is placed beneath the antenna which is found to enhance the front to back ratio, gain and efficiency of the standalone antenna. Additionally, it reduces the specific absorption rate (SAR) of the antenna which is a merit from the wearable point of view.

SIW Based Self-Diplexing Dumbbell Slot Antenna for X- Band Application

Abstract: A design of substrate integrated waveguide (SIW) based self-diplexing dumbbell-shaped slot antenna is presented in this paper. The proposed antenna comprises of two micro-strip feed lines of impedance 50Ω and two parallel dumbbell-shaped slots. These transverse parallel slots are of different lengths, etched on the patch (top surface) of the SIW cavity; produce two resonant frequencies at 8.12GHz & 10.15GHz. The proposed self-diplexing antenna is based on the function of operating mode and perturbation of the higher order modes methodology. The better intrinsic isolation of 26.5dB is obtained between two input ports, which define the unique property of the self-diplexing antenna and reduce the space and size of overall wireless transceiver modules. The proposed antenna produces the unidirectional radiation pattern, high front to back ratio (>17 dB) and gain of 4.7dBi & 5.2dBi at two resonant frequencies of 8.12GHz & 10.15GHz for the X- Band application as satellite and wireless communication systems.

Preliminary Design of Helix-Loaded, High Gain Planar Endfire Circularly Polarized Antenna

Abstract: Conceptual design of a helix-loaded, high gain planar endfire circularly polarized antenna (PECPA) is envisioned. An axial-mode helix is excited by a complementary dipole PECPA at its basic form, while a low profile of about 0.034-wavelength is maintained. In this way, endfire directivity and front-to-back ratio (FTBR) can be enhanced to 7.1dBi and 14dB, respectively. Design considerations with preliminary numerical results on key parameters of the proposed antenna are discussed.

Polycarbonate based flexible antennas for mmWave 5G devices

Abstract: In this paper, low-cost polycarbonate substrate is used for design of antennas operating in the 28 GHz band. First, a corner bent inset fed patch antenna is proposed with a forward gain of 7 dBi and a front to back ratio of more than 18 dB indicating minimal radiation towards the user post-integration with the mobile terminal. In order to cater to the landscape mode: a corner bent tapered slot antenna is also proposed with a gain of 7 dBi An overlapped architecture is investigated to demonstrate orthogonal pattern diversity with an effective radiating volume of 0.12λ 0 3 and a port to port distance of 0.13λ at 28 GHz and mutual coupling of less than 27 dB without deterioration in the pattern integrity of the corresponding modes. A corner bent phased array is also illustrated operating at 28 GHz

Coupling Reduction of Printed Yagi Antenna Arrays for Millimeter-wave Imaging Applications

Abstract: In this paper, methods for reduction of coupling between receiving and transmitting antenna arrays are proposed and tested. Coupling between RX and TX causes saturation and a higher noise level in IF. So, coupling reduction improves image quality of system. Antenna element of arrays are printed antipodal Yagi-Uda antenna with greater than 8 dBi gain and higher than 4 GHz bandwidth. Frequency bandwidth of this imaging system is 27 to 30.5 GHz. Half power beamwidth of this antenna element is larger than 90 dB. Front to back ratio of this antenna is improved in this paper to 30 dB at 29 GHz.

Front to Back Ratio Improvement in Microstrip Antenna Array Using AMC for LTE Applications

Abstract: This paper aims to present an antenna array with Artificial Magnetic Conductor (AMC) surface that operates at the frequency of LTE Band 5 (869 MHz to 874 MHz). In this work, three different prototypes designed and analyzed to improve the front to back ratio of microstrip antenna. First prototype is a single patch microstrip antenna, second prototype is its 2×1 array and in third prototype an AMC is used as ground plane of the array. The final prototype offers 35.79% improvement in the front to back ratio. The simulated results have also been experimentally validated.

Wideband and Compact Magneto-Electric Dipole Antenna for Electromagnetic Medical Imaging Systems

Abstract: A wide band low profile directional magneto-electric antenna is presented. The antenna consists of a half-wavelength bow-tie electric dipole and a one wavelength circular magnetic dipole, both printed on different sides of an FR-4 substrate. The electric dipole antenna is directly fed by a Subminiature Version A (SMA) connector, whereas the magnetic loop is excited using proximity coupling. Two parasitic elements are designed to improve the bandwidth and increase gain. The antenna has wide frequency bandwidth of 80% at 0.7-1.65 GHz with compact size of 0.3 λ0× 0.2 λ0× 0.01 λ0 (where λ0 is wavelength at lowest operation frequency). The antenna achieves a maximum realized gain of 6 dB with peak front to back ratio (FBR) of 15 dB.

Design of an Ultrawideband Directional Antenna Based on a Bidirectional Radiator and a Multilayer Pyramid Absorber

Abstract: An antenna with a unidirectional radiation pattern for level sensing in a storage tank is presented. The proposed antenna configuration consists of a bidirectional radiator and a multilayer absorber. The frequency of operation ranges from 300 to over 1500 MHz with a reflection coefficient of less than −10 dB. By placing the multilayer absorber behind the bidirectional radiator, a stable unidirectional radiation pattern over the frequency range from 300 MHz to 900 MHz can be achieved. The absorber with 3 layers forms a pyramidal shape to absorb the signal at 3 difference frequency ranges namely around 300 MHz, 600 MHz and 900 MHz. This multilayer absorber is used to improve radiation pattern of the slot antenna by absorbing and reflecting the back lobe over the frequency of interest. The front to back ratio has a maximum value of 9.8 dB at 800 MHz.

Planar cavity-backed antenna prototype by groove waveguide technique

Abstract: A new Cavity-Backed Antenna prototype compatible with planar technology is presented is this paper. The topology and circuit design are presented. The antenna is completely manufactured in hard-aluminum. The Cavity-Backed Antenna prototype is designed by using Groove waveguide technique. The new antenna prototype consists of a slotted cavity fed by a microstrip line. Two prototypes were designed and manufactured. The first prototype was designed with three metal walls and the second prototype has been manufactured with two metal walls. In this new antenna prototype the specific slot patterns on the cavity back face such as edge slots and meandered are combined. An example with a minimum 10 dB return loss bandwidth of 1.3%, 6.5 dBi gain, and 21.2 dB front to back ratio has been presented. The new Cavity-Backed Antenna prototype can be used in hyperthermia treatment.

High Gain Compact Circularly Polarized MSA

Abstract: In this paper, a compact dual feed circularly polarized microstrip antenna (CPMSA) is presented using 3-dB 2-branch line coupler as feed network. The antenna size is reduced by 39.9% by cutting slots in circular shaped CPMSA. The antenna characteristics are analyzed using cavity enclosure and radome cover. It increases the antenna bandwidth (BW) and gain. The compact CPMSA provides 26.8% BW for |S 11 | ≤ -10 dB and 3 dB axial ratio (AR) BW of 27% with maximum gain of 6.9 dBi at 2.8 GHz. Cross polarization (X-pol) of lower than -15 dB and front to back ratio (FBR) of more than 12 dB are obtained for the compact CPMSA. The designed antenna is fabricated and experimental results agree well with simulated results. The designed antenna can be used as transmitter and receiver in transponder systems to monitor missile health parameters.

A Compact, Uniplanar Vivaldi Antenna with an Embedded CPW Feed

Abstract: A novel designed, compact uniplanar Vivaldi antenna for microwave imaging is proposed in this paper. With its broad bandwidth and end-fire radiation performance, it is especially suitable for microwave imaging systems. In the proposed antenna, a novel feed structure is proposed. A CPW feed is embedded into the Vivaldi patches, which ensures the whole structure to be compact and simple. The Vivaldi patches leads to wide bandwidth, high gain and very good front to back ratio compared to conventional antennas. The bandwidth is about 14.9 GHz (1.2 - 16.1 GHz) in terms of the 10dB return loss. Gain of the antenna is 7.0 dBi, and the front-to-back ratio is 16 dB.

Broadband high-precision satellite navigation positioning antenna having high front-to-back ratio

Abstract: The invention provides a broadband high-precision satellite navigation positioning antenna having high front-to-back ratio. The broadband high-precision satellite navigation positioning antenna comprises a PCB of an FR4 medium, feeding PIN pins of a plurality of long metals, a 3DB bridge, a supporting metal frame, a metal guiding piece and a metal capacitor compensation piece. The problems of broadband high front-to-back ratio, GNSS full frequency band and the like are solved very well, the design scheme of the broadband and high front-to-back ratio GNSS full frequency band of the high-precision satellite navigation antenna is given emphatically, and antenna gain is effectively increased while the GNSS full frequency band is included.

A Novel Class of Super-elliptical Vivaldi Antennas for UWB Applications

Abstract: In this work, a novel class of super-elliptical antipodal Vivaldi antennas (SAVAs) with enhanced impedance bandwidth of 12.02 GHz is reported. Antenna geometry is designed and printed on a 170.7 mm × 134 mm PCB thin layer by making use of super ellipse equation. The antenna is low cost easy to fabricate with high directional end-fire radiation characteristics. The measured average total efficiency realized gain and front to back ratio is better than 65% 8 dBi and 19.8dB respectively across the operational frequency range (1.28-13.3GHz). A parametric study of four key geometrical parameters of the proposed antenna is made and reported. Measured results of fabricated antenna prototypes are also reported.

Compact Uniplanar MSA with Endfire Radiation

Abstract: A compact uniplanar microstrip antenna (UMSA) for endfire radiation pattern is designed with simple feed. Size of the antenna is compressed by meandering the driven element. It is fed by a simple unbalanced coaxial feed. The antenna characteristics are analyzed by varying the antenna dimensions. The fabricated antenna has size of 0.38λo x 0.11λo at 2.46 GHz. Experimental results of the antenna agree with simulated ones. It provides gain of 5.5 dBi and front to back ratio (F/B) of 12.7 dB. The proposed compact UMSA can be easily integrated with printed circuit boards.

Performance Improvement of a CPW-fed Dual-band Antenna using Swastic-Shaped Asymmetric Artificial Magnetic Conductor

Abstract: A CPW-fed dual wide-band directional antenna is designed, and an investigation carried out to improve the performance of the antenna using asymmetric artificial magnetic conductor is presented. The unit cell of the proposed AMC has a square patch geometry in which four rectangular slots have been etched out. The dual-band antenna is formed by a CPW-fed tapered monopole with V-shaped slot and is backed by a AMC reflector consists of 4 × 4 unit cells. The proposed antenna has dual wide-band response ranging from 2.23-2.81 GHz (580 MHz) and 5.01-6.5 GHz (1490 MHz). The proposed antenna exhibits peak gain improvement of 4.48 dBi and 6.51 dBi at 2.4 GHz and 5.5 GHz respectively and has directional radiation pattern with front to back ratio (FBR) of 20.22 dB and 29.49 dB at 2.4 GHz and 5.5 GHz respectively. The proposed antenna also exhibits bandwidth improvement as compared to the antenna without AMC reflector over both 2.4 GHz and 5.5 GHz bands.

Design of a Miniaturized Low-Profile Archimedean Spiral Antenna with Tapered Balun Transformer

Abstract: In this paper, a miniaturized low-profile Archimedean spiral antenna is proposed. The antenna is complementary itself and fed by a tapered coaxial balun transformer, which is an impedance matching transition from coaxial line to a balanced, two-conductor line, to match the balanced structure. The proposed antenna is only 0.015 wavelength in height at the lower frequency, which is used as the antenna unit consisting a 5-unit antenna array. Simulation results in HFSS are discussed. The axial ratio of the 5-unit antenna array is less than 3.5dB. The front to back ratio is larger than 25dB and the HPBW is about 60°. The isolation between two antenna units is better than 30 dB and the VSWR is less than 1.8. The simulation results demonstrate that with low profile and limited aperture, the proposed antenna shows potential application in communication system.