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Wide Axial Ratio Bandwidth, High Gain, and Low Profile Cavity Backed Circularly Polarized Elliptical Array for Satellite Applications

Wide Axial Ratio Bandwidth, High Gain, and Low Profile Cavity Backed Circularly Polarized Elliptical Array for Satellite Applications

Abstract—In this paper, a novel wide axial ratio bandwidth (ARBW), high gain, and low profile left- hand circularly polarized [4 × 4] elliptical microstrip array suitable for Ku-band satellite TV reception applications is introduced. A careful study has been done to get the optimum design to be suited for these application requirements. A circularly polarized microstrip patch with two stubs opposite to each other to produce two orthogonal modes is presented. The proposed element has 1.49 GHz 10-dB return loss bandwidth (RLBW), 0.44 GHz 3-dB Axial-ratio band (ARBW), and 6.9 dBi gain. A novel substrate integrated waveguide (SIW) feeding structure is investigated. Using the advantage of the output ports phase response of the SIW feeding network, two structures have been investigated. First, a [2 × 2] circular array has been designed, and although it has reached a good RLBW, this structure does not achieve the required ARBW for the above-mentioned application. Further, a compact [2 × 2] sequential feeding network is designed to widen the ARBW. The measurement shows a very good result with about 12 dBi gain, 14.8% RLBW, and 12% ARBW. Finally, a [4 × 4] duple sequential feeding array is designed to increase the gain of the antenna to about 19 dBi, with 13% RLBW and 20.7% ARBW. In addition to that, the final antenna profile is 0 . 0184 λ .
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Wideband Circularly Polaried Cross Bowtie Dipole Antenna with Axial-Ratio Bandwidth Enhancement

Wideband Circularly Polaried Cross Bowtie Dipole Antenna with Axial-Ratio Bandwidth Enhancement

Abstract—A wideband circularly polarized (CP) cross-dipole antenna is proposed for wireless applications. In this design, four parasitic square patches are utilized around the radiation patch to enhance the Axial-ratio (AR) bandwidth. By employing the bowtie-shape dipoles, the proposed antenna can achieve a wide impedance bandwidth. Meanwhile, by integrating with a curved-delay line which provides a 90 ◦ phase difference, the proposed antenna can radiate a CP pattern. A prototype is calculated, fabricated, and measured. Good agreement between the simulated and measured results is achieved. The measured results show an impedance bandwidth for VSWR ≤ 2 of 47.73% (1.93– 3.14 GHz) and a 3-dB AR bandwidth of 42.8% (2.00–3.09 GHz).
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Design and Analysis of Microstrip Patch Antenna for WLAN and Vehicular Communication

Design and Analysis of Microstrip Patch Antenna for WLAN and Vehicular Communication

As depicted in Fig. 9(a), varying the total length of L-shaped slot changes resonant frequency and impedance bandwidth of monopole antenna. It is observed that lowering the length of slot shifts resonant frequency to higher side with impedance bandwidth of 15.77%, while higher value of slot shifts resonant frequency to lower side with impedance bandwidth of 23%. This is because length of L-shaped slot modifies the length of current in the ground plane. Though the impedance bandwidth has been increased, this change in length shows vital impact on axial ratio bandwidth. From Fig. 9(b), it is observed that the change on slot length affects axial ratio and axial ratio bandwidth. For higher value of slot length, axial ratio shifts to lower side and resonates at 2.29 GHz having axial ratio bandwidth from 2.22 to 2.36 GHz, which is not desired lower WLAN band. For lower value of slot length, axial ratio becomes > 3 dB. Therefore, the total length of L-shaped slot has been optimized at L = 13 mm. To realized dual-band CP antenna, a square patch with diagonally opposite corners cut is placed offset beneath with respect to monopole. This patch resonates at 5.9 GHz vehicular band having 15.73% and 14.16% of impedance and axial ratio bandwidth, respectively. The return loss and axial ratio characteristics are shown in Fig. 10.
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A Single-Layer and Compact Circularly Polarized Wideband Slot Antenna Based on ``Bent Feed''

A Single-Layer and Compact Circularly Polarized Wideband Slot Antenna Based on ``Bent Feed''

With the rapid development of wireless communication systems, broadband circularly polarized (CP) antennas are highly demanded. Recently, the design of a broadband CP antenna has been a topic of concern for antenna designers. However, the traditional CP antennas suffer from narrow impedance and axial ratio bandwidth.

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Design of Circularly Polarized Planar Magneto-Electric Dipole Antenna

Design of Circularly Polarized Planar Magneto-Electric Dipole Antenna

A novel and simple circularly polarized planar magneto-electric dipole antenna with inverted U-shaped feed design has been designed and fabricated. The measured and simulated results indicate that it possesses 21.1% impedance bandwidth, from 8.9 GHz–11.0 GHz and provides 3-dB axial ratio bandwidth of 9.52% covering 10 GHz–11.0 GHz. The antenna exhibits stable omnidirectional radiation pattern with almost equal E -plane and H -plane radiation patterns and provides a peak gain of 6.2 dBi. Due to its good electrical characteristics, the antenna is suitable for satellite and RADAR communication in X- band.
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Circularly Polarized Array Antenna Using the Sequential Rotation Network Feeding for X-Band Communication

Circularly Polarized Array Antenna Using the Sequential Rotation Network Feeding for X-Band Communication

Figure 11(b) depicts a comparison of simulated and measured circularly polarized characteristics. It shows that its simulated result has a wider axial ratio bandwidth than the measured result, obtaining 12.2% with the lower frequency (8.0 GHz) at 7.3 GHz and higher frequency (8.4 GHz) at 8.44 GHz. This simulated result has the deepest point of curve at 7.86 GHz obtaining 0.13 dB, then in the center frequency of 8.2 GHz obtaining 2.09 dB. On the other hand, measured result produces a narrower bandwidth of axial ratio about 11%, with the lower frequency at 7.58 GHz and the higher frequency at 8.5 GHz. This measurement result has the deepest frequency at 8.22 GHz obtaining 0.25 dB, and then in the centre frequency (8.2 GHz) obtaining 0.25 dB. Compared to the simulated one, the measured result is much narrower, but its result has deeper axial ratio and much deeper also at the center frequency, which means that the measurement one is more circularly polarized. In this case, the discrepancies of the results are caused by imprecision in fabrication or some shifting in the fusion between the first and second substrates.
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An Improvement to Directional Equiangular Spiral Antenna with Wide CP Band, High Gain and Low Profile

An Improvement to Directional Equiangular Spiral Antenna with Wide CP Band, High Gain and Low Profile

The simulated axial ratios of Ant1 and Ant2 versus frequency are shown in Fig. 9. The simulated axial ratio of Ant1 is less than 3 dB in the band almost from 4.2 GHz to 8.9 GHz (71.2%) except in 7.2 GHz. And the simulated axial ratio of Ant2 is less than 3 dB in the band almost from 4.4 GHz to 9.5 GHz (73.4%) except the same frequency 7.2 GHz. The comparison shows that the two parasitic layers are able to broaden the spiral antenna axial ratio bandwidth in a certain extent due to the self- rotational structure of parasitic layers, and the induced surface current on the parasitic layers is almost rotated in distribution.
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Wideband Cavity-Backed Crossed Dipoles for Circular Polarization

Wideband Cavity-Backed Crossed Dipoles for Circular Polarization

A novel CBCDA is investigated in the paper. By using the crossed dipoles as an exciter, broadband CP performances are achieved. From the simulated results, the antenna shows a 3-dB axial-ratio bandwidth of 50%, a broadside gain of 7–10 dBi and symmetrical radiation patterns. Parametric studies are performed for further understanding the operating principles and reference to practical designs.

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Wideband Single-Feed Circularly Polarized Antenna

Wideband Single-Feed Circularly Polarized Antenna

Circularly polarized antennas are of great importance in modern wireless communication, radar, RFID and sensor systems, due to their stability of signal reception and smashing mobility. Recently, patch antennas have attracted increasing attention as an approach for realizing the circular polarization [1–7]. By using four sequential-rotation proximity-coupled L-probes, the antenna in [1] delivers a measured 3- dB axial ratio bandwidth of 82% from 1 to 2.4 GHz. Four sequentially-rotated-fed linearly polarized disks located in a cavity-backed circular slot are used in [2], and the 3-dB axial ratio bandwidth of this antenna is 54.5%. But the feeding network in [1, 2] needs large space and increase complexity of the antenna design. Therefore, the single-feed circularly polarized patch antenna has received much attention for its simple structure. In [3], the circularly polarized antenna has a lower notched circular patch with a capacitive feeding and an upper parasitic notched patch, and its 3-dB axial ratio bandwidth is 10%. By using the horizontally meandered strip (HMS) feed technique, the circular polarization bandwidth can be enhanced to 13.5% [4]. An H-shaped patch antenna is presented in [5]. This antenna features a much wider axial ratio bandwidth of 19.4%. In [6], a novel cross-dipole and curved-delay feeding line are proposed. The antenna has a 3-dB axial ratio bandwidth of 27%. It can be seen that the axial ratio bandwidth of the single-feed circularly polarized antenna is usually very narrow, though its structure is simple.
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Circularly-Polarized Stacked Annular-Ring Microstrip Antenna

Circularly-Polarized Stacked Annular-Ring Microstrip Antenna

The aim of this paper is to use aperture feeding as an alternative technique to improve the performance (impedance and axial ratio bandwidth) of multi-band ring microstrip antennas. In particular, a dual-band circularly-polarized antenna based on stacked annular-ring microstrip patches fed by four bow-tie apertures is designed, fabricated and measured. A broadband feeding network has been used to obtain the required phase shift thus allowing to improve the axial ratio in the direction of maximum radiation. This feeding network is based on the broadband phase shifter presented in [16]. We will also show that the size and shape of the substrate that supports the radiating elements of the antenna, i.e., the annular-rings, plays an important part in the quality of the axial ratio for low elevation angles.
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Design of a Circularly Polarized Microstrip Antenna for WLAN

Design of a Circularly Polarized Microstrip Antenna for WLAN

Abstract—The design and performance of a circularly polarized microstrip patch antenna, for the application in Wireless Local Area Network (WLAN), are reported here. The antenna is a proximity coupled microstrip patch antenna where the radiating patch is loaded by a V-slot. This miniaturized microstrip antenna has wide bandwidth in the frequency band of WLAN and exhibits circularly polarized far field with very good axial ratio bandwidth. The simulated results using IE3D software are verified by measurement.

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A New Spiral Antenna with Improved Axial Ratio and Shorted Arm Length

A New Spiral Antenna with Improved Axial Ratio and Shorted Arm Length

In many occasions, short arm length is necessary. In recent studies, spiral antennas with planar feeding structure have attracted more attraction. The traditional balun usually has a significantly long length and extends to the third dimension. Feeding the equiangular spiral with a transmission line that follows the metal layer beneath the spiral to the center point is proposed [8]. The vertical balun is replaced by parallel-plane feeding structure, and the overall size of the antenna is largely reduced. But it is impossible to feed Archimedean spiral antenna the same way because of the long and thin arm. However, Archimedean spiral antenna has a noticeable advantage at axial ratio bandwidth over its equiangular counterpart. Under this condition, improving radiation characteristics as well as reducing the arm length is necessary.
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A Comparative Analysis of a Circularly Polarized Microstrip Patch Antenna with & Without U Slot

A Comparative Analysis of a Circularly Polarized Microstrip Patch Antenna with & Without U Slot

patch antenna at L-band is designed. The antenna contains a U-Slot and designed with DGS technique to reduce the size of antenna. U-slot etched in the antenna allowed the fabrication on a high-dielectric-constant (10.2) substrate that achieves a reasonable axial-ratio bandwidth. Circular Polarization can be generated on a rectangular patch antenna by truncating two opposite corners of patch. In this paper a comparison has been done between a CP Microstrip antenna with and without U-Slot. At the operating frequency of 1.575 GHz with the size of the patch is 25mm X 25mm, while ground plane of 50mm X 50mm and the thickness of the substrate is 10.2 mm.. The parameters of antenna like return loss, axial ratio, RHCP and LHCP, gain are analyzed using CST MSW Software. The operating frequency is 1.521 GHz.
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Design of a Broadband Circularly Polarized Antenna Array

Design of a Broadband Circularly Polarized Antenna Array

In this paper, a sequentially rotated feed circular polarized antenna array with broadband performances is proposed. According to the experimental results, the − 10 dB impedance bandwidth is 72.9% (4.62–9.92 GHz), and a 3 dB axial ratio bandwidth is 62.2% (4.48–8.52 GHz). The paper is arranged as follows. In Section 2, a broadband circularly polarized antenna element is designed in detail. In Section 3, the element is used to form a four-element antenna array. The array is fabricated and measured in Section 4. Finally, conclusion is made in Section 5.

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Design of Broadband Circular Polarization Truncated Horn Antenna with Single Feed

Design of Broadband Circular Polarization Truncated Horn Antenna with Single Feed

In this paper, we present the design of a broadband CP truncated horn antenna with single feed. It does not require any complex feeding structure and uses only a coaxial feed extended with a simple electric field coupling probe. The corners of the horn are truncated to generate CP modes, and a broad axial ratio bandwidth which is insensitive to the probe feed dimension is achieved. Simulated and measured results of an S band truncated horn antenna are presented. The designed antenna has a measured 3 dB axial ratio of 26% with aperture efficiency of 60%. All simulations are carried out using HFSS [10].
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A Terahertz Quarter Wave Plate Based on Staggered Split Ring Resonators

A Terahertz Quarter Wave Plate Based on Staggered Split Ring Resonators

Abstract—In this paper, we propose a transmissive quarter wave plate (QWP) which can provide linear-to-circular polarization conversion in terahertz (THz). The structure is composed of one dielectric layer with staggered split ring resonators (SSRRs) on both sides. The simulation results show that the proposed structure can offer a nearly pure left circularly polarized wave with 3 dB axial ratio bandwidth of 0.337 THz; meanwhile, the bandwidth of polarization conversion efficiency beyond 80% reaches 0.170 THz. Additionally, the distributions of surface currents and electric field are discussed to explain the physical mechanism of the proposed structure. The linear-to-circular polarization conversion can be attributed to the inductance effect and capacitance effect between SSRRs. Finally, we validate the performance of the proposed THz-QWP. Such a device could potentially be used in THz communications, THz imaging, and THz sensing.
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Broadband dipole antenna for DOA systems applications

Broadband dipole antenna for DOA systems applications

The design of Microstrip antennas with circular polarization and wide bandwidth axial ratio is complex in most cases, in this sense, a circular patch design with circular polarization and reconfigurable sense of rotation is presented in [6] achieving 27.39% impedance bandwidth for a reflection coefficient magnitude 𝑆11 < −10𝑑𝐵 in the range from 2.295 𝐺𝐻𝑧 to 3.025 𝐺𝐻𝑧 , a maximum gain of 6.04 𝑑𝐵𝑖 and a 13% axial ratio bandwidth for -3dB reference. Moreover, a design with circular ring geometry short-circuited and reconfigurable sense of rotation is presented in [7] where a 33.33% impedance bandwidth in 1.9𝐺𝐻𝑧 - 2.66𝐺𝐻𝑧 frequency range for a reflection coefficient less than -10 dB was achieved, a
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A Novel CPW-Fed Planar Monopole Antenna with Broadband Circularly Polarization

A Novel CPW-Fed Planar Monopole Antenna with Broadband Circularly Polarization

For deploying a transmitter and a receiver without causing a polarization mismatch between them, circular polarization is becoming popular in wireless communications to improve system performance, providing better mobility and weather penetration compared to linearly polarized (LP) antennas [1]. Many designs of circularly polarized (CP) patch antennas with single or dual feed structures are proposed by exciting two orthogonal modes with 90 ◦ phase difference [2]. Meanwhile, CP antennas with broad bandwidth are needed in modern communication applications to obtain a high data rate and provide high-speed multimedia service [3]. In order to obtain a wide impedance bandwidth and wide axial ratio bandwidth, a variety of printed monopole antenna configurations have been proposed in research papers [4–7], designing an L-shaped monopole slot antenna with a C-shaped feed to realized CP operation [4], placing a power division network between a slot and a monopole for generating circular polarization [5], utilizing two parasitic strips to achieve a broadband CP radiation [6], or protruding a G-shaped parasitic strip into a C-shaped monopole antenna to facilitate wide ARBW [7]. Being fed by CPW-fed structures [8–14], a microstrip antenna can obtain wide operating bandwidth too, and its single metallic layer is better to meet the requirements of low profile and is easier to integrate with the active and monolithic circuits than traditional antennas. By etching modified slots in the ground plane [8–11], designing two orthogonal equal-size patches [12], or adding parasitic strips [13, 14], broadband CPW-fed CP antennas are achieved.
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A Non Dimensional Consideration in Combustor Axial Stress Computations

A Non Dimensional Consideration in Combustor Axial Stress Computations

Kubo et al. [4] investigated a multidisciplinary prob- lem of heat conduction, elastic deformation, heat transfer, liquid flow. They used inverse method for determining the optimum thermal load history which reduced tran- sient thermal stress. Temperature history functions were introduced to ensure the continuity of the temperature increasing rate. The multidisciplinary complex problem was decomposed into heat transfer and thermal stress problems. Ootoa et al. [5] determined the temperature and thermal stress distribution in the cross-section of a non-homogenous hollow circular cylinder due to a mov- ing heat source in the axial direction, and found that; the maximum temperature occurs at the region through which the moving heat source passed. All of the above used non-dimensional functions of stress and found that
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The Axial Ratio of Planar Arrays with Random Element Errors

The Axial Ratio of Planar Arrays with Random Element Errors

In Section 2 we present the crossed dipoles array model for the planar array, and we define the errors in the feeding currents. In Section 3 we derive the approximate expression of the Axial Ratio (AR) as a result of the errors. In Section 4 we validate the resulting equation against the original model and observe the effect of the errors with random trial simulations.

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