Wideband compact antenna for K-band applications

A compact coupled microwave active antenna is presented. This antenna is proximity fed, and consists of a square radiating element array on a polymer dielectric layer. The compactness of the antenna is obtained through technological optical processes and the parasitic patch phenomenon which increases the bandwidth     

Aperture coupled to stripline antenna element for integrated antenna arrays

A new stripline-fed aperture coupled antenna element is proposed. An additional slot in a ground plane allows achievement of efficient electromagnetic coupling with the radiating element and good return loss of the antenna fed by a stripline. The described radiating elements can be easily integrated with a feeding network designed in the most commonly used stripline technique when a large antenna array is to be developed.     

一种新型宽带双极化低剖面复合式阵列天线

提出了一种利用多种形式的辐射贴片阵元组成的复合式阵列天线。阵元采用了多种形式的馈电方法。部分阵元和馈电微带线直接连接馈电,其他阵元和馈电微带线采用电磁耦合进行馈电。通过优化辐射贴片的形状、对应的馈电方法、辐射贴片连接端的阻抗调节块、阵列单元之间的阻抗调节段,在宽频带内不但获得了良好的阻抗特性,也实现了期望的赋形辐射方向图。测试结果表明,该阵列天线高度小于中心频率的0.06个波长,相对阻抗带宽(驻波比小于1.45)和辐射带宽分别超过23%和17%。     

Low-Cost Broadband Circularly Polarized Printed Antennas and Array

This paper presents the design, simulation, and measurements of two low-cost broadband circularly polarized (CP) printed antennas: an element and an array at 2 GHz. To realize the broadband circularly polarized antenna element, a circular microstrip patch is electromagnetically coupled by crossed slots cut in the ground plane, which is fed by an L-shaped microstrip feed. Two orthogonal modes in the patch are excited by using the crossed slots, and a single L-shaped feed provides a 90deg phase shift between two orthogonal slots. The antenna element achieves a 9.6% bandwidth for an axial ratio (AR) below 3 dB and a voltage standing wave ratio (VSWR) below 1.5. To further improve the performance, a sequentially rotated feed network is designed for a 2 times 2 array. The axial ratio value of the array is below 3 dB within a 27.2% bandwidth, from 1.75 GHz to 2.3 GHz. The return loss is above 10 dB within a 41% bandwidth, from 1.62 GHz to 2.45 GHz. Details of the proposed antenna element and the array design are described, and both the simulation and the experimental results are presented and discussed.     

Compact UWB monopole for multilayer applications

A novel compact, dual-layer UWB monopole antenna is presented. This low profile ultra-wideband antenna is fed by a 50 /spl Omega/ shielded strip-line with an array of metal vias making the conducting walls. A printed disc monopole with a circular cut is the radiating element. The dual-layer, shielded strip-line feed allows for integration in multilayer technologies. The ultra-wideband, monopole characteristics of the antenna are confirmed experimentally     

A novel amplifying antenna array using patch-antenna couplers-design and measurement

This paper proposes a novel amplifying antenna array using the patch-antenna coupler formed by placing one or two open-ended microstrip lines (coupled lines) near and along the nonradiating edge(s) of a patch antenna. An X-band five-element array with broadside 25-dB Chebyshev radiation is demonstrated. When the input signal is fed to the center element, with most of the power radiating from the antenna, part of it is tapped to the coupled lines, amplified by an FET amplifier, and fed to the next antenna element. This process is repeated after all the antenna elements are fed with suitable power. The amplitude distribution of the fields radiated from the antennas is controlled by the coupling coefficient from the patch to the coupled line, which, in turn, is governed by the coupling length and gap between the patch and line. The measured return loss of the designed five-element array is -27 dB at the center frequency of 10 GHz with 2% 10-dB bandwidth. The radiation pattern possesses a transmitting gain of 15.9 dB, a half-power beamwidth of 17/spl deg/, and a sidelobe level of -22 dB.     

Design, optimization, and validation of a planar nine-element Quasi-Yagi antenna array for X-band applications [Antenna designer's Notebook]

A planar antenna array, based on nine identical quasi-Yagi elements, is presented in this paper. Contrary to conventional designs, the feeding network is composed of three-way power dividers, which are carefully designed in order to provide synchronized output signals over a wide frequency range. The use of spline-shaped microstrip lines suppresses coupling effects by parallel lines. Thus, signal distortions within the feeding network are minimized. Compared to conventional designs with eight elements, the additional antenna element will enhance the gain of the array, which is between 10.5 dBi and 13 dBi in the X band. The input return loss of the antenna array is below -15 dB over most parts of the relevant spectrum, with a total bandwidth of 45%. The planar antenna array is well suited as a radiating element in linear phased arrays for multifunction radars, including SAR and MTI. Additionally, the suitability of this antenna for phased-array applications is studied by an experimental setup consisting of five antenna plates.     

A theoretical study of a mulit-element scanning feed system for a parabolic cylinder

This paper is a theoretical investigation of a method of scanning a beam of an antenna consisting of a fixed reflector and an array of elements illuminating the reflector by appropriately controlling the phase and amplitude of the signal radiating from each element. For the purpose of determining the feasibility of such a systems the two-dimensional problem is explored where a specific antenna geometry and an element radiation pattern are assumed. It was found that although the system exhibits similar performance to a system with a single radiating element when radiating a beam on axis, it could be scanned some eight beamwidths off axis without significant deterioration in characteristics. Interestingly, it was discovered that there is a separation (about0.7lambdain this case) between the feed elements where the sidelobes become dramatically high, analogous to grating lobes in a phased array.     

Use of a spreadsheet program in an antenna design application

A method of using a spreadsheet program in antenna design is presented. The method is applied to the design of a vertical array of two radiating elements where each element is a circular arrangement of four half-wave dipoles, each of which is tilted with respect to the horizontal. Results are presented.     

双频段双极化共孔径阵列馈源反射面天线设计

介绍了一种新型Ku/Ka双频段双极化共孔径阵列馈源偏馈抛物柱反射面天线的设计。在双频段双极化共孔径阵列馈源设计中,Ka波段采用裂缝波导阵,并且位于共孔径馈源阵列的下层,双极化Ku波段采用微带贴片天线、位于共孔径阵列馈源的上层。文中给出了该双频段双极化共孔径阵列馈源的设计及测试结果,并将该测试结果代入偏馈抛物柱反射面天线中在FEKO软件平台上进行了半实物仿真,仿真结果表明,该双频段双极化共孔径阵列馈源偏馈抛物柱反射天线实现了如下设计目标:Ku波段双极化水平面扫描范围为±17°,两个主面副瓣电平优于-30dB,Ka波段水平面扫描范围为±10°,两个主面的副瓣电平优于-30dB,双频段双极化两个主面的波瓣宽度和波束指向完全匹配。     

Dual polarized stacked SSFIP array antenna in C-band for beam-pointing

This paper presents the design and development of a wideband dual polarized planar array antenna of 4 × 6 elements in C-band with a centre frequency of 5.3?GHz. The radiating element is of stacked strip slot foam inverted patch (SSFIP) configuration. The complex excitation coefficients of the antenna have been chosen in order to achieve a fixed beam-pointing by 10° and side-lobe level better than ?15?dB. The array antenna offers a VSWR bandwidth of 20% for a VSWR ratio of 2:1. The simulated and measured antenna parameters are presented.     

Array Antenna With Increased Element Separation Based on a Fabry–PÉrot Resonant Cavity With AMC Walls

A new method is presented for increasing the separation between the radiating elements of a 1-D array antenna by incorporating it into a Fabry-Perot type resonant cavity with artificial magnetic conductor (AMC) walls. The AMC walls create a more uniform distribution of field within the cavity and, moreover, eliminate diffracted fields. The concept is demonstrated via 3-D full-wave simulations as well as experimental measurements for a prototype antenna. Comparison between an antenna with AMC walls and an identical reference antenna, without walls, shows a reduction in the sidelobe level. An array element separation of 2lambda is achieved whilst maintaining good radiation performance. The performance of the proposed structure is also compared to that of an antenna incorporating PEC walls. Finally, the effect of the sidewall and central AMC walls are considered separately in order to isolate their corresponding effect on the antenna performance.     

Radiating and scattering analyses of a slot-coupled patch antennaloaded with a MESFET oscillator

In this paper, radiating and scattering analyses of a slot-coupled patch antenna loaded with a MESFET oscillator at free-running and injection-locked states are presented. This arrangement is a basic module of an injection-locked active array. With a small injection signal applied directly to the oscillator in a transmission-type mode or indirectly through a patch antenna to the oscillator in a reflection-type mode, the oscillator loaded antenna then becomes an injection-locked active antenna (ILAA) within the locking range. Simulation results yield the oscillating frequency and radiating power at the free-running state and the locking range and radiating power at the injection-locked state. Both radiating and scattering analyses are performed in a unified approach for the transmission-type and reflection-type operation modes of ILAA. Experiments show the validity of the developed theoretical analyses. These results can be applied in the ILAA array design     

Dielectric cover effect on rectangular microstrip antenna array

A theoretical model to analyze a covered rectangular antenna with an arbitrary dielectric constant superstrate is developed. The antenna is simulated by the radiation of two magnetic dipoles located at the radiating edges of the patch. The Green's function of an elementary magnetic dipole in a superstrate-substrate structure, utilizing spectral-domain analysis, is formulated, and the surface-wave and radiation field are computed. An improved transmission line model, which considers the stored energy near the radiating edges and the external mutual coupling, is used to compute the input impedances and radiation efficiency. Design considerations on the superstrate thickness and its dielectric constant are discussed. Experimental data for a single element and a 4×4 microstrip array is presented to validate the theory     

A high-gain 58-GHz box-horn array antenna with suppressed gratinglobes

A low-profile high-gain antenna array of box horns for the frequency band 57.2-58.2 GHz is presented. The antenna consists of 256 radiating elements divided into two subgroups of 128 elements fed by a rectangular waveguide feed network. The radiating elements are fed in parallel and the waveguides are connected with T-junctions. The matching of the T-junctions is improved with a matching pin and a splitter. Because of the waveguide feed network, the element spacing is larger than one wavelength, which causes grating lobes. The grating lobes and sidelobes in the H-plane have been suppressed by the use of a combination of subarrays, a special characteristic of the box horn, and an array amplitude tapering. The measured sidelobe levels in the H-plane are below -30 dB at angles larger than 8° from boresight. A gain higher than 35.7 dBi and a return loss higher than 14.4 dB have been measured for the antenna over the band 57.2-58.2 GHz     

Broadband low-cost planar sector antenna element for WLAN applications

A novel planar antenna element for applications in sector antennas is proposed. The antenna element consists of three patches coupled both electromagnetically and through the feeding network to ensure 90deg beamwidth in a wide frequency range. A suspended microstrip technique has been used to ensure simultaneously low production costs and low losses within the feeding network. The designed antenna element operates within a frequency range of 5.1-5.9 GHz.     

Design and experimental investigation of a multibeam integrated reflector antenna of the millimeter wave band

A multibeam integrated reflector antenna operating in the millimeter wave band is considered. The antenna consists of a radiating array, a planar mirror, and a multichannel feed. The results of simulation of a radiating array of slots in a metal screen are presented. The array is manufactured on the basis of a medium with forced refraction, including a double-slot array, which can radiate along the normal to the array plane. Operation of the array in the multibeam mode is analyzed. It is shown that application of a medium with forced refraction increases the array aperture efficiency in this mode. The results of the design of a planar two-layer mirror are presented and the mirror’s quality indices are estimated. A multichannel radiator designed as an array of planar H-plane horns is studied. The results of simulation of such a radiator with the help of an approximate technique and numerical solution of an electromagnetic problem are considered. The design of the multibeam antenna and its experimental characteristics are presented.     

Wideband single layer microstrip antenna for array applications

A wideband single layer microstrip antenna, fed by two different networks, is presented. A bandwidth of ~15% for SWR<2 is obtained. As its dimensions are the same as those of a conventional 2×2 sub-array, this radiating element can be used in array configuration     

Electromagnetic band gap coupled tri-notched miniaturized ultra-wideband antenna loaded with slot and parasitic strip

An electromagnetic band gap (EBG) coupled miniaturized tri-notched printed ultra-wideband (UWB) monopole microstrip antenna having dimensions of 22 mm × 26 mm × 1.6 mm loaded with a slot in radiating patch and a parasitic strip in the ground plane has been presented. The proposed structure incorporates a square-shaped metallic radiating patch with a square EBG structure adjacent to the microstrip feed line, a U-shaped meandered slot over the radiating element, and a U-shaped parasitic resonator at the ground plane beneath the radiating element, to reject the C-band satellite downlink (3.7 to 4.2 GHz), WLAN frequency band (5.15 to 5.85 GHz), and X-band satellite downlink (7.25 to 7.75 GHz) frequency bands, respectively. The designed antenna operates in the frequency range from 3 to 11.1 GHz, with an impedance bandwidth of 8.1 GHz and a percentage bandwidth of 114%. Modification steps incorporating into the reference antenna to achieve the desired design objectives have been discussed, along with parametric studies. The proposed design has been simulated using Ansys HFSS, and measurement has been taken using standard measurement technique and compared with the simulated results.     

一种快速测量与故障检测相控阵天线的新方法

介绍了一种测量相控阵天线的新方法——换相测量法,给出了该方法的数学模型及其基于最优配相控制的解。由于使用该方法时要求被测天线和探头均固定不动,仅要求对天线各单元的配相进行控制,故实际上这是用电扫描方法来代替传统的机械扫描方法。该方法应用了单元的阵内方向图等天线先验知识。最后模拟了应用该方法对相控阵天线进行测量和故障检测的全过程。模拟结果表明,该方法是正确的,快速有效的。