Wide Axial Ratio Beamwidth Research Articles

Wideband Circularly Polarized Antenna With Dual-Mode Operation

This letter presents a simple structure of a single-fed broadband circularly polarized (CP) antenna. The antenna consists of four L-shaped strips that rotate in sequence and a double vacant-quarter ring. The double vacant-quarter ring primarily contributes to the wide axial-ratio bandwidth, while the L-shaped strip primarily contributes to the wide axial-ratio beamwidth, with the two modes combined to achieve a wideband CP operation. A prototype antenna was designed, fabricated, and measured. The measured results show that the proposed antenna yields a 10 dB impedance bandwidth of 92.8 $\%$ (4.5–12.3 GHz), a 3 dB axial-ratio bandwidth of 67.5 $\%$ (5.3–10.7 GHz), and a 3 dB gain bandwidth of 62.3 $\%$ (5.3–10.1 GHz) with a peak gain of 12.4 dBic.

An Ultra-Wideband Circularly Polarized Asymmetric-$S$ Antenna With Enhanced Bandwidth and Beamwidth Performance

This paper introduces an ultra-wideband circularly polarized (CP) asymmetric-S antenna with wide axial ratio beamwidth (ARBW) for C-band applications. The proposed antenna is realized by bending a linearly polarized dipole into asymmetric-S shape with variable trace width, which achieves CP radiation. Unlike the reported symmetric-S antenna, the proposed antenna is constituted with two unequal curved arms to enhance the bandwidth and beamwidth performances. Compared with the symmetric-S antenna, the proposed antenna demonstrates much wider AR bandwidth and wider ARBW over broader frequency range. A prototype is fabricated to verify the design principle. The measured and simulated results are very consistent and both indicate that the proposed antenna has a wide impedance bandwidth (VSWR <; 2) of 70.2% (3.58 to 7.46 GHz), and a wide 3-dB AR bandwidth of 84.8% (2.75 to 6.8 GHz). Moreover, maximum ARBW of 153° is achieved, and a 3-dB ARBW of more than 100° is maintained within a wide operation bandwidth of 46.3% (3.65-5.85 GHz).

A Low-Profile Wideband Circularly Polarized Crossed-Dipole Antenna With Wide Axial-Ratio and Gain Beamwidths

A low-profile wideband circularly polarized (CP) crossed-dipole antenna that has both wide axial-ratio beamwidth (ARBW) and half-power beamwidth (HPBW) is presented in this paper. The crossed dipoles are composed of four trapezoidal patch arms, and they are fed by a pair of vacant-quarter printed rings to generate CP radiation. Four identical parasitic elements that consist of a horizontal triangle patch and a vertical metallic plate are symmetrically intervened between the crossed dipoles and the ground plane. It has been found that the parasitic elements can effectively decrease the antenna profile, increase the operating bandwidth, and simultaneously enhance the ARBW as well as the HPBW. A prototype was fabricated and measured to verify the design. The measured results show that the prototype has a low profile of $0.1\lambda _{0}$ , a −10 dB impedance bandwidth of 78.3% and a 3 dB AR bandwidth of 63.4%. Moreover, a 3 dB ARBW of more than 120° and an HPBW of more than 110° are achieved simultaneously within a wide passband of 50.7%.

A low profile circularly polarized antenna with L-shape energy coupling slot and the S-shaped matched transmission line

ABSTRACTIn this paper, a novel low profile circularly polarized antenna with L-shape energy coupling slot and the S-shaped matched transmission line (SMTL) is presented. It consists of a monopolar radiator and a hexagonal radiator which will generate vertically and horizontally polarized electric field Eθ and Eφ, respectively. To satisfy the required magnitude/phase relationship between two radiators, the double L-shape energy coupling slot and the SMTL are introduced. Also, 12 circular shape patches are arranged sequentially on the hexagonal radiator to obtain a wide AR beamwidth. The measured results show that the realized antenna has an impedance bandwidth of 2.1% (5.76–5.88 GHz). In particular, the 3 dB Axial Ratio (AR) beamwidth at 5.8 GHz is extended to 212° (φ = 0° plane) and 217° (φ = 90° plane). Stable RHCP omni-directional radiation patterns are obtained over the operating bandwidth with a peak gain of 1.25 dBi. A good agreement between the simulated and measured results is obtained.

Compact Circularly Polarized Patch Antenna With Wide Axial-Ratio Beamwidth

This letter presents a compact circularly polarized patch antenna with wide axial-ratio (AR) beamwidth. The simulation reveals that by etching two pairs of asymmetric slots on the patch and loading coupled strips, the phase differences between the radiated orthogonal fields become flatter and maintain approximately at 90° over a wide angular range; hence, a wide AR beamwidth is achieved. Experimental results agree well with the simulation results. Particularly, this antenna achieves a wide AR beamwidth of 188° in both the principal and diagonal planes.

Single-Fed Wide-Beamwidth Circularly Polarized Patch Antenna Using Dual-Function 3-D Printed Substrate

This letter presents a novel single-fed microstrip patch antenna using three-dimensional (3-D) printed substrate for both circular polarization and wide 3 dB axial-ratio beamwidth (ARBW). Here, the substrate consisting of a photosensitive resin and air with a square mesh-grid structure is dual-function. On the one hand, the permittivity of the substrate in two orthogonal directions is tuned to be slightly different by inserting two resin chunks. Hence, the asymmetry of the substrate can split the two degenerate modes of the patch antenna so as to generate circularly polarized waves. On the other hand, the effective permittivity of the substrate can be freely controlled by the volume fraction of air, and thus influences the 3 dB ARBW. As a result, wide ARBW can be realized by properly configuring substrate through a 3-D printing process. A prototype is fabricated and measured. Measured results are found in reasonably good agreement with the simulated ones, exhibiting a 3 dB ARBW as wide as 120°.

An omni-directional circularly polarized antenna with a low profile and wide axial-ratio beamwidth

ABSTRACTA novel low profile omni-directional circularly polarized (CP) antenna with wide axial-ratio (AR) beamwidth in the elevation plane is proposed. It is composed of a compound vortex radiator, a ground plane, and two groups of vias. By adjusting the structure of the compound vortex stub, |Eθ| = |Eφ| is realized in a wider range of θ. Also, the 90° phase difference between Eθ and Eφ is obtained by regulating the size of a sector patch at the end of the vortex stub. The measured results show that the proposed antenna has an impedance bandwidth of 3.2% (3.03–3.13 GHz) and a 3 dB AR bandwidth of 21.6% (2.5–3.17 GHz). Also, the 3 dB AR beamwidths at 3.10 GHz are 270° and 274° in the φ = 0° and φ = 90° planes, respectively. A good agreement between the simulated and measured results is obtained.

Pin‐loaded circularly‐polarised patch antenna with sharpened gain roll‐off rate and widened 3‐dB axial ratio beamwidth

A circularly-polarised patch antenna with the loading of shorting pins is proposed in this study to sharpen the gain roll-off shape and widen the 3-dB axial ratio beamwidth (ARBW). First of all, it is theoretically revealed that when the electrical size of a circular patch radiator is appropriately constituted, the radiation gain at the horizon can be significantly suppressed and the axial ratio can be maintained below 3 dB over a wide angular range. By introducing a set of metallic pins, which short the patch in a circular contour, the resonant frequency of the antenna will be increased. In this way, the patch radius with respect to wavelength can be freely chosen, so that sharp gain roll-off rate and wide ARBW can be simultaneously achieved. After the extensive analysis is executed, two circular patch antennas with and without loading of shorting pins are designed, fabricated and tested for comparison. Simulated and measured results show that the gain roll-off is enhanced up to near 20 dB and 3-dB ARBW is extended to around 140° so as to effectively reduce the undesired multipath interference as highly demanded in the application of global navigation satellite system.

Cavity‐backed self‐phased circularly polarized antenna based on stepped‐width dipole with wide axial ratio beamwidth

AbstractA cavity‐backed self‐phased circularly polarized (CP) antenna based on stepped‐width dipoles with wide axial ratio beamwidth is proposed for global positioning system (GPS) applications. The radiator of the antenna consists of two pairs of stepped‐width dipoles, contributing to the CP radiation. The working principle of CP radiation is elaborated by using two simplified models. Then, a feeding network consisting of a Y‐shaped structure and two pairs of identical coplanar striplines (CPSs) is utilized to feed the radiator. Moreover, a cavity‐backed reflector is employed in this antenna to achieve a unidirectional radiation with wide axial ratio (AR) beamwidth. Measured results show that the proposed antenna achieves a wide impedance bandwidth of 43% from 1.37 to 2.12 GHz with Return Loss &gt; 15 dB, and a 3‐dB axial ratio (AR) bandwidth of 6.98% from 1.52 to 1.63 GHz. Particularly, the antenna shows a right‐hand circular polarization (RHCP) radiation with wide 3‐dB AR beamwidth of 205° and 215° in the XOZ and YOZ plane at the center frequency of 1.575 GHz, respectively.

Inverted-S Antenna With Wideband Circular Polarization and Wide Axial Ratio Beamwidth

A novel broadband circularly polarized (CP) antenna with wide axial ratio (AR) beamwidth is proposed. It is composed of two curved arms shaped like an inverted “S.” The mechanisms of wideband CP operation and wide AR beamwidth are explained. To validate the concept, a prototype at C-band is manufactured and measured. Experimental results confirm that the antenna achieves an impedance bandwidth of 63% and a CP bandwidth of 42%. Furthermore, maximum AR beamwidth of 140° is achieved and wide AR beamwidth can be maintained in a frequency bandwidth of 35% in nearly all elevation planes. In addition, the antenna has the advantage of being easily extended to arrays. A four-element array using the proposed antenna is investigated through both simulations and experiments, and achieves 60% CP bandwidth and wide AR beamwidth. The proposed inverted-S antenna can realize wide CP bandwidth and wide AR beamwidth, and can easily form wideband CP arrays.

Circularly Polarized Substrate Integrated Waveguide Antenna With Wide Axial-Ratio Beamwidth

A circularly polarized (CP) substrate integrated waveguide (SIW) antenna is presented. First, our study demonstrates that wide axial-ratio beamwidth can be achieved by exciting a square slot with four pins. Second, gap rings are employed around the pins to control the resonant frequency of the antenna. After the variation of thee diameters of gap rings, the frequency of best impedance match corresponds to that of the widest axial-ratio beamwidth. Finally, a CP antenna is designed and fabricated. Experimental results are found in good agreement with simulations in terms of radiation patterns, gain, axial ratio, and reflection coefficient. In particular, the 3-dB axial-ratio beamwidth at the center frequency of 7.98 GHz is extended to 150°.

Cavity-Backed Self-Phased Circularly Polarized Multidipole Antenna With Wide Axial-Ratio Beamwidth

A cavity-backed, self-phased, circularly polarized (CP) antenna with a wide beamwidth based on multidipole is proposed for global positioning system applications. The radiator of this antenna consists of a pair of longer dipoles and a pair of shorter dipoles, which contribute to the CP radiation. A cavity-backed reflector is employed to achieve a unidirectional pattern with a wide axial-ratio (AR) beamwidth, high gain, and high front-to-back ratio (FBR). Measurements show that the proposed antenna achieves a wide impedance bandwidth of 52.4% from 1.24 to 2.12 GHz with a return loss of more than 15 dB and a 3-dB AR bandwidth of 7.55% from 1.53 to 1.65 GHz. Furthermore, a high FBR of more than 27.3 dB and a high gain of 7.7 ± 0.3 dBi are achieved within the 3-dB AR bandwidth. In particular, the antenna also shows a right-hand circular polarization radiation with extremely wide 3-dB AR beamwidth of 254° and 245° in the xoz - and yoz -planes at the center frequency of 1.58 GHz, respectively.

A printed wide-beamwidth circularly polarized antenna via two pairs of radiating slots placed in a square contour

A low-profile circularly polarized (CP) slot antenna to achieve a wide axial-ratio (AR) beamwidth is proposed in this paper. The radiating patch consists of two orthogonal pairs of parallel slots etched symmetrically onto a ground plane. Firstly, our theoretical study demonstrates that the CP radiation can be satisfactorily achieved at the broadside, when the vertical and horizontal paired-slots are excited in the same amplitude with 90° phase difference. Secondly, the principle of CP radiation of the proposed antenna on an infinite ground plane is described. Through analyzing the spacing between two parallel slots, the |Eθ| and |Eφ| radiation patterns can be made approximately identical with each other over a large angle range. As such, the slot antenna achieves a wide AR beamwidth. After that, the 3 dB AR beamwidth with respect to the size of a finite ground plane is investigated to constitute a practical CP antenna on a finite ground plane. In final, the proposed CP antenna with a 1–4 probe-to-microstrip feeding network is designed and fabricated on a finite ground plane of a dielectric substrate. Measured results are shown to be in good agreement with the simulated ones about the gain, reflection coefficient, AR bandwidth, and radiation patterns. Most importantly, a wide 3 dB AR beamwidth of 126° and low-profile property with the height of 0.036λ0 are achieved.

Low‐profile wide‐beamwidth circularly‐polarised patch antenna on a suspended substrate

A low-profile circularly-polarised (CP) patch antenna with wide axial-ratio (AR) beamwidth is proposed. Based on the transmission-line model, the radiation patterns of a CP patch antenna are calculated by modelling the entire patch as two pairs of equivalent parallel slots. Initially, the mechanism of wide-beamwidth CP radiation pattern is investigated. The results show that the | E θ | and | E φ | radiation patterns can be made nearly equalized over a large angular range, if the spacing L between two parallel slots is selected as 0.45 λ 0 (Condition I). For a square patch, the length of each slot must be equal to the spacing L , and it needs to be maintained as one half wavelength at resonance for radiation (Condition II). By using a suspended dielectric substrate, the two above conditions is simultaneously satisfied, resulting to achieve a wide AR beamwidth. After that, the effect of the finite ground size on the 3-dB AR beamwidth is analysed to constitute a practical CP antenna. Finally, the proposed CP antenna is designed and fabricated. Experimental results are in good agreement with the simulated ones in terms of radiation beamwidth, reflection coefficient and AR bandwidth. Practically, the antenna achieves a wide 3-dB AR beamwidth of 120°.

Millimeter-Wave Circularly Polarized Tapered-Elliptical Cavity Antenna With Wide Axial-Ratio Beamwidth

A millimeter-wave (mm-wave) circularly polarized (CP) antenna with wide axial-ratio (AR) beamwidth, consisting of L-shaped patches (LSPs) and a tapered elliptical cavity (TEC), is presented. The LSPs are fed by a transverse slot on the top metal surface of a substrate integrated waveguide, to excite two orthogonal modes in the cavity for CP radiation. Experimental results show that the proposed antenna can achieve a bandwidth from 56.9 to 63.4 GHz for both axial ratio≤ 3 dB and reflection coefficient |S11|≤ - 10 dB, and an average broadside gain of 10.4 dBi. In particular, the measured 3-dB AR beamwidths (ARBWs) at 60 GHz in the two orthogonal elevation planes have been extended to 134° in an angular range from -74° to 60°. The measured results agree reasonably with the simulated ones.

Wideband Circular Polarization Reconfigurable Antenna

This communication introduces a polarization reconfigurable wideband circularly polarized (CP) antenna, which consists of four radiating arms connected to a reconfigurable feeding network. The four radiating arms excited by the feeding network are able to generate wideband CP waves with bidirectional radiation patterns in free space. In order to increase the gain and obtain a broadside radiation pattern, the proposed antenna is placed above a metallic reflector with the distance of quarter wavelength at the center frequency. In addition, polarization reconfigurability is realized by utilizing PIN diodes in the feeding transmission lines such that left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP) modes can be selectively excited by controlling the on / off states of the PIN diodes. The proposed antenna exhibits a wide impedance bandwidth of 80% and an overlapped axial ratio (AR) bandwidth of 23.5% for both modes. The antenna gain is stable across the operating bandwidth with the peak gain of 4.8 dBic. The antenna has a wide AR beamwidth of 90°. The presented work is suitable for GPS, CNSS, or RFID applications.

A Miniaturized Wide-Beamwidth Circularly Polarized Planar Antenna via Two Pairs of Folded Dipoles in a Square Contour

A circularly polarized (CP) antenna with a wide axial-ratio (AR) beamwidth is presented by placing the two pairs of folded dipoles in a square contour. First, our study demonstrates that the CP radiation can be achieved at the broadside by setting a 90° phase difference between the vertical- and horizontal-paired folded dipole radiators. Second, a radiation pattern subtraction approach is presented to explain how the radiation beamwidth of the paired folded dipoles could be appropriately widened or narrowed according to the radiation pattern subtraction of two opposite electric current densities in the folded dipoles. Using this approach, the E-plane beamwidth of a pair of folded dipoles is made certainly widened, whereas its H-plane counterpart becomes narrowed. On this basis, the E- and H-plane radiation patterns can still be made approximately identical with each other over a wide range of polar angle, even though the distance between dipoles is deliberately shortened. As such, the desired CP antenna with shortened dipole-to-dipole distance and unaffected wide AR beamwidth can be achieved using two pairs of parallel folded dipoles with shortened distance between them instead of linear dipoles in [24] . Finally, a CP printed antenna is designed and fabricated on a single dielectric substrate. Experimental results are found in good agreement with the simulated ones in terms of radiation patterns, gain, AR, efficiency, and reflection coefficient. In particular, the 3-dB AR beamwidth at the central frequency of 1.6 GHz is extended to 135° at $XZ$ -plane and 142° at $YZ$ -plane. Moreover, the overall size of the constituted CP antenna with folded dipoles is decreased to $\mathbf{0}.\mathbf{43}\;{\boldsymbol{\lambda }_\mathbf{0}} \times 0.43\;{\boldsymbol{\lambda }_\mathbf{0}}$ ( ${\mathbf{\lambda }_\mathbf{0}}$ is the wavelength in free space).

A Low-Profile Wide-Beamwidth Circularly-Polarized Antenna via Two Pairs of Parallel Dipoles in a Square Contour

A circularly polarized antenna with wide axial-ratio beamwidth is presented by placing two pairs of parallel dipoles in a square contour. Firstly, our study demonstrates that circular polarization can be achieved at the broadside by setting a 90° phase difference between the vertical and horizontal paired-dipoles. Secondly, the principle of wide-beamwidth circularly-polarized radiation is described under the similarity in polar and azimuthal radiation pattern for a pair of parallel dipoles. After the spacing between two parallel dipoles is studied, the similar radiation patterns in these two orthogonal planes are derived. As such, a wide-beamwidth circular polarization can be achieved by placing the two pairs of parallel dipoles vertically and horizontally while setting a 90° phase difference between them. In final, a circularly-polarized printed antenna is designed and fabricated on a single dielectric substrate. The two arms of its four dipoles are formed on the lower and upper interfaces of the substrate, and they are excited by a 1-to-4 probe-to-microstrip feeding network. Experimental results show good agreement with simulated ones in terms of radiation pattern/gain, axial ratio and returned loss. In particular, the 3-dB axial ratio beamwidth at the central frequency of 1.6 GHz has extended to 126 ° in an angular range from -63° to +63°. The fabricated antenna exhibits a low-profile property with the height of 0.0043 free-space wavelength.

A CIRCULARLY-POLARIZED METASURFACED DIPOLE ANTENNA WITH WIDE AXIAL-RATIO BEAMWIDTH AND RCS REDUCTION FUNCTIONS

A new circularly-polarized metasurfaced dipole antenna (MSDA) with wide axial-ratio (AR) beamwidth and radar cross section (RCS) reduction properties is proposed and studied in this paper. This antenna is a quite simple half-wavelength linear dipole right above a metasurface which consists of 9 double-head arrow-shaped unit cells arranged in a 3×3 layout. By cautiously choosing the geometrical parameters of the metasurface and tuning the distance between the dipole and the metasurface, the whole structure turns out to be a circularly-polarized antenna with RCS reduction feature. Simulation results show that the MSDA in circular polarization achieves an operating bandwidth of 410MHz and a wide AR beamwidth of 123◦ and 90◦ in φ = 0◦ and φ = 90◦ planes respectively, together with a maximum RCS reduction of 10.4 dB in the whole operating band.

Crossed Dipole Loaded With Magneto-Electric Dipole for Wideband and Wide-Beam Circularly Polarized Radiation

A crossed dipole that is loaded with a magneto-electric dipole to produce the wideband and wide-beam circularly polarized radiation characteristics is proposed. The crossed dipole is incorporated with double-printed vacant-quarter rings to feed the antenna. The antenna is backed by a metallic cavity to provide a unidirectional radiation pattern with a wide axial-ratio (AR) beamwidth and a high front-to-back ratio. Experimental results showed that the prototype with an overall size of $120\times 120\times30.5~\hbox{mm}^3$ has a $\vert { S}_{11}\vert bandwidth of 1.274–2.360 GHz and a 3-dB AR bandwidth of 1.39–1.82 GHz. The antenna showed a right-hand circular polarization (CP) radiation with a very wide 3-dB AR beamwidth ( $>165^{\circ}$ ) and a high radiation efficiency ( $ > 94\%$ ) within the operational bandwidth.