Broadband Circularly Polarized Radiation Research Articles

A Compact Circularly Polarized Crossed Dipole Antenna with Wide Bandwidth using Split Ring Resonator and Parasitic Patches

A new compact broadband circularly polarized (CP) crossed dipole antenna using split ring resonator (SRR) and parasitic patches are presented. The proposed antenna is mainly composed of two orthogonal strip dipoles, two 90∘ phase delay lines, four SRRs, and four parasitic patches. The combination of the orthogonal strip dipoles and the delay lines forms a crossed dipole as the main CP radiator. The well-designed SRR can extend the current path and improve the current distribution of high-frequency without increasing the size of the antenna, thereby reducing the size of the antenna and increasing the axial ratio (AR) bandwidth of the high-frequency. The introduction of parasitic patches can improve the current distribution between the upper and lower cut-off frequency points of the bandwidth, and make up for the defects of the insufficient bandwidth of the crossed dipole and the SRR, thereby realizing broadband CP radiation. To verify the antenna, a physical prototype is fabricated. The measured results show that the impedance bandwidth (IBW) of 69.1% (1.38-2.84 GHz), and a wide AR bandwidth of 57.7% (1.43-2.59 GHz). In addition, the designed antenna achieves a stable gain in the working band and a certain band-edge selectivity. Such a single-fed, simple structure and the wideband CP antenna is an excellent candidate for communication systems such as ISM (2.4 GHz), WiBro (2.3-2.39 GHz)and Inmarsat.

A low-profile broadband crossed-dipole antenna with fractal structure and inverted-L plates

A low-profile broadband circularly polarized (CP) crossed-dipole antenna is proposed. In this antenna, the dipole uses a fractal-based structure with multiple similar patches for obtaining broadband CP radiation and impedance matching. The incorporation of the crossed-dipole antenna with four triangular parasitic patches improves both the impedance and axial ratio (AR) bandwidths. Four parasitic coupled inverted-L metal plates are loaded on the ground plane to significantly enhance the AR bandwidth and reduce the antenna profile. The measured results are in agreement with the simulations, which demonstrates that the proposed antenna has a low profile of 0.18 λ0, a − 10 dB impedance bandwidth of 91% (2.78–7.42 GHz), a 3 dB AR bandwidth of 81.5% (2.99–7.1 GHz), and a good right hand circular polarization (RHCP) radiation pattern with an average gain of 7.9 dBi over the whole operating band.

Broadband Dual Circularly Polarized Dielectric Resonator Antenna for Ambient Electromagnetic Energy Harvesting

For the application of ambient electromagnetic energy harvesting, it is important to collect as much electromagnetic energy as possible in broadband and with arbitrary polarizations. Meanwhile, the antenna should also have high receiving efficiency in order to effectively convert the collected energy into radio frequency current. To meet this requirement, a novel broadband dual circularly polarized (CP) dielectric resonator antenna (DRA) with high receiving efficiency is proposed. The characteristic mode analysis (CMA) is applied to analyze the proposed DRA to reveal the intrinsic behavior of the DR, so that proper mode excitations can be guided. It is found that broadband CP radiation is achieved by exciting two pairs of orthogonal degeneration modes. By choosing a broadband feeding structure, a broadband DRA can be obtained. When different ports are excited, left-hand CP (LHCP) or right-hand CP (RHCP) field can be generated. Measurements show that the antenna has a 3 dB axial-ratio (AR) bandwidth of 43.5%. The impedance bandwidth is wide enough to cover the whole AR bandwidth. The receiving efficiency of the proposed antenna is about 85% within most of the operating frequency range. With these appealing features, the proposed DRA is an excellent candidate for ambient electromagnetic energy harvesting.

Broadband Circularly Polarized Cross-Dipole Antenna With Multiple Modes

A broadband circularly polarized (CP) cross-dipole antenna with multiple modes is proposed. The antenna is composed of two pairs of crossed strip dipoles as driven elements, four square-slot patches, and four corner-truncated patches as parasitic elements. A pair of vacant-quarter printed rings is used as sequential phase feeding structure to generate a CP mode, which connect to crossed strip dipoles. By using these coupled rotated elements, multiple CP modes can be stimulated to satisfy the need of broadband CP radiation. In addition, four shorted square metal columns are also introduced in the antenna design to generate an additional CP resonance. A verified prototype was fabricated and measured in this paper. The measured results demonstrate the proposed antenna features wideband CP characteristics with a wide impedance bandwidth (IBW) of 95.5% (0.92-2.60 GHz) and a broad axial-ratio bandwidth (ARBW) of 94.4% (0.95-2.65 GHz).

Broadband Circularly Polarized Antenna With Non-Planar Reflector

In this article, a compact broadband circularly polarized (CP) antenna with non-planar reflector is presented. In this antenna, two fan-shaped cross-dipoles as the primary radiator and a stepped ground as a reflector are proposed to generate a broadband CP radiation. Besides, four L-shaped patches are introduced to effectively extend the bandwidth (BW) and extract a gain improvement together with the stepped ground. The measured -10 dB impedance BW is 132.08 % (1.36-6.65 GHz) and 3 dB axial ratio (AR) BW is 128.6% (1.39-6.4 GHz), closely with the simulated AR BW 136.73% (1.18-6.28 GHz), showing the proposed antenna features a wider bandwidth, comparing with other broadband CP antennas using similar structures. Due to the compact structure, the overall size of the proposed antenna is only 0.27λ l ×0.27λl©0.12λ l (where λ l is the free-space wavelength at 1.36 GHz). The proposed antenna has a wide application scope, such as the wireless network and satellite telecommunications.

Wideband Inhomogeneous-Polarizer Loaded Circularly Polarized SIW Horn Antenna for Broadband Millimeter-Wave Applications

An inhomogeneous-polarizer loaded substrate integrated waveguide (SIW) horn antenna is proposed to obtain wideband circularly polarized (CP) radiation. First, by introducing extended substrate and extra dielectric slabs around the horn radiating aperture, broadband impedance matching of the SIW horn can be realized. Then, a pure dielectric near-field CP polarizer is designed and placed in front of the horn to obtain broadband CP radiation. The polarizer is designed to feature inhomogeneous property for different polarization orientation illuminations. With this property, 90° phase difference for a pair of orthogonal linearly polarized waves can be realized. Two methods are utilized to analyze the inhomogeneous property of the polarizer and to provide detailed parameter estimation steps/formulas. The effects of polarizer size and oblique incidence are also studied, and a very wide 3 dB axial-ratio beamwidth of 104° is achieved. Measured results indicate that the proposed CP SIW horn can obtain a matching bandwidth greater than 40% (22–34 GHz) and a CP radiation bandwidth of 30% (22–29.8 GHz). Simple structure and wideband CP performance make it an attractive candidate for broadband millimeter-wave applications.

A Design of U-Shaped Slot Antenna With Broadband Dual Circularly Polarized Radiation

In this communication, a novel broadband dual circularly polarized (CP) antenna is presented. This antenna consists of an U-shaped slot to achieve broadband CP radiation and two 50- $\Omega $ microstrip-fed ports to realize both right-hand circular polarization and left-hand circular polarization at the same frequency band. The axial ratio bandwidth (ARBW) is greatly broadened by moving the feeding ports to upper portion of the U-shaped slot. To verify this design, the proposed antenna is fabricated and measured. The measured −10 dB reflection coefficient bandwidth is about 114.4% (1.80–6.61 GHz) and the 3-dB ARBW is approximately 110.5% (1.83–6.35 GHz). The isolation between two ports is better than 14.8 dB within the ARBW.

A Broadband Circularly Polarized Printed Monopole Antenna With Parasitic Strips

A novel printed monopole antenna is presented for circular polarization (CP) operation with broad axial-ratio (AR) bandwidth. The antenna is composed of a monopole, a ground plane, and two parasitic strips. By utilizing two spiral strips coupled by the monopole, broadband CP radiation is achieved. The measured results show the 10-dB impedance bandwidth is 2.75 GHz (1.75-4.5 GHz) and the antenna also has a 3-dB AR bandwidth of 64.7% (2.2 GHz, 2.3-4.5 GHz). The proposed antenna features simple structure and broad AR bandwidth, which is desirable for various wireless communication systems.

Broadband circularly polarized moon‐shaped monopole antenna

ABSTRACTA moon‐shaped printed monopole antenna with modified ground plane is proposed for broadband circularly polarized (CP) radiation. Proposed monopole antenna consists of a moon‐shaped radiator with a microstrip feed line. The moon‐shaped radiator and its ground‐plane shaped are optimized for broadband CP radiation. Impedance matching is improved using the quarter‐wave transformer along with microstrip line. The measured results of the prototype antenna on FR4 substrate are 1.67 GHz (2.08−3.75 GHz) for 2.5‐VSWR bandwidth, 1.48 GHz (2.28–3.76 GHz) for 3‐dB axial ratio (AR) bandwidth, and gain around 1.6 dBic across the 3‐dB AR bandwidth. Overall antenna volume is 0.466λ0 × 0.70λ0 × 0.008λ0 at 3.0 GHz. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1135–1139, 2015

Reactive impedance surface-based broadband circularly polarized Koch fractal boundary microstrip antenna

A circularly polarized (CP) broadband antenna is proposed for wireless applications in the range of 2–3 GHz frequency. It consists of asymmetrical Koch fractal boundary patch over a reactive impedance surface (RIS) substrate. The simulations of single-layer Koch fractal antenna, dual layer with square and fractal RIS elements are carried out in a systematic way for broadband CP radiation and corresponding results are presented. For better CP characteristics, properties of fractal curves and dimensions of RIS elements are optimized. The antenna with fractal RIS iteration order one (iteration1) is experimentally studied. The 10-dB return loss bandwidth is 50.35%, whereas 3-dB axial ratio bandwidth is 7.45%, which indicate that by applying fractals concept to RIS technique, with a single probe feed, broadband CP radiation can be obtained.

Dual-band operation of a circularly polarized radiator on a finite artificial magnetic conductor surface

This paper proposes a new way of designing a dual-band circularly polarized (CP) antenna by using a single-band CP radiator on a finite artificial magnetic conductor (AMC) surface. The AMC surface consists of a lattice of square metal plates on grounded dielectric substrate while the single-band radiator is a compact crossed dipole, which employs a 90° phase-delay line consisting of a vacant-quarter printed ring to generate broadband CP radiation. The dual-band operation is obtained by utilizing the original band generated by the radiator and the first additional band caused by surface waves propagating on the finite AMC surface. For verifying the design method, the proposed antenna is optimized for the L1 and L2 bands of the global positioning system with low-profile broadband characteristics and excellent CP radiation. The final design with an overall size of 85 × 85 × 11.493 mm3 (~0.3485λo × 0.3485λo × 0.0471λo at the 1.23 GHz) yields a measured impedance bandwidth of 1.202–1.706 GHz for the |S11| < –10 dB and 3-dB axial ratio bandwidths of 1.205–1.240 GHz and 1.530–1.625 GHz, respectively. Furthermore, the antenna yields right-hand circular polarization and high radiation efficiencies in both bands.

A Novel Bidirectional Antenna With Broadband Circularly Polarized Radiation in X-Band

A novel bidirectional antenna with a broadband circular polarization (CP) property in X-band is proposed. The CP characteristics are simply achieved by the asymmetrical Y-shaped feeding line. Both the impedance bandwidth and the axial-ratio (AR) bandwidth can be greatly improved by a through-via that is in series with an inductive strip and the polygon slot structure. The antenna is fabricated and measured for verifying the theory. A good agreement is achieved between the simulated and measured results. The 10-dB return-loss bandwidth is 31.4%, in which the AR is less than 2 dB. The measured radiation pattern shows a near-symmetry bidirectional radiation with the peak gain of 4.6 dBi. This antenna is a good candidate as a unit element in beamforming array applications.

BROADBAND CIRCULARLY POLARIZED DIELECTRIC RESONATOR ANTENNA WITH ANNULAR SLOT EXCITATION

A broadband circularly polarized (CP) cylindrical dielec- tric resonator antenna (DRA) is presented. The DRA is excited by an L-shaped microstrip feed line through the coupling of an annular slot in the ground plane. The broadband CP radiation is achieved by using two CP radiators, DRA and annular slot. Broadband impedance match is obtained by introducing an impedance transformer. The op- timal conflguration ofiers a 3-dB axial ratio bandwidth of 15.9%, from 6.22 to 7.28GHz, and a 10-dB impedance bandwidth of 21.3%, from 5.78 to 7.16GHz. The measured results for the constructed prototype are also exhibited and discussed.

Circularly polarized broadband high‐efficiency active integrated antenna

AbstractThis letter presents a circularly polarized (CP) broadband high‐efficiency active integrated antenna, where the broadband CP antenna is integrated directly with a broadband high‐efficiency class‐E power amplifier (PA). To achieve CP operation, a series feed using an L‐shaped microstrip feed line below the ground plane is used to provide a 90° phase shift between crossed slots. The antenna serves both functions of a broadband CP radiator and a broadband harmonics‐termination load network for the class‐E PA. Measures results demonstrate both broadband CP radiation and high efficiency. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2145–2148, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21940

Compact broadband circularly polarized square microstrip antenna

A new design for achieving compact broadband circular polarization (CP) radiation of a square microstrip antenna is presented. The compactness of the microstrip antenna is easily obtained by inserting four slits of equal lengths at the patch edges, and broadband CP radiation is achieved simply by loading a chip resistor at a proper position in the patch. The present proposed CP design has been implemented with an increase of about 50% in CP bandwidth as compared to the compact CP design using inserted slits of unequal lengths. Details of the antenna design and experimental results are presented and discussed. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 21: 423–425, 1999.

Compact broadband circularly polarized square microstrip antenna

A new design for achieving compact broadband circular polarization (CP) radiation of a square microstrip antenna is presented. The compactness of the microstrip antenna is easily obtained by inserting four slits of equal lengths at the patch edges, and broadband CP radiation is achieved simply by loading a chip resistor at a proper position in the patch. The present proposed CP design has been implemented with an increase of about 50% in CP bandwidth as compared to the compact CP design using inserted slits of unequal lengths. Details of the antenna design and experimental results are presented and discussed. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 21: 423–425, 1999.