Circularly Polarized Slot Antenna Research Articles

Design of Dual Band Dual Sense Circularly Polarized Wide Slot Antenna with C-shaped Radiator for Wireless Applications

Abstract A low profile wide slot antenna for dual band and dual sense circular polarization (CP) is proposed here and is simulated by using HFSS simulation software.The proposed antenna having a C shaped patch for dual band operation and a wide square slot etched on the ground with two strips for CP operation. In between radiating patch and ground plane, designed antenna has a layer of easily available dielectric (FR-4) material. Proposed antenna shows an impedance bandwidth of 13.8 % at 2.38 GHz of centre frequency and 9.7 % at 4.43 GHz of centre frequency for lower and upper band respectively. The 3-dB axial ratio (AR) bandwidths for lower and upper band are 18.8 % (at 2.44 GHz of centre frequency) and 13.3 % (at 4.29 GHz of centre frequency), respectively. The peak gain for the lower and upper band is found as 4.1 dBi and 3.3 dBi, respectively. A close agreement has been found between the simulated and the measured results.

Broadband Circularly Polarized Slot Antenna Loaded by a Multiple-Circular-Sector Patch.

In this paper, a microstrip-fed broadband circularly polarized (CP) slot antenna is presented. CP operation can be attained simply by embedding an S-shaped strip. By loading with a multiple-circular-sector patch, which consists of 12 circular-sector patches with identical central angles of 30° and different radii, the 3 dB axial ratio (AR) bandwidth is significantly broadened. To validate the performance of the proposed antenna, an antenna prototype is fabricated and tested. The fabricated antenna is 54 mm × 54 mm × 0.8 mm in size. The measured −10 dB reflection and 3 dB AR bandwidths are 81.06% (1.68–3.97 GHz) and 70.55% (1.89–3.95 GHz), respectively. Within the 3 dB AR bandwidth, the measured peak gain is 3.81 dBic. Reasonable agreement is also obtained between the measured and simulated results.

RCS reduction and gain enhancement of SRR inspired circularly polarized slot antenna using metasurface

In this work, a novel Circularly Polarized (CP) slot antenna is proposed for low RCS and high gain applications. The proposed antenna is designed in two phases. Initially, a metasurface is designed, which is composed of two similar artificial magnetic conductor (AMC) unit cells arranged orthogonally in chessboard-like configuration for broadband RCS reduction. Then, the CP slot antenna is designed by placing dual SRR on the backside of the slot for impedance matching and to achieve circular polarization. Detailed analysis is conducted to investigate the performance of metasurface loaded CP slot antenna. The proposed antenna shows 10 dB RCS reduction over the bandwidth of 41.3% at boresight direction compared to CP slot antenna. The maximum in-band and out-of-band RCS reduction achieved is 24 dB and 20 dB, respectively. The maximum gain of the antenna is also increased by 2.7 dB as a result of parasitic radiation of the metasurface and an improvement in overall performance of the antenna is observed by the employment of metasurface. Measured results of the fabricated prototype are in good agreement with the simulated results.

Three‐layered balanced circularly polarized slot antenna with high common‐mode suppression

AbstractThis article proposes the design of a three‐layered balanced circularly polarized (CP) antenna using two tightly stacked conventional single‐ended CP slot antennas. With a 180° delay line inserted into one of the two feeding microstrip lines that form the balanced feedline, differential‐mode (DM) input signals can excite CP radiation in the broadside directions with a measured (simulated) axial ratio of as low as 1.3 (0.86) dB. Common‐mode (CM) input signals can be well rejected with a measured (simulated) CM return loss of <0.4 (0.5) dB in the DM impedance band. In addition, only a very small proportion of the CM (DM) input signal is converted into a DM (CM) reflected one. These nice properties of the possibly first reported balanced CP antenna were all achieved without placing before the radiation element a CM‐suppression filter.

Dual-Patch Polarization Conversion Metasurface-Based Wideband Circular Polarization Slot Antenna

In this paper, a novel polarization conversion (PC) structure is introduced, and its use with a wideband, wide 3-dB axial-ratio (AR) beam, low-radar-cross-section (RCS) circular polarization (CP) slot antenna is suggested. The unit cell of the proposed PC metasurface (PCM) consists of square and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L$ </tex-math></inline-formula> -shaped patches separated by an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L$ </tex-math></inline-formula> -shaped slot printed on an FR4 substrate. The mechanisms for linear to circular polarization and bandwidth improvement of a conventional antenna are analyzed theoretically. Through numerical optimizations and parametric studies, a simulated 10-dB impedance bandwidth of 42.7% (4.15–6.4 GHz) and a 3-dB AR bandwidth of 26.2% (4.8–6.25 GHz) are achieved by the proposed antenna. As the simulation demonstrates, the proposed antenna achieves an average 20-dB RCS reduction in a wide band from 5.25 to 6.8 GHz compared with a conventional slot antenna covered by the PC band. In addition, compared with the previously reported work, the PCM-based CP antenna exhibits a larger 3-dB AR beam width of 200° in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xoz</i> plane and 120° in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">yoz</i> plane, and a wider CP bandwidth within the operational bandwidth. Finally, an overall volume of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.55\lambda _{0}\times 0.55\lambda _{0}\times 0.05\lambda _{0}$ </tex-math></inline-formula> centered at 5.275 GHz is fabricated and measured, demonstrating good agreement with the simulation results.

A broadband CPW-fed dual circularly polarized slot antenna with modified L-shaped monopoles

A broadband CPW-fed dual circularly polarized slot antenna with modified L-shaped monopoles

Broadband Circularly Polarized Slot Antenna Array Fed by Asymmetric CPW for C-Band Applications

ABSTRACTIn this manuscript, a new design of broadband circularly polarized (CP) array antenna is presented. A 2 × 2 planar array antenna is accomplished using the proposed CP diamond-shaped slot element with an L-shaped patch. The feed network employs a 180-degree rat-race hybrid coupler to realize a −3 dB power split, equal in magnitude, 180-degree difference in phase. Two branch-line couplers then divide the signal energy into two paths and give the signal to each of the output branches with the same amplitude, but phase-shifted by 90 degrees, wherein the relative phases at four feed points are 0, 90, 180, and 270 degrees. The final dimensions of the 2 × 2 element array are 112 × 97 × 0.8 mm3. The simulated result shows that the impedance bandwidth for a voltage standing wave ratio (VSWR) < 2 is around 39.86% (4.78–7.16 GHz), and the 3-dB simulated AR (axial ratio) bandwidth is about 24.2% (4.83–6.16 GHz), and the antenna has a peak gain of 7.69 dBi over the bandwidth.

Low-Profile Millimeter-Wave SIW Cavity-Backed Dual-Band Circularly Polarized Antenna

A single-fed low-profile millimeter-wave substrate-integrated waveguide (SIW) cavity-backed slot antenna for dual-band circular polarization (CP) applications is proposed. First, by employing two annular exponential slots carved on the surface of a circular SIW cavity, dual-band CP radiation is achieved. Two different modes, that is, the cavity mode and the surface mode, separately modulated by the cavity field distribution and the surface current, are investigated. They are utilized to achieve the dual-band CP radiation. Next, a two-order matching circuit using inductor windows is introduced to achieve dual-band matching at the low-profile antenna design with the help of the differential evolution method. Finally, for the dual-band CP application at 37.5 and 47.8 GHz, an antenna prototype is fabricated and its performance is evaluated. Simulation and measurement results agree very well.

CPW-Fed Circularly Polarized Slot Antenna

This article demonstrates the coplanar waveguide (CPW) feed L- slot microstrip antenna for multi frequency band operation is presented. The proposed antenna is excited by a single CPW feed connected to a Microstrip antenna. In this radiating patch and feed are etched on the same dielectric material. A SMA connector is used to connect the feed strip which couples the energy to a radiating patch by capacitive feed. The length and width are designed to obtained dual band frequency range. A truncation is used for multiband operations and for proper impedance matching. L- slot is used to increase the depth of S11 parameter.

Circularly‐polarised slot array with high front‐to‐back ratio and low axial ratio

A novel design for circularly-polarised (CP) arrays is proposed. The proposed array is composed of dual CP slot antenna elements arranged in a face-to-face configuration, and they are simultaneously excited through a slot line. By properly controlling the excitation amplitudes and phases of the two radiating elements, the cross polarisation and back radiation of the array can be effectively reduced. From the measured results, the proposed array can give an axial ratio of lower than 1 dB and a front-to-back ratio of higher than 12 dB within a 10 dB-return-loss bandwidth of >16%. Simulation results obtained with high frequency structure simulator (HFSS) also agree well with the experimental data.

CPW-fed Circularly Polarized Slot Antenna with Small Gap and Stick-shaped Shorted Strip for UHF FRID Readers

Abstract A new circularly polarized (CP) slot antenna with a small gap and a stick-shaped shorted strip is presented. The proposed antenna has a sufficient bandwidth for ultrahigh frequency (UHF) radio-frequency identification (RFID) reader applications. The antenna structure consists of a rectangular slot with a small gap, a stick-shaped shorted strip and a 50 Ω coplanar waveguide (CPW) feedline with an asymmetrical ground plane. By using the stick -shaped shorted strip to disturb magnetic current distribution on the slot, the CP radiation can be generated. The measured results demonstrate that the proposed antenna can reach a 10 dB return loss impedance bandwidth of 14.1 % (894–1030 MHz) and a 3 dB axial ratio (AR) bandwidth of 6.4 % (910–970 MHz). The whole antenna size is 80 × 80 × 1.6 mm3.

Dual-band capacitively loaded annular-ring slot antenna for dual-sense circular polarization

This paper investigates a simplified and new capacitively loaded annular-ring slot antenna (ARSA) for dual-band and dual-sense circular polarization. The antenna is comprised of two concentric annular-ring slots coupled to a microstrip feed line to achieve dual-band operation. With introducing proper distributed capacitances fulfilled by two closely spaced T-shaped arc strips across the outer and inner annular-ring slots at opposite positions with respect to the microstrip feed line, the dual-sense circular polarization can hence be obtained. The antenna features that the impedance and circular polarization characteristic for the upper band can be independently adjusted. Numerical analysis and experimental validation have been carried out. The measured 10-dB return loss impedance bandwidths for both bands are greater than 22.0%. The measured 3-dB axial ratio (AR) bandwidths are 3.6 and 5.6%, respectively, for the lower and upper bands.

Wideband CP slot antenna with backed FSS reflector

A wideband, circularly polarised (CP), frequency selective surfaces (FSSs) backed dual-slot antenna is designed and fabricated. It consists of two crescent-shaped slots, an L-shaped feed-line and an FSS reflector. The single crescent-shaped slot structure is employed to obtain CP radiation first. Then, it is found that the beam-tilted problem can be solved by extended dual-slot design. With the FSS reflector placed under the dual-slot antenna, unidirectional radiation is achieved and axial ratio bandwidth of the proposed antenna could be improved simultaneously. The measured results offer a 56% (3.5 GHz, 4.5–8.0 GHz) CP bandwidth, and the 10 dB impedance bandwidth is 84.8% (5.48 GHz, 3.72–9.20 GHz). By introducing the FSS reflector, 10 dBi of peak gain is also obtained at 5.6 GHz which is greatly enhanced when compared with the antenna without FSS. The advantages of the proposed antenna are the simple structure, high gain and broad CP bandwidth.

A New Compact and High Gain Circularly-Polarized Slot Antenna Array for Ku-Band Mobile Satellite TV Reception

A compact and high-gain SIW-fed circularly polarized (CP) slot-antenna array with a stacked feed structure is presented for the application of Ku-band high-data-rate satellite communications. First, a novel probe-fed SIW cavity with four slots etched on the top surface is proposed as a high-gain radiating element for the array. The four slots in the cavity act as a $2\times2$ array, and its directivity is 2.15 and 1.43 dB greater than that of the cavity-backed antenna of the same size using ring slot and split ring slot, respectively. Second, a compact 1–4 SIW power divider is designed for exciting a subarray. Third, the $2\times2$ subarray is further expanded to an $8\times16$ array by adopting an additional layer of 1–32 SIW feeding network to meet the gain requirement of the Ku-band mobile satellite TV reception. Finally, experiments are carried out to verify the designed prototypes. Measured results show that proposed 128-element array has a relative impedance bandwidth of 4.8% (11.84 to 12.42 GHz), AR bandwidth of 130 MHz (12.01 to 12.14 GHz), and a peak gain of 26.8 dBic at 12.06 GHz. Owing to the simple feeding networks and the compact radiating element, the antenna has a compact size of $6.04\lambda _{ {0}} \times 11.96\lambda _{ {0}} \times 0.1\lambda _{ {0}}$ . Experimental results show that the proposed CP antenna array is suitable for applications of Ku-band mobile satellite TV reception.

Polarization conversion of metasurface for the application of wide band low-profile circular polarization slot antenna

In this letter, based on a corner-cut square metasurface, a planar polarization conversion structure is presented and the application for wide band low-profile circular polarization (CP) slot antenna is proposed. The mechanisms for achieving the CP state from a linearly polarized incident wave and for broadening the working bandwidth of conventional slot antenna are analyzed theoretically. The wide band low-profile CP slot antenna is achieved with numerical optimizations and parameter studies. Both simulations and measurements are performed to demonstrate the proposed antenna, and good agreements are obtained. Such results will open the path for polarization conversion metasurfaces used in the CP antenna area.

Circular slot antenna with capacitive loading technique for broad circularly polarized bandwidth

ABSTRACTA microstrip‐fed circular slot antenna design is proposed. To excite good CP (circularly polarized) radiation, the technique of loading a cross patch (with unequal arm lengths) into the circular slot is initially applied. Here, good impedance matching can be further attained by dividing the cross patch into two equal sections with a gap loaded in between them, in which this gap will induce a capacitive loading effects on the proposed antenna. The measured results shown that the proposed antenna has 10 dB impedance bandwidth of 36.4% (2116–3124 MHz), and its corresponding CP bandwidth (along 3 dB axial ratio, AR) was 12.3% (2345–2655 MHz). In addition to that, the proposed CP slot antenna has also yielded peak gains of more than 3.3 dBic across the CP bandwidth. Detailed process of designing the proposed CP slot antenna is explicitly shown, and vital parametric studies were also conducted by simulation. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:715–720, 2016

Design Method for Wideband Circularly Polarized Slot Antennas

A compact ultrawideband (UWB) circularly polarized (CP) slot antenna is proposed with a methodology for automated reoptimization for packaging with proprietary devices. The slot structure employs a dual-feed with an integrated compact UWB phase shifter. The design process involves an advanced optimization algorithm and demonstrates the use of spline curves for generation of CP signals. These allow easy optimization, while preserving phase coherency across a wideband. The prototyped antenna has a CP bandwidth of 54% (from 3.2 to 6.1 GHz).

Wideband Compact CPW-Fed Circularly Polarized Antenna for Universal UHF RFID Reader

A compact circularly polarized slot antenna is proposed in this communication, which has a much wider operation bandwidth compared to the antennas with similar sizes. This antenna is designed for universal ultrahigh frequency (UHF) radio-frequency identification (RFID) reader applications. The antenna is coplanar waveguide (CPW) fed by an L-shaped feeding line. To achieve good impedance matching and broadband CP operation, two L-shaped strip lines are inserted into the circular slot in the ground plane. The measured 10-dB return loss bandwidth is 380 MHz (618-998 MHz, 47.0% centered at 808 MHz). The measured 3-dB axial ratio bandwidth is about 332 MHz (791-1123 MHz, 34.7% centered at 957 MHz). The overall size of the antenna is 120 × 120 × 0.8 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> .

Reconfigurable wide band circularly polarized antenna array for WiMAX, C-Band,a and ITU-R applications with enhanced sequentially rotated feed network

In this article, a wide-band circularly polarized slot antenna array with reconfigurable feed-network for WiMAX, C-Band, and ITU-R applications is proposed. Different novel methods are used in proposed array to improve antenna features such as impedance matching, 3 dB axial-ratio bandwidth (ARBW), gain, and destructive coupling effects. Miniaturized dual-feed square slot antenna, with one attached L-shaped strip and a pair of T-shaped strip at ground surface for improving impedance matching and circular polarization (CP) purity, is presented. For further enhancement of CP attributes, reconfigurable sequentially rotated feed network is utilized to obtain wider 3 dB ARBW. Furthermore reconfigurable property of network gives controlling Right and Left handed CPs, respectively. Finally, a special form of Electromagnetic Band gap structure is employed on top layer of substrate that provides high isolation between radiating elements and array feed network to enhance overall performance of antenna. The measured results depict 3 dB ARBW from 4.6 to 7.2 GHz, impedance bandwidth from 3.3 to 8.8 GHz for VWSR<2, and peak gain of 10 dBi at 6 GHz. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:825–833, 2015.

Dual frequency and dual circular polarization slot antenna for BeiDou navigation satellite system applications

ABSTRACTA new design of a dual frequency and dual circular polarization slot ring antenna for BeiDou Navigation Satellite System (BDS) applications is presented in this article. The dual frequency is achieved by two slot rings and the dual circular polarization is obtained by asymmetry slots adjacent to the rings. An antenna used for BDS applications with optimized parameters is designed, fabricated, and measured. Measured results show that the proposed antenna has good circular polarization for both right‐hand circular polarization and left‐hand circular polarization. The −10 dB return loss relative bandwidths for the lower and higher bands are about 4.4 and 12.0 %, respectively. The 3 dB axial ratio bandwidths are both about 5% with respect to the center frequencies of 1615.68 and 2491.75 MHz, respectively. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2222–2225, 2014