Wide Axial Ratio Bandwidth Research Articles

Inverted L-Shaped CP Patch Antenna with Corner-Truncated Partial Ground Plane Diagonally Adjoined with Square Branch for L-Band Applications.

This research proposes an inverted L-shaped patch antenna with a corner-truncated partial ground plane diagonally adjoined to a square branch for L-band applications. The adjoining square branch was used to perturb linear polarization for circular polarization, and the corner-truncated partial ground plane was utilized to enhance the axial ratio bandwidth (ARBW). Simulations were performed, an antenna prototype was fabricated, and experiments were carried out. The simulation and measured results were in good agreement. The proposed antenna could achieve an ARBW of 77.87% (1.09–2.48 GHz). The novelty of this research lies in the concurrent use of a square branch and a corner-truncated partial ground plane to realize wide ARBW in an L-band, rendering the technology suitable for satellite communication and navigation applications.

A Compact Helix Antenna With Wide Axial Ratio Bandwidth Using a Spiral Microstrip Coupling Feedline for GNSS Applications

A compact quadrangular prism-shaped slot helix antenna with wide axial ratio (AR) bandwidth using a spiral microstrip coupling feedline is presented. The proposed antenna is constructed with FR4 substrate copper-clad plate with four slots symmetrically etched on the substrate exterior surface and a spiral microstrip coupling feedline printed on the substrate inner surface. The electric field and equivalent magnetic current excited by the spiral microstrip feedline in slots are analyzed. The wide AR bandwidth is obtained. The proposed antenna has a small dimension of 0.156λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.156 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.182 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> (λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the free-space wavelength at the center frequency). Its measured -10 dB |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | bandwidths and 3 dB AR bandwidths are 1525-1662 and 1497-1630 MHz, respectively. It generates right-hand circular polarization (RHCP) without a complicated feeding network. It promises a good use in Global Navigation Satellite Systems.

A Travelling-Wave-Fed Slot Spiral Antenna With Wide Axial-Ratio Bandwidth and Beamwidth for GNSS Applications

A travelling-wave-fed slot spiral antenna with wide axial-ratio (AR) bandwidth and beamwidth for GNSS applications is proposed in this paper. The evolution procedure of the proposed antenna can be classified into three steps. Firstly, 12 identical spiral slots are arranged concentrically in a compact area, and AR roundness in low elevation plane is improved by virtue of good rotational symmetry of slot radiators. Secondly, a two-turn travelling-wave feed line is sequentially coupled to the slots, and wideband response of desired magnitude ratio and phase difference of $E_{\theta }$ and $E_{\varphi }$ is obtained by optimizing the number and growth rate of microstrip turns. Thirdly, by supporting the antenna with a modified metallic cavity, the CP radiation performance in low elevation plane is well improved, and thus a widened AR beamwidth is obtained. Finally, the proposed antenna with satisfactory performance is realized in a diameter of $0.56\lambda _{0}$ and height of $0.12\lambda _{0}$ , where $\lambda _{0}$ is the free-space wavelength at center frequency 1.4 GHz. Measured bandwidth of $|S_{11}|$ fully covers the entire GNSS bands, and the 3-dB AR bandwidth ranges from 1.14 to 1.67 GHz (37.7%). Moreover, the 3-dB AR beamwidth exceeds 140° at 1.4 GHz.

Design of a Wideband Dual-Feed Circularly Polarized Antenna for Different Axial Ratio Requirements

A novel method of designing a wideband dual-feed circularly polarized (CP) antenna is presented for different axial ratio (AR) requirements. By analyzing the output characteristic of the feed network for the dual-feed CP antenna, an approximate function is obtained and utilized to calculate the variances of the output magnitude and phase of the feed network under a required AR. Based on the analysis, different branch-line couplers are used for achieving wide AR bandwidths of less than 3, 2, and 1 dB, respectively. Compared to the traditionally used 3 dB coupler, the presented feed method can have an AR peak with the expected value at the center frequency and two AR valleys beside the peak, while the traditional 3 dB coupler can only get an AR valley with narrower bandwidth. Therefore, much wider AR bandwidths for different AR requirements are obtained by using the presented method. The wideband dual-feed antenna fed by these different couplers was simulated, fabricated, and measured for the final performance verification.

Wideband Circularly Polarized Cylindrical Dielectric Resonator Antennas With Rectangular Curved Slots [Antenna Applications Corner

Wideband circularly polarized antennas with wide axial-ratio (AR) bandwidth and required gain are desired for point-to-multipoint communication and remote tracking applications. Two different designs of probe-fed rectangular curved slotted dielectric resonator antenna (SDRA) models are proposed in this article, one with an overall size of 50 × 50 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (SDRA-1) and the other a scaled-down version with 25 × 25 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (SDRA-2). Axially symmetric rectangular curved slots are introduced in cylindrical dielectric resonator antennas (CDRAs) to create asymmetry in the structure for circular polarization (CP). The proposed SDRA-1 offers a wide impedance bandwidth of 55% (4.14-7.31 GHz) and a 3-dB AR bandwidth of 38% (4.82-7.07 GHz) with a minimum AR value of 0.1 dB. The peak gain obtained for SDRA-1 is 6 dBi. A scaled-down version of the dielectric resonator antenna (DRA) provides an impedance bandwidth of 57.5% (7.34-12.94 GHz), a 3-dB AR bandwidth of 0.76 GHz, and a peak gain of 5.52 dBi. The proposed DRA models are suitable for IEEE wireless standard 802.11ac Wi-Fi (5 GHz), IEEE 802.11a (5.2 GHz), IEEE 802.16d worldwide interoperability for microwave access (WiMax) and x-band applications.

Wideband Circularly Polarized Magnetoelectric Dipole Array Using TE340-Mode Cavity and Sequential Rotation Feed-Network at 60 GHz

In this paper, a 4 × 4 60-GHz circularly polarized (CP) magnetoelectric (ME) dipole array based on TE340-mode substrate integrated cavity (SIC) and sequential rotation feed-network (SRFN) is proposed. The ME dipole array is constructed by 3 printed circuit board (PCB) layers with its assembled size of 21 × 23 × 2.4 mm3. The top layer is the radiation layer with 2 × 2 subarrays. The second layer includes 2 × 2 TE340-mode SICs. The bottom layer is the substrate integrated waveguide (SIW)-SRFN. By combining ME dipole, SRFN and high-order-mode SIC techniques, a compact 4 × 4 array with wide axial-ratio (AR) and impedance bandwidths is obtained. The measured results show that the − 10-dB impedance bandwidth is 24% (54–68.7 GHz), the 3-dB AR bandwidth is 25.9% (52–67.5 GHz), the 3-dB gain bandwidth is 22.5% (54–67.5 GHz) and the peak gain is 19.4 dBic at 62 GHz. The proposed array is a good candidate for 60 GHz wireless communications with its advantages of compact size, wide impedance bandwidth, wide AR bandwidth and high gain.

3-D-Printed Circularly Polarized Twisted-Ridge Horn Antenna

A novel wideband circularly polarized (CP) horn antenna with a pair of twisted ridges is investigated in this communication. The wide impedance bandwidth is obtained by adapting a pair of exponential-shaped ridges, whereas the wide axial ratio (AR) bandwidth is achieved by twisting the ridges. The impedance matching and AR can be tuned easily and independently, which is an attractive feature of the design. An $X$ -band right-hand circular polarization (RHCP) design was simulated with CST Microwave Studio. Its metal-printed prototype was fabricated to validate the simulation. The measured 15 dB impedance and 3 dB AR bandwidths are 53% (7.43-12.80 GHz) and 65% (7.63-15.00 GHz), respectively, with an overlapping bandwidth of 51% (7.63-12.80 GHz). The measured peak antenna gain is between 8.0 and 10.1 dBic in the operating band.

Single-Fed Broadband CP Bidirectional Antenna with Double-Layer Diagonally Aligned Plates for Universal UHF-RFID Applications

This research proposes a single-fed broadband circularly polarized (CP) bidirectional antenna operable in 840–960 MHz frequency band for readers of universal UHF-RFID applications. The proposed antenna is comprised of upper-layer conductor, lower-layer conductor, and wall patches. The upper-layer conductor consists of two diagonally aligned rectangular copper plates with a feeding gap at the center, and the lower-layer conductor is of two diagonally adjoined rectangular plates. The upper- and lower-layer conductors are adjoined with the wall patches. The diagonal alignment technique of the upper- and lower-layer plates was used to realize circular polarization and improve 3-dB axial ratio (AR) bandwidth. The double layers were deployed to improve impedance bandwidth (|S11| &lt; −10 dB) and achieve bidirectional radiation pattern. The simulated impedance bandwidth and 3-dB AR bandwidth were 772.19–1014.6 MHz (27.13%) and 675–1000 MHz (38.80%), and the corresponding measured results were 759–1011 MHz (28.47%) and 648–1110 MHz (52.55%). The simulated LHCP/RHCP half-power beamwidth (HPBW), 3-dB AR beamwidth, and gain were 56° – 90°/54° – 92°, 60° – 104°, and 4.94 – 5.89 dBic, while the corresponding measured results were 52° – 98°/62° – 97°, 96° – 126°, and 4.28 – 5.72 dBic. As a result, the single-fed broadband CP bidirectional antenna is applicable to universal UHF-RFID readers. Besides, the novelty of this research lies in the use of diagonal alignment of conducting plates to achieve circular polarization and wider AR bandwidth.

Dual Circularly Polarized Planar Four-Port MIMO Antenna with Wide Axial-Ratio Bandwidth.

A broadband compact-sized planar four-port multiple-input–multiple-output (MIMO) antenna with polarization diversity is presented. The proposed dual circularly polarized (CP) MIMO antenna consists of four G-shaped monopole elements, two of which are left-hand CP and the other two are right-hand CP. A vertical line strip in the G-shaped radiating element acts in balancing the vertical and horizontal electric field components to obtain 90° phase difference between them for circular polarization. Also, an I-shaped strip is incorporated between the ground planes of the G-shaped antenna elements to obtain equal voltage level in the proposed MIMO configuration. The dual circular polarization mechanism of the proposed MIMO/diversity antenna is analysed from the vector current distributions. The impedance bandwidth (S11 ≤ –10 dB) of the MIMO antenna is 105.9% (4–13 GHz) and the 3 dB axial ratio bandwidth (ARBW) is 67.7% (4.2–8.5 GHz), which is suitable for C-band applications. The overall size of the MIMO antenna is 70 × 68 × 1.6 mm3, and the minimum isolation between the resonating elements is 18 dB. The envelope correlation coefficient is less than 0.25, and the peak gain within the resonating band is 6.4 dBi.

Use of non‐uniform RIS and parasitic strips to improve antenna CP performance

The effect of using a non-uniform reactive impedance surface (RIS) on the circular polarisation performance of a planar antenna is investigated. It is shown that a very wide axial ratio (AR) bandwidth can be obtained, especially when the RIS is combined with parasitic strips. This result is only possible, thanks to the fact that the RIS is non-uniform. The technique is demonstrated by designing, building, and measuring a prototype. The simulated impedance bandwidth S 11 ≤ − 10 dB is 43.6% (4.3–6.7 GHz), and the simulated 3 dB AR bandwidth is 37.2% (4.6–6.7 GHz). The gain variation over the 3 dB AR bandwidth is 3–5.9 dBi. The experimental results are in good agreement with the simulations, validating the new concept.

Wide axial-ratio bandwidth crossed dipole RFID antenna

AbstractA circularly polarised RFID tag antenna with wide axial ratio bandwidth, wide impedance bandwidth and simple tuning network is presented. The antenna, based on the widely used crossed-dipole design, incorporates a novel matching network based on two large L-shaped strips joining the arms of the dipoles to match the impedance. The L-shaped strips create large area loops enabling the antenna to be adapted to the high inductances required for good matching without the currents flowing through them degrading the axial ratio of the antenna. The gain pattern, input impedance and axial ratio (AR) are computed with numerical simulation and measurements, resulting in a 30 MHz bandwidth based on the −3 dB Axial Ratio criterion, which can provide a maximum reading distance of 12.8 m.

Wideband Low-Profile Circularly Polarized Patch Antenna Using 90° Modified Schiffman Phase Shifter and Meandering Microstrip Feed

This communication proposes a wideband low-profile circularly polarized patch antenna based on a broadband 900 modified Schiffman phase shifter and a meandering L-shaped microstrip feed. The whole antenna consists of a broadband hybrid feeding network and a circular patch radiator. The hybrid network has two branches that operate in the first and second Schiffman periods, and thus can achieve 113% 10 dB return loss bandwidth and 75% phase shift bandwidth within 900±4.60 under a relaxed coupling strength of 1.58. To reduce the profile, the planar microstrip L-shaped feeding probe is properly meandered, which provides not only broadband impedance matching, but also an extra degree of freedom in the reduction of cross polarization, thus achieving a wide axial ratio (AR) bandwidth. Simulated and measured results show that the antenna has indeed achieved a low profile (0.05 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ) with 50.5% impedance bandwidth, 47.8%AR bandwidth , and 34% gain bandwidth (>3 dBi).

Ultra-Miniature Circularly Polarized CPW-Fed Implantable Antenna Design and its Validation for Biotelemetry Applications

The paper presents a coplanar waveguide (CPW)-fed ultra-miniaturized patch antenna operating in Industrial, Scientific and Medical (ISM) band (2.4–2.5 GHz) for biotelemetry applications. The proposed antenna structure is circular in shape and its ground plane is loaded with a pair of slots for obtaining circular polarization. In the proposed design, asymmetric square slots generate phase condition for right-hand circularly polarized (RHCP) radiation. And, by merely changing the position of the slots, either RHCP or left-hand circularly polarized (LHCP) radiation can be excited. In the proposed design, a meandered central strip is used for miniaturization. The simulations of the proposed antenna are carried out using Ansys HFSS software with a single-layer and multilayer human tissue models. The antenna shows good performance for different tissue properties owing to its wide axial ratio bandwidth and impedance bandwidth. The antenna is fabricated and measurements are carried out in skin mimicking phantom and pork. Simulated and measured performances of the antenna are in close agreement. The power link budget is also calculated using an exterior circularly polarized (CP) receiving antenna.

Dual-Band Frequency Antenna for Drone Application

Dual-band antenna is the main element for this project of unmanned aerial vehicle application. Previously, a frequency of 2.45 GHz is informed of linear polarization while the frequency of 1.575 GHz informed of circular polarization. Global Positioning System (GPS) applied towards the UAV use circular polarization with the antenna facing up for satellite connection and for Industrial Scientific and medical (ISM), the UAV use linear polarization where the antenna is facing down towards the ground to establish a connection with others electronic devices. Integrating both antennas into single antenna unit is challenging as it involves the characteristics of dual-band of frequencies and dual types of polarization where all the characteristics need to be fulfilled as a whole in order to be functioned as dual-band dual polarization antenna. Computer simulation software (CST) is used to design and optimize the antennas. Comparison is done among four designs of antennas designs which use microstrip feed line and proximity coupled feed to obtain the most efficient design to be applied at UAV for full operation. The best technique covered in order to fulfill all the requirements needed is proximity coupled feed. Design four is the best design because of the wide axial ratio bandwidth and efficiency is high.

A Low-Profile Wideband Linear-To-Circular Polarization Conversion Slot Antenna Using Metasurface.

A new low-profile wideband linear-to-circular polarization conversion microstrip slot antenna based on a metasurface for C-band satellite communication applications is proposed in this paper. The metasurface basically consists of four unit cells with parasitic square cross gaps arranged in a 2 × 2 layout. By loading the metasurface on the microstrip slot antenna, linearly polarized (LP) waves from the source antenna are converted into circularly polarized (CP) waves. Then, by etching three more parasitic square cross gaps in the middle of the metasurface, enhanced impedance bandwidth and axial ratio bandwidth (ARBW) are achieved. Furthermore, an equivalent circuit and a phase analysis are presented to explain how a wide ARBW is realized by the metasurface. A final model with an overall size of 36 × 36 × 3.5 mm3 (approximately 0.65λ0 × 0.65λ0 × 0.06λ0 at 5.5 GHz) was designed and fabricated. The measured S11 bandwidth and 3 dB ARBW were 39.25% from 4.28 GHz to 6.37 GHz and 17.77% from 5.18 GHz to 6.19 GHz, respectively. As a result, the proposed antenna shows great potential for satellite communication applications due to its low profile and compact structure, wide impedance bandwidth, and wide axial ratio bandwidth.

Design of Quad-Port Ultra-Wideband Multiple-Input-Multiple-Output Antenna with Wide Axial-Ratio Bandwidth.

This article presents a compact, planar, quad-port ultra-wideband (UWB) multiple-input–multiple-output (MIMO) antenna with wide axial ratio bandwidth (ARBW). The proposed MIMO design consists of four identical square-shaped antenna elements, where each element is made up of a circular slotted ground plane and feed by a 50 Ω microstrip line. The circular polarization is achieved using a protruding hexagonal stub from the ground plane. The four elements of the MIMO antenna are placed orthogonally to each other to obtain high inter-element isolation. FR-4 dielectric substrate of size 45 × 45 × 1.6 mm3 is used for the antenna prototype, and a good agreement is noticed among the simulated and experimental results. The proposed MIMO antenna shows 3-dB ARBW of 52% (3.8–6.5 GHz) and impedance bandwidth (S11 ≤ −10 dB) of 144% (2.2–13.5 GHz).

Dual‐band dual‐polarized compact planar monopole antenna for wide axial ratio bandwidth application

In this article, a geometrically simple, microstrip line-fed planar monopole structure with slanting edge ground plane is designed to realize the dual-band dual-polarized operation. The proposed antenna consists of a rotated U-shaped patch and an electromagnetically coupled L-shaped parasitic radiating element. Owing to the combination of microstrip line-fed radiating patch and a slanting-edge rectangular ground plane on the opposite side of the substrate, the proposed dual-band antenna can generate broad axial ratio bandwidth (ARBW) in the upper frequency band. The overall dimension of the prototype is only 32 × 32 × 1.6 mm3. The measured results validate that the proposed antenna has two operational frequency bands, 29.84% (1.54-2.08 GHz) for linearly polarized radiation and 71.85% (3.96-8.4 GHz) for circularly polarized radiation. Measured result shows that 3-dB ARBW of the proposed antenna is 73.54% (3.80-8.22 GHz) in the higher frequency band. It shows that the higher frequency band exhibits a left-hand circularly polarized radiation in the boresight direction.

Broadband Circularly Polarized Rectenna With Wide Dynamic-Power-Range for Efficient Wireless Power Transfer

This paper presents a circularly polarized (CP) rectenna with the advantage of achieving high efficiency in both wide operating power and frequency ranges. The proposed rectenna is composed of a high-efficiency rectifier and broadband CP antenna. In the proposed rectifier, a novel wideband resistance compression technique is presented, highly improving the matching performance of the circuit in a wide range of input power and frequency. The technique is achieved by an impedance manipulation network and a coupled-lines-based resistance compression network (RCN). Theoretical analysis is carried out and closed-form equations are derived for the design of the rectifier. Simulated and measured results show that over 60% (up to 76%) conversion efficiency is achieved for the input power range of 5-17 dBm and frequency band of 1.7-2.9 GHz (mobile, Wi-Fi and ISM bands). Subsequently, unlike the conventional half-wavelength slot antenna, a compact CP antenna with a side length of quarter wavelength is designed by using a 1-wavelength loop slot and a coupled-line-based phase shifter. It has wide axial-ratio bandwidth and good radiation pattern. At last, by integrating the proposed rectifier together with the CP slot antenna, a broadband CP rectenna is completed with higher efficiency by about 18.6% than that without wideband RCN.

Compact broadband circularly polarized printed antenna with a shifted monopole and modified ground plane

This paper presents a new and compact printed monopole antenna with broadband circular polarization (CP). The wide axial ratio bandwidth is achieved by placing and feeding a monopole on the side of an FR4 dielectric. In addition, a conventional horizontal ground plane is modified by shortening its width and adding a vertical extension. Experimental results show an |S11| and axial ratio (AR) of 123.5% fractional bandwidth (2.6–11 GHz) and 70% fractional bandwidth (3–6.2 GHz), respectively. The presented antenna is compact with an area of 36 mm × 19.5 mm, simple to design and fabricate, and can achieve broadband AR without using: parasitic elements, and perturbations in terms of creating multiple slots and stubs.

Wideband High-Gain Circularly Polarized Antenna Using Artificial Anisotropic Polarizer

A novel wideband high-gain circularly polarized (CP) antenna is proposed and investigated for the 60 GHz high-throughput communication and the 77 GHz automobile radar system. The design consists of a rectangular horn, a hyperbolic lens, and an artificial anisotropic polarizer. To minimize the thickness of the polarizer, the properties of the artificial anisotropic material (AAM) for generating CP wave are discussed analytically. Minimal polarizer thickness and the corresponding component ratio are provided mathematically. In comparison with other approaches, the proposed design achieves a relatively high-gain and wideband performance with a minimal thickness. The antenna exhibits a wide impedance bandwidth of more than 39% (VSWR < 2) from 55 to 82 GHz and a wide axial ratio (AR) bandwidth of more than 32% (AR < 3 dB) from 56 to 77 GHz. The average gain is 17 dBic. Good unidirectional radiation characteristics are achieved with low fabrication cost. In addition, the off-body lens and the polarizer could be directly migrated to other radiating sources with the concrete analytical guidance for polarizer design.