Good Axial Ratio Research Articles

Broadband circularly polarized spiral antenna array using sequentially rotated technique

A circularly polarized (CP) spiral antenna array for wideband application is presented, which employs a simple single-arm spiral antenna (SASA), as the radiating element. By introducing a small round disc backed near the antenna center and loading a termination resistor, the SASA achieves a wide im pedance bandwidth without a balun circuit and a good axial ratio (AR) performance, respectively. A total of four array elements are used in the 2 × 2 configuration to obtain a higher gain. Particularly, a method of sequentially rotating the elements is used to improve the axial ratio. The array performs an impedance bandwidth for VSWR ≤ 1.5 of 40% ranging from 1.25 to 1.88 GHz, an excellent AR of better than 0.74 dB, and a gain variation from 11.34 to 14.56 dB within the operating band. Measured and simulated results presented for the array confirm its wide impedance, axial ratio, and gain bandwidths. Acceptable agreement between the simulation and measured results validates the proposed design.

위성수신용 마이크로스트립 어레이 안테나 설계

본 논문은 현재 직접 위성수신용 안테나로 사용 중인 파라볼릭 안테나를 대체할 수 있는 마이크로스트립 어레이 안테나를 연구하였다. 마이크로스트립 어레이 안테나는 극히 제한적인 분야에서 사용되었으나 직접위성 수신용 안테나와 같이 우리 실생활에 직접 적용할 수 있다면 많은 분야에서 활용이 예상된다. 마이크로스트립 어레이 안테나가 직접 위성수신용 안테나로 활용되려면 우선적으로 광대역 특성이 요구된다. 따라서 본 논문의 목표를 직접 위성수신을 위한 광대역 주파수 대역이 보장되는 안테나 설계기술로 설정하였다. 본 논문에서 제안된 마이크로스트립 안테나는 사각형 패치에 직교하는 두 개의 급전선로에 의해서 급전되도록 하였으며 순차 회전 급전기술로 광대역에서 좋은 축비를 얻을 수 있도록 설계하였다. 사각형 패치는 위성수신 주파수 대역에서 설계되었으며 폭과 길이는 W=L=8.9 mm (<TEX>$0.352{\lambda}o$</TEX>)이며 전체 크기는 <TEX>$250{\times}250mm$</TEX>이다. 제안된 안테나는 기존 급전방식의 안테나에 비해서 1 dB 이상의 축비가 개선되는 것을 실험을 통하여 입증하였다. 안테나의 성능 입증을 위해서 두 개의 <TEX>$8{\times}8$</TEX> 어레이 안테나를 제작하여 실험하였다. 안테나의 최대 이득은 20.8 dB, 사이드로브 레벨 -10 dB 이하를 확인하였다. 본 논문의 안테나를 국내 무궁화 위성수신 시스템에 적용한다면 C/N=6.7 dB의 수신성능이 확보됨을 링크버짓 계산을 통하여 입증하였다. In this paper, the microstrip array antenna is studied to replace the parabolic antenna in the direct satellite reception. A microstrip array antenna has been used in extremely limited area, but if it is applied to practical life like a direct satellite reception antenna, we expect that it will be used in various way. First of all, if we use a microstrip array antenna for a direct satellite reception antenna, it should be guaranteed characteristics of broadband frequency. Therefore, the goal of this paper is designing technique an antenna which guarantees broadband frequency band for a direct satellite reception. In this paper, the proposed microstrip antenna is fed by orthogonal two feed lines to a rectangular patch and a sequentially rotated feeding technique is designed proposed for a good axial ratio in broadband frequency band. The rectangular patch is designed to satellite reception band, and the width and length are W=L=8.9 mm (<TEX>$0.352{\lambda}o$</TEX>) respectively. The antenna's ground plane has dimensions of <TEX>$250{\times}250mm$</TEX>. The experimental results verify that the proposed antenna had the axial ratio of above 1dB broader than that of the conventional feeding antenna. In order to verify the performance, a <TEX>$8{\times}8$</TEX> array having two pairs was fabricated and tested. The maximum gain is 20.8 dB, the sidelobe level confirm less than -10 dB. It is verified by link budget calculation that C/N=6.7 dB can be obtained for domestic use if this proposed antenna is used in Koreasat reception system.

Research on the Circular Polarization Microstrip Array Antenna

A single array element circularly polarized microstrip patch antenna is analyzed based on the theory of cavity mode. Through studying the design of circularly polarized microstrip antenna array, a 96 elements circularly polarized microstrip antenna array is designed and it is optimized by using the Ansoft's HFSS software. After testing of the antenna, we can see that it provides a gain of 22.6dB and has a good axial ratio.

Using Thick Substrates and Capacitive Probe Compensation to Enhance the Bandwidth of Traditional CP Patch Antennas

The simplicity and intuitive design of traditional circularly polarized (CP) patch antennas, such as the truncated corner patch antenna, has led to their widespread popularity. However, they are limited to a narrowband performance on the order of 0.1%-2% for simultaneously good S11 and axial ratio (AR). We will prove theoretically that this is a direct result of the probe reactance hindering the use of thicker substrates to increase the bandwidth. Furthermore, we propose a novel compensation technique to enhance the bandwidth capabilities of these CP patch antennas. Our method inserts a capacitive element, such as an annular gap or parallel plate, in series with the probe inductance to remove its effect. We demonstrate this technique with simulations and measurements to obtain AR- S11 bandwidth capabilities as high as 12.6%. To the authors' best knowledge, this is the first time that capacitive compensation and thick substrates have been jointly employed to enable broadband CP patch antennas.

Dual-band circularly polarized antenna with low observation angle performance enhanced for GNSS applications

A dual-band circularly polarized (CP) antenna with a broadband feeding network that covers the bands of GPS (L1, L2, and L5), Galileo (E5a, E5b, E1, E2, and L1), and GLONASS (L1 and L3) is introduced. This antenna uses the miniaturized feeding network to reduce its size, which is only about 0.26λ × 0.26λ × 0.08λ. It also has another advantage of good axial ratio (AR) and gain performance in the low observation angles. The strip line with three wideband baluns is adopted in the feeding network to achieve good AR bandwidth (more than 50%) and VSWR bandwidth (about 51%). The measured gain is higher than 1 and 3 dBi in the lower and higher bands, respectively. The measured results verify the dual-band CP operation and confirm the validity of this design which meets the requirements of global navigation satellite system applications.

Design of an electrically small circularly polarised turnstile antenna and its application to near‐field wireless power transfer

An electrically small circularly polarised antenna is designed and applied to near-field wireless power transfer as a means of alleviating orientation dependence. The antenna is miniaturised from a λ/2-turnstile antenna by utilising the top loading and multiple folding techniques. A local numerical search is used to determine the optimal antenna dimensions to achieve good axial ratio and impedance matching. The resulting design has a kr of 0.67 and shows good circular polarisation characteristic with a 3% axial ratio bandwidth. The designed antenna is fabricated and its circular polarisation performance is verified in the far field. The power transfer efficiency is then examined in the near field via simulation and measurement. It is shown that the designed circularly polarised antenna is effective in mitigating orientation dependence down to a distance of 0.2λ.

Y형태의 급전 구조를 이용한 편파 변환 재구성 패치 안테나

본 논문에서는 Y자 형태의 급전 구조를 사용한 두 개의 편파 변환 재구성 패치 안테나를 제안하였다. 제안된 안테나는 정사각형 형태의 패치, Y자 형태의 급전 구조, 하나의 핀 다이오드, 다이오드를 동작시킬 DC bias 회로로 구성되어 있다. 구조적인 대칭/비대칭은 두 갈래로 갈라지는 Y자 형태의 급전부 왼쪽 라인에 삽입된 핀 다이오드의 on/off 상태에 의해 결정된다. 제안된 재구성 안테나는 핀 다이오드가 on 상태이면 급전부의 갈라지는 두 마이크로스트립 라인의 길이가 같아지게 되어 안테나는 선형 편파 특성을 나타낸다. 반면에, 핀 다이오드가 off 상태이면 급전부의 갈라지는 두 마이크로스트립 라인 중 한 쪽 라인의 길이가 나머지 한 쪽 라인의 길이보다 상대적으로 짧아지게 된다. 그러므로 안테나는 원형 편파 특성을 나타낸다. 측정 결과로부터 제안된 안테나는 좋은 임피던스 매칭과 축비 특성을 나타내며, 같은 주파수 대역에서 쉽게 편파 변환할 수 있다는 것을 확인할 수 있다. In this paper, a reconfigurable polarization patch antenna that uses a Y-shaped feed is proposed. The proposed antenna consists of a square patch, a Y-shaped feeding structure, a PIN diode, and a bias circuit for diode operation. The structural symmetry/asymmetry of the feeding structure is determined by the on/off operation of the PIN diode that inserted into the side of one of the lines of the Y-shaped feeding structure. For the proposed reconfigurable antenna, the two microstrip lines of the feeding structure have the same length when the PIN diode operates in the on state, and the antenna exhibits linear polarization(LP). On the other hand, when the PIN diode operates in the off state, the length of one side line of the feeding structure is relatively shorter than that of the other line. Therefore, the antenna exhibits circular polarization(CP). From the measurement results, it is found that the proposed antenna exhibits good impedance matching and axial ratio. In addition, polarization switching can be easily achieved in the same operating band.

A Coplanar Waveguide Fed Rectangular Reconfigurable Patch Antenna with Switchable Strips for Polarization Diversity

A compact single feed rectangular patch antenna with reconfigurable circular polarization has been proposed in this paper. The basic antenna structure is a rectangular patch of dimensions 10 mm x 15 mm printed on a thin FR4 substrate of thickness 3 mm. Two rectangular strips are connected through switches at sideways of the main patch to get polarization diversity. The polarization of the proposed antenna can be reconfigured between left hand circular polarization (LHCP) and right hand circular polarization (RHCP) by the current path, which is changed by operating the switches in ON and OFF modes. The antenna is designed and simulated using IE3D MoM based electromagnetic simulator. The simulated results show good return loss, radiation pattern, axial ratio and acceptable gain at the operating frequency. The antenna has around 15 % effective impedance bandwidth over 4.0 GHz - 4.8 GHz frequency band at a maximum gain of 3.0 dBi with polarization diversity. Defence Science Journal, Vol. 64, No. 1, January 2014, DOI:10.14429/dsj.64.4807

A Circularly Polarized Small-Size Microstrip Antenna using a Cross Slot with Enhanced Bandwidth &amp; Gain

In the recent years the development in communication systems requires the development of low cost, minimum weight, low profile antennas that are capable of maintaining high performance over a wide spectrum of frequencies. This technological trend has focused much effort on the design of a Microstrip patch antenna. A new, circularly polarized small-size microstrip antenna using a proximity coupled feed method is proposed. A simple configuration based on a cross slot with unequal slot lengths on a circular patch is adopted to realize a small-size element antenna. The measured results verify the circular polarization, and the antenna radius was reduced by about 22% by using the slot lengths which are nearly equal to the diameter of the circular patch antenna. Good impedance and axial ratio characteristics have been obtained.

Design for Triple Band Patch Array Antenna with High Detection Ability

This paper proposes a theoretical analysis of hidden device detection and a design of multiband circular polarization patch array antenna for non-linear junction detector system application. A good axial ratio of circular polarization patch antenna is realized by a new approach that employs inclined slots, two rectangular grooves and a truncated ground for the conventional antenna. A good axial ratio of the 1.5 dB lower is measured by having an asymmetric gap distance between the ground planes of the coplanar waveguide feeding structure. The common ground plane of the linear array has an optimum trapezoidal slot array to reduce the mutual coupling without increasing the distance between the radiators. The higher gain of about 1 dBi is realized by using the novel common ground structure. The measured return loss, gain, and axial ratio of the proposed single radiator, as well as the proposed array antennas, showed a good agreement with the simulated results.

Polarisation diversity antenna with asymmetrical Y‐shaped feed structure

A reconfigurable antenna with polarisation diversity is proposed. The proposed antenna consists of a square radiating patch and a switchable Y-shaped feed structure. The radiating patch is fed by the switchable Y-shaped feed line to dynamically change the polarisation state. The novel structure described here enables matched input optimisation for both polarisations. Low cross-polarisation levels in the linear state and good axial ratios in the circular state are observed.

Design for High Gain Spiral Antenna by Added Conical Cavity Wall

This paper describes a design for a spiral antenna with a conical wall to obtain the high gain. The gain and the axial ratio of the spiral antenna were improved by a new design that included a conical wall and an optimized Archimedean slit on the ground plane in a conventional antenna with a circular cavity wall and a 4.5-turn slit. A gain improvement of 9.5 dBi higher and a good axial ratio of 1.9 dB lower were measured by the added conical wall and the newly designed slit from the current distribution control on the ground plane, respectively. The measured return loss, gain and axial ratio of the proposed antenna showed a good agreement with the simulated results. The proposed antenna will be applied to a non-linear junction detector system.

Novel design of strip line L-shape probe-fed wideband metallic contact stacked patch antenna for GNSS application

A novel design of compact circularly polarized metallic contact annular stacked patch antenna has been proposed for global navigation satellite system in this paper. In order to obtain wideband characteristics, broadband 90° hybrids have been used as a secondary network. As a result, the antenna has an effective bandwidth of 87% from 0.85 to 2.16 GHz for VSWR < 2, and 62.4% from 0.97 to 1.85 GHz for AR < 3 dB respectively, which is sufficiently enough to operate for the satellite navigation frequencies including GPS, GLONASS, Galileo and Compass (1100–1600 MHz). The designed antenna can provide stable gain bandwidths, broad beam width and good axial ratio at low elevation by introducing metallic contact annular stacked patch structure. The designed antenna occupies a compact size of 100 mm × 100 mm × 13 mm.

Novel Design of Broadband Strip Lines Fed Patch Antenna for GNSS Application

ABSTRACTNovel design of stacked circularly polarized strip lines fed patch antenna has been proposed for global navigation satellite system in this article. The antenna has been designed to operate for the satellite navigation frequencies including GPS, global navigation satellite system, Galileo and Compass (1100—1600 MHz). Three normal Wilkinson power dividers are connected together acting as the feeding networks. As a result, the antenna has a 57.6% 10‐dB return loss bandwidth from 1.05 to 1.9 GHz and 42.9% 3‐dB axial ratio bandwidth from 1.1 to 1.7 GHz, respectively. Crossed slots are cut on the radiating patch to increase the antenna gain. The designed antenna in this article can acquire broad beam width and good axial ratio at low elevations. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2062–2066, 2013

Novel design of multilayer wideband shorted annular stacked patch antenna for GNSS application with dual layer strip lines fed

Novel design of compact circularly polarized shorted annular stacked patch antenna has been proposed for global navigation satellite system in this study. The antenna has been designed to operate for the satellite navigation frequencies, including GPS, GLONASS, Galileo and Compass (1100–1600 MHz). Dual-layer strip lines that being composed of one broadband 180° hybrid and two wideband 90° hybrids are introduced as feeding network. As a result, the antenna has a 50.8% 10-dB return loss bandwidth from 1.1 to 1.85 GHz, and 45.5% 3-dB axial ratio bandwidth from 1.07 to 1.7 GHz, respectively. The designed antenna occupies a compact size of 70 mm × 70 mm × 28.5 mm. In this study, shorted annular stacked patch is introduced to obtain stable gain bandwidth, broad beam width characteristics, and good axial ratio at low elevation.

Modified Dual-Band Stacked Circularly Polarized Microstrip Antenna

A novel high-performance circularly polarized (CP) antenna is proposed in this paper. Two separate antennas featuring the global positioning system (GPS) dual-band operation (1.575 GHz and 1.227 GHz for L1 band and L2 band, resp.) are integrated with good isolation. To enhance the gain at low angle, a new structure of patch and two parasitic metal elements are introduced. With the optimized design, good axial ratio and near-hemispherical radiation pattern are obtained.

WIDEBAND SHORTED ANNULAR STACKED PATCH ANTENNA FOR GLOBAL NAVIGATION SATELLITE SYSTEM APPLICATION WITH COMPACT SIZE AND BROAD BEAMWIDTH CHARACTERISTICS

A compact circularly polarized shorted annular stacked patch antenna has been proposed for global navigation satellite system (GNSS) in this paper. The antenna has been designed to operate for the satellite navigation frequencies including GPS, GLONASS, Galileo and Compass (1100MHz{1600MHz). In order to obtain wideband characteristics, broadband 90 - hybrids have been used as a secondary network. The designed antenna has a 73.7% (10-dB) return loss bandwidth from 0.9GHz to 1.95GHz, and 60.1% 3-dB axial ratio bandwidth from 0.96GHz to 1.8GHz, respectively. Shorted annular stacked patch structure is incorporated into the antenna design helping to obtain stable gain bandwidth, broad beamwidth characteristics and good axial ratio at low elevation. The designed antenna occupies a compact size of 100mm £ 100mm £ 15:5mm.

Improvement of a Circular Microstrip Antenna Excited by Four Feeds and Suspended with Artificial Magnetic Conductors

The proposed antenna is a circular microstrip structure excited by four feeds and suspended with artificial magnetic conductors (AMCs). The multifeed circular microstrip antennas can generate a high circularly polarized performance by using a different feed arrangement. AMC structures with a square, circular, or octagonal patch on a unit cell are designed and applied to circular microstrip patch antennas for the enhancement of antenna performance. It is found that simulated results of the proposed antenna are well suited. The properties of wide beamwidth with good axial ratio can be achieved when applying the proposed AMC structures to circular microstrip antennas. The antenna prototype was fabricated to validate simulated results.

Dual-Band Circularly Polarized Annular-Ring Microstrip Antenna for GNSS Applications

A dual-band circularly polarized antenna fed by four apertures that covers the bands of GPS (L1, L2, L5), Galileo (E5a, E5b, E1, E2, L1), and GLONASS (L1, L3) is introduced. A lotus-shaped aperture is added to optimize the coupling between the microstrip lines and the rings. Three wideband planar baluns are used to achieve good axial ratio (lower than 2.1 dB in both bands) and VSWR (41.2%). The measured results of the annular-ring microstrip antenna show good performance of a dual-band operation, and they confirm the validity of this design, which meets the requirement of Global Navigation Satellite System (GNSS) applications.

A microstrip antenna design with multislots embedded into the ground plane for circular polarization

A single probe-fed square microstrip antenna with two pairs of asymmetric narrow slots loaded into the ground plane for circular polarization (CP) is studied. To allow a simple fine tuning CP mechanism, the method of loading an additional square slot into the center of the ground plane is introduced into this proposed antenna. By tuning the overall-size of this center square slot, the CP frequency can be easily tuned with minor effects on the CP performances. Furthermore, good axial ratio (AR) value of around 0.5 is also measured at 1575 MHz, which is suitable for GPS operation. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2013.