VSWR Bandwidth Research Articles

A compact wideband circularly polarized dipole antenna with wide beamwidth

AbstractA wideband circularly polarized (CP) dipole antenna with compact size and wide beamwidth is proposed. To achieve a wide half‐power beamwidth (HPBW), the dipole is designed to be a folded bowtie, and four rotationally symmetric vertical metal plates are placed on the square ground plane. A circular parasitic patch above the dipole arms improves the impedance bandwidth. By using a 3‐dB coupler, the proposed antenna achieves wideband CP performance. The measured results show that an impedance bandwidth for VSWR ≤ 2 and a 3‐dB axial‐ratio (AR) bandwidth are from 0.76 to 2.1 GHz (93.7%). Moreover, a bandwidth of HPBW ≥ 102° is from 0.76 to 1.8 GHz (81.2%).

A broadband mono‐cone antenna employing a shorted parasitic ring and parasitic metal pillars

AbstractThis letter proposes a broadband mono‐cone antenna with a shorted parasitic ring and parasitic metal pillars. Four parasitic metal pillars expand the high‐frequency operation band, while a shorted parasitic ring increases the current flow path and expands the low‐frequency operation band. A 148.3% impedance bandwidth for VSWR ≤ 2 from 0.831 to 5.6 GHz is attained. The antenna has stable radiation performance across the entire operation spectrum. The simulated and measured results show a good agreement. It is exceptionally compatible with GSM900, DCS1800, PCS1900, UMTS, IMT2000, WiBro, WiMAX2350/3500, LPWAN, wireless LAN (IEEE 802.11b), and a portion of the WLAN/Wi‐Fi frequency spectrum. Indoor applications such as wireless energy collection, partial discharge detection, and so on are possible for the proposed antenna.

Improved Ground Radiation Antenna Performance for a Vertically Attached PCB

A small, loop-type ground radiation antenna for 2.4-GHz WLAN applications in the complex ground with two vertically attached printed circuit boards (PCBs) was designed. In the presence of a vertical PCB (sub-PCB), the antennas in two different positions, far from and near the sub-PCB, were designed. The current distribution of the complex PCB was stronger near the sub-PCB. Therefore, the coupling between the antenna and the complex PCB was stronger when the antenna was located near the sub-PCB. The antenna close to the sub-PCB obtained more than twice the 3:1 VSWR bandwidth and the efficiency bandwidth than the distant antenna.

An Extremely Wideband Tightly Coupled Dipole Array With Shared-Aperture Configuration

The intent of this letter is to expand the tightly coupled dipole array (TCDA) concept in a shared-aperture configuration for high radiation efficiency and extremely wide bandwidth. Specifically, a high-band TCDA is deployed beneath the aperture of a low-band TCDA. With this configuration, the profile height keeps the same as that of a stand-alone low-band TCDA. It offers a thin λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> /13.7 (or 1.7λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</sub> ) array with 23.2:1 bandwidth for active VSWR < 3, where λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> and λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</sub> are the wavelengths at the lowest and highest frequencies of the operating frequency band. Although the shared-aperture configuration is profit for low profile and bandwidth extension, it causes cross-band coupling and deteriorates radiation performance. To solve this issue, the low-band TCDA is designed to be electromagnetic transparent to the high-band electromagnetic waves. The two TCDAs become immune to the cross-band interference and operate properly as in their stand-alone cases. An array prototype consisting of a 16 × 16 high-band array and an 8 × 8 low-band array is fabricated and measured. The measured radiation efficiency is demonstrated to be 77% on average across a 23.2:1 bandwidth.

A 3-D Printed Ultrawideband Magnetoelectric Dipole Antenna With Ridged Waveguide Aperture-Coupled Feeding

A ultrawideband magnetoelectric dipole (MED) antenna fed by a ridged waveguide is presented in this letter. Different from the widely used Γ-shaped probe feeding structure, a novel ridged waveguide aperture-coupled feeding technology is employed to excite the MED antenna and an ultrawideband MED antenna with an impedance matching of 104% from 1.92 to 6.08 GHz and directional pattern is realized. To verify this design, an antenna prototype is fabricated using the metallic three-dimensional printing technology. The measured impedance bandwidth of VSWR < 2 is 104% from 1.99 to 6.14 GHz. The directional patterns with a stable gain varying from 5.5 to 7.5 dBi are achieved. Besides, high radiation efficiency of above 89% is obtained owing to its all-metallic structure, which avoids the dielectric loss.

Aperture-Fed Quad-Port Dual-Band Dielectric Resonator-MIMO Antenna for Sub-6 GHz 5G and WLAN Application

A four-port dielectric resonator-based connected ground multiple-input multiple-output (MIMO) antenna is designed. The presented antenna was excited through the aperture feeding technique. The dual bands are achieved by optimally feeding the rectangular dielectric resonator through engineered triangular slots. The antenna has operating modes of T E 111 X and T E 111 Y at 4.5 GHz and 5 GHz, respectively. It presents a 2 : 1 VSWR bandwidth of 2.64% (4.48 GHz–4.60 GHz) and 1.2% (4.96 GHz–5.04 GHz) in the lower and upper bands, respectively. The edge-to-edge distance between array elements is around 7.5 mm. The single antenna dimension is 30 mm × 30 mm, whereas the four-port antenna dimension is 60 mm × 60 mm. The optimum isolation was achieved by carefully placing the antenna elements on the substrate through multiple iterations. The antenna provides port isolation better than 20 dB at both resonances with full ground profile. The advantage of the antenna is that it provides fair antenna and MIMO parameters without additional isolation techniques. The antenna has efficiency in order of 88.02% and 86.31%. The peak gain is 7.67 dBi and 8.32 dBi at 4.5 GHz and 5 GHz, respectively. The optimum envelope correlation coefficient (ECC) is 0.037, channel capacity coss (CCL) is 0.2 bits/sec/Hz, diversity gain (DG) is 9.99 dB, and total active reflection coefficient (TARC) is −18.87. The antenna elements are orthogonally placed with adequate separation to achieve polarization diversity and spatial diversity. The antenna provides the utilization in Sub-6 GHz 5G and WLAN communication applications.

2–18 GHz balanced antipodal Vivaldi conformal phased array antenna with resistive load and shorting posts

In this paper, a 2–18 GHz balanced antipodal Vivaldi conformal phased array antenna is proposed. Firstly, the conformal array achieves a low profile of 0.11λLow by using the tightly coupling mechanism. Here, the gap-induced element resonance (GIER) and the common mode resonance occur in the operating band, limiting the impedance bandwidth. Thus, the resistors are loaded to eliminate the GIER by suppressing the resonant current. Furthermore, the shorting posts are used to remove the common mode resonance by decreasing the resonant length. A transition structure between the stripline (SL) and the ground coplanar waveguide (GCPW) is designed to feed the antenna. The simulated results show that the array achieves a 9:1 bandwidth (2–18 GHz) for active VSWR <2.5 at broadside. Besides, the active VSWR is less than 2.5 for ±60° scanning in E-plane and 3.8 for ±45° scanning in H-plane. A 12 × 8 array prototype is fabricated and measured to validate the performance of the array. The measured results show a good agreement with the simulation.

Design of a Low-Profile Wideband Magnetoelectric Dipole Antenna with Reduced Gain Drop

In this paper, a novel low-profile magnetoelectric (ME) dipole antenna with wideband is presented. The conventional vertical fixing structure is bended four times from the center to the sides. The Γ-shaped feeding structure is bended two times to lower the height of the antenna step by step. The effect of three kinds of vertical wall is discussed to show their influence on boresight gain. Through comparison, only one vertical wall is erected on the left side of the ground to decrease the boresight gain drop at 2.2 GHz. Both simulation and analysis are made to sufficiently explain the working principle. At last, the proposed ME dipole antenna has only 0.095λ0 (λ0 is the center operating wavelength in free space) in height, and the wideband property is still maintained. By simulation, the relative bandwidth for VSWR &lt; 2.0 is 47.9% (from 1.35 to 2.2 GHz). The boresight gain ranges from 8.1 to 9.6 dBi in the operating band. The measured relative bandwidth for VSWR &lt; 2.0 is 50.3% (from 1.34 to 2.24 GHz), and the boresight gain ranges from 7.38 to 8.73 dBi. The gain drop on boresight is less than 1.4 dBi. Radiation patterns show a unidirectional characteristic in the whole operating band. Additionally, the cross-polarization level is less than −25 dB on boresight. The simulating and measuring results agree well with each other. Therefore, the proposed antenna is suitable for applications of limited height and wideband.

GROUND MODIFIED ELECTRICALLY SMALL ANTENNA FOR DCS 1800 APPLICATIONS

A Uni-planar coplanar waveguide fed modified ground radiating structure with very compact size and simple structure, suitable for Global System for Mobile 1800 DCS application is discussed. Developed antenna offers a 2:1 VSWR bandwidth of 180 MHz ranging from 1.71 GHz to 1.89 GHz which is wider to cover both uplink and downlink bands of GSM1800. Antenna possesses linear polarization characteristics and offers a radiation pattern just like a quarter wave monopole. Developed antenna offers an average and uniform gain of 2.1 dBi with a moderate gain of 79.8% in the entire band of operation.

A low‐profile and wideband circularly polarized patch antenna using four resonance modes

In this paper, a low-profile and wideband circularly polarized patch antenna using four resonance modes is presented. It is one kind of four-port antenna implemented by loading five shorting pins on the circular patch. In order to achieve wideband properties, TM11 and TM22 modes are stimulated in circular patch, along with their polarization orthogonal modes (TM11+ and TM22+ modes). The TM11+ mode is excited by the Γ-shaped feed, while the TM22 mode and TM22+ mode is stimulated by four shorting pins in close proximity to the Γ-shaped feed. Due to the strong coupling between shorting pins and Γ-shaped feed, the peak electric field generated on the two opposing shorting pins causes the magnetic current density on the circumference of the patch to be changed, which in turn leads to the realization of broadside radiation in the TM22 and TM22+ modes. In addition, the function of the shorting pin loaded in the center of the patch is to improve the impedance matching when TM22 and TM22+ modes are operated. Cooperated with the devised one-to-four feed network with equal amplitude and progressive phase difference of 90°, the wideband circularly polarized patch antenna is obtained. To verify this design concept, a prototype is fabricated and measured. The diameter of the patch is 0.68λ0 and the profile is 0.078λ0 (λ0 is the wavelength in the free space at the center frequency). The measured relative bandwidth of VSWR < 2 is 106%, involving 1.53–4.96 GHz, while that of AR < 3 dB is 98%, ranging from 1.54 to 4.48 GHz. Besides, the measured LHCP gain > 3 dBic in the frequency band of 1.48–4.42 GHz.

A novel dual‐linear polarized ultra‐wideband magneto‐electric dipole antenna with gain improvement

A novel magneto-electric dipole antenna with dual linear polarization, ultra-wideband, and good unidirectional radiation is proposed. It consists of two bowtie-shaped electric dipoles, two orthogonally placed Γ-shaped feeding structures, four parasitic patches, and a metal cylindrical cavity. In order to illustrate the operating mechanism, the radiation field is simulated and analyzed at lower, medium, and higher frequencies. Three operating modes (electric dipole mode, ME dipole mode, and magnetic dipole mode) are found and discussed to show the ultra-wideband radiation. Especially, the ME dipole mode is analyzed in detail. By adding four parasitic metal patches, the boresight gain at the lower and higher bands is enhanced. At 1.75 and 5.6 GHz, the boresight gain improves 1.65 and 2.8 dB, respectively. Additionally, the height of the cylindrical cavity is also analyzed to show its effect on VSWR and boresight gain. Finally, a prototype is designed, fabricated, and measured. Measured results show that the impedance bandwidth for VSWR <2 is up to 92.3% (from 2.1 to 5.75 GHz) and 103% (from 1.8 to 5.65 GHz) at the two feeding ports, respectively. In its impedance bandwidth, the boresight gain is 8.75 ± 1.95 dBi and 8 ± 3.3 dBi at two ports, respectively. And, the radiation patterns in the operating band show a unidirectional radiation characteristic. Therefore, the proposed antenna can be a candidate in the future UWB communication system.

Probe-location Optimization in a Wideband Microstrip Patch Antenna using Genetic Algorithm, Particle Swarm and Nelder-Mead Optimization Methods

A comparison among three different optimization algorithms, for seeking the best probe location in a wideband microstrip patch antenna, with the objective of bandwidth enhancement, is presented in this paper. As an illustrative example, a rectangular microstrip patch antenna is designed on a TMM-6 substrate, at a center frequency of 3.75 GHz, using the design approach proposed earlier by the present authors. The initial probe location of the design, which is shown to yield 32.66 % 2: 1 VSWR bandwidth, is further optimized using the in-built Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and Nelder-Mead Simplex algorithms, that are available in FEKO.

Coplanar Waveguide-fed Electrically Small via-less Antenna for Dual Band Applications

In this paper, a simple coplanar waveguide fed compact electrically small antenna for dual-band operations without the use of via is presented. The resonances of the structure are obtained by spiraling one of the ground planes of an open-ended CPW transmission line with a short length center feed. The proposed antenna has a geometrical dimension of 0.079λ 01 × 0.079λ 01 mm2 (λ 01 is the free space wavelength of first resonant frequency) with a small electrical size (ka) of 0.35. The experimental studies on the fabricated prototype of the proposed antenna show a 2:1 VSWR bandwidth up to 2.53% and 4.12% for 2.3 and 5.3 GHz, respectively. The simulated antenna reflection and radiation characteristics are demonstrated with physical measurements.

Design of Wideband Cylindrical Dielectric Resonator Antenna Excited using an L-strip Feed

This paper proposes a Wideband cylindrical dielectric resonator energized with an L-strip feed which is focused to be used for wideband application. The objective of this project is to optimize antenna parameters and thereby study the effects of antenna dimensions Length (L), Width (W) and substrate parameters, relative dielectric constant, substrate thickness on its performance. The novel exciting technique achieves a 2:1 VSWR bandwidth of 17%. This project introduces to design antenna operating at 4.02GHz based on the CDRA radius of 10 mm and height of 10mm. The variation of percentage of bandwidth for different feed (simple feed and T feed) parameters is also studied. HFSS software will be used to design a CDR antenna.

Design and development of 4 × 4 MIMO antennas for smart 5G devices

The 5G technology will revolutionize the world more than 3G or 4G. 5G means a world where not only people but all the things are also connected. Thus, a new version of wireless technology gives us a lot of advantages which include a boost in speed, reduce reluctance, and provides a more reliable connection for a wide range of users. In this paper, the design of 5G Multiple Inputs and Multiple Outputs (MIMO) antenna structure is proposed. Also, an inset feeding technique is being used. MIMO is the means for improving the capacity of the radio link. It provides higher data rates and reliability which also operates at millimeter-wave (mm-wave) frequency. The patch antenna is designed to resonate at a 29 GHz frequency. The FR4 epoxy, a dielectric substrate is used in the proposed design which has a dielectric constant (er) of 4.4 and thickness (h) of the substrate is 1.6 mm. In this work, Ansys HFSS software is used to design and simulate the MIMO antenna system. At a desired frequency of 29 GHz, the multiple antennas are resonated with better S11, low VSWR, higher performance, and high bandwidth.

Dual Band Dual Linear Polarized Equal Cross Track Beam Microstrip Antenna for Airborne SAR

This paper presents the design of common aperture dual band dual linearly polarized microstrip array antenna, working at L and S-band for airborne synthetic aperture radar (SAR). The antenna has been designed to offer equal beamwidth across the track of aircraft at both bands. The probe fed square annular patch antenna at L-band and electromagnetically coupled stacked patch antenna at S-band have been selected as array elements and distributed in 2 × 6 and 2 × 12 arrays on the same aperture, respectively. The aperture size is 0.35 × 1.2 m. The antenna has been developed and characterized in the compact antenna test field. The achieved 1:2 VSWR bandwidth is 200 MHz at L-band and 400 MHz at S-band. The measured peak gain is 16.3dBi at 1.25 GHz and 19.0dBi at 3.2 GHz. The developed antenna has also resulted in greater than 30dB port-to-port isolation and cross-polarization at both frequencies.

An approach to achieve directional low‐profile antenna of quintuple stable pattern band by utilising dipole with compound concave corrugated reflector

An approach to achieve directional low-profile UWB antenna by omnidirectional source with a reflector, is proposed. The general theoretical model about the direction and the phase conditions between the upward and reflected field are developed. A bow-tie dipole source antenna is investigated first. To modify its radiation defect, proper phase equations between the original upward field and the reflected downward field are derived so that the aperture field becomes uniform enough to guarantee directional radiation. The concave-shaped reflector is primarily adopted to satisfy the phase conditions. Then the concave-shaped reflector is decorated with corrugated structure to realize good impedance matching within the wide band. Consequently, the split beams caused by multiple long linear currents with phase difference at high frequency is focussed while the directivity at low frequency is also improved. The prototype antenna was fabricated with a profile of 20.5 mm, about 0.156 λ max (maximum wavelength in the work band), and the measured impedance bandwidth of VSWR ≤ 2.2 is over 2.27–26 GHz. Both simulated and measured results demonstrate the stable directional patterns within the quintuple band (2–10.5 GHz). The realised gain is over 7 dBi within the band (2–10.5 GHz) and peak is over 12 dBi.

A Low-Profile HF Meandered Dipole Antenna with a Ferrite-Loaded Artificial Magnetic Conductor

In this paper, a low-profile HF (high-frequency) meandered dipole antenna with a ferrite-loaded artificial magnetic conductor (AMC) is proposed. To operate in the HF band while retaining a compact size, ferrite with high permeability is applied to the unit cell of the AMC. The operating frequency bandwidth of the designed unit cell of the AMC is 1.89:1 (19–36 MHz). Thereafter, a meandered dipole antenna is designed by implementing a binary genetic algorithm and is combined with the AMC. The overall size of the designed antenna is 0.06×0.06×0.002 λ3 at the lowest operating frequency. The proposed dipole antenna with a ferrite-loaded AMC is fabricated and measured. The measured VSWR bandwidth (&lt;3) covers 20–30 MHz on the HF band. To confirm the performance of the antenna, a reference monopole antenna which operates on the HF band was selected, and the measured receiving power is compared with the result of the proposed antenna with the AMC.

Biodegradable nanocomposites dielectric resonator antenna for wi-fi applications

In the modern world of communication where gadgets are becoming smaller, light weight compact antennas also an essential need of the hour. Considering the disposal of electronic equipment’s, if the devices are biodegradable that will be ecofriendly. Considering these, a Cylindrical Dielectric Resonator Antenna (CDRA) manufactured using jute is studied in this paper. In the proposed antenna Low Density Poly Ethylene (LDPE) acts as the binder. To enhance the properties of the CDRA Titanium Dioxide (TiO2) is also incorporated. So the final CDRA has jute, LDPE and TiO2 in the ratio 30:50:20. With this chemical composition a CDRA of radius 10 mm having a thickness of 4.35 mm is fabricated and its characteristics are studied. The DR is found to have a dielectric constant near to 5 and operates in the Wi Fi band of 5.25 GHz with a 2:1 VSWR bandwidth of 120 MHz.

Design of a compact printed lowpass filtering antenna with wideband harmonic suppression for automotive communication

This article presents a printed planar lowpass filtering monopole antenna with wide stopband for automotive communications. This monopole radiator exhibits hybrid geometry and is constructed using a circular slot and corner edged slot. The fundamental radiator's ground plane is defected to enhance the VSWR bandwidth and four rectangular patches with two open-circuit stubs is being used to construct a lowpass filter with wide stopband. The filtering characteristics are further improved by incorporating circular complementary split-ring resonator (CCSRR) on the ground plane. The proposed lowpass filtering antenna is obtained by integrating the lowpass filter with a super wideband (SWB) monopole antenna and experimentally validated with the measured reflection coefficient as <−10 dB in 0.67 to 4.15 GHz (69.25%). In this operating spectrum, the radiation pattern characteristics of the filtering antenna is identically stable and the passband average gain is >4.45 dBi. Further, the prototype filtering antenna bandwidth and radiation characteristics are analyzed in housing effects. The filtering antenna can be conveniently printed along with the existing printed circuit board or it can be located inside the shark fin housing thereby eliminating the need for a dedicated location in vehicular communications.