基模螺旋天线的研究

本文提出了一种计算基模螺旋天线的新方法.该方法采用螺旋线段对基模螺旋天线进行划分,只需少量分段就可用矩量法对其进行精确模拟分析.文中求出了螺旋天线上的电流分布和远场方向图,与直线段模拟计算结果吻合良好.求阻抗矩阵 Z时,利用螺旋天线的对称性和周期性,只需求出一小部分元素就可得到Z 矩阵的其它元素的值.该方法分段数少,使得计算时间和计算所需存储量大大减小,计算速度和精度显著提高.     

A new moment method for the fast and accurate analysis of normal mode helical antennas

In this letter, a new moment method using helical segments is presented to model Normal Mode Helical Antenna (NMHA). Using this method, the NMHA can be modeled by a few segments. The current distributions and radiation patterns of some NMHAs are calculated. A comparison is made between results obtained using this helical segment algorithm and a linear segment algorithm, and the results of the two algorithms agree fairly well. When calculating the impedance matrix [Z], all the elements of the matrix can be obtained by only calculating a few elements with the application of the symmetric and periodic characteristics of the NMHA. Therefore, the CPU time and the memory storage are significantly reduced, with the accuracy and speed enhanced.     

Dual-band planar inverted F antenna for GSM/DCS mobile phones

A compact dual-band planar inverted F antenna suitable for the application as a global system for mobile communication/digital communication system (GSM/DCS) dual-band mobile phone internal antenna is proposed and implemented. The proposed antenna has three resonant elements, two meandered metallic strips of slightly different lengths and one nearly-rectangular patch, which are printed on a supporting FR4 substrate and arranged in a compact configuration. These three resonant elements share a common shorting pin, and for the GSM (890-960 MHz) operation, the proposed antenna is operated with the two meandered strips both resonated as a quarter-wavelength structure, leading to a wide bandwidth formed by two resonant modes. For the upper band of the proposed antenna, three resonant modes are generated, two from the second higher-order modes of the two meandered strips and one from the nearly-rectangular patch, leading to a wide bandwidth covering the DCS band (1710-1880 MHz). The antenna design and experimental results are presented.     

Broadband rectangular microstrip antenna with pair oftoothbrush-shaped slots

A novel broadband design of a probe-fed rectangular microstrip antenna with a pair of toothbrush-shaped slots embedded close to the nonradiating edges of the patch is presented. The proposed broadband design is achieved by the excitation of two adjacent resonant frequencies of the TM₁₀ and TM_δ0 modes (1<δ<2), to obtain a wide operating bandwidth. An antenna bandwidth as large as ~2.6 times that of a conventional rectangular microstrip antenna has also been obtained. Derails of the proposed design and experimental results are presented     

A Circuit-Theoretic Approach to the Design of Quadruple-Mode Broadband Microstrip Patch Antennas

A novel method for the design of broadband patch antennas is described. The approach taken is to broadside couple two dual-mode patch antennas, resulting in a quad resonance antenna. The equivalent circuit of the antenna is similar to that of microwave filters, thus filter design techniques maybe employed to synthesize the antenna to obtain maximum return-loss bandwidth. This is the first time an increase in the bandwidth is achieved on a relatively thin substrate antenna as a result of coupling four resonant modes using two stacked circular microstrip patches. Electromagnetic simulation and measured results demonstrate bandwidth improvement of over four times that of a single-mode design.     

蝶形微带天线的全波分析与宽带设计

介绍了蝶形微带贴片天线的一种全波分析方法－矩量法,与多端网络法相比,其适应范围更广。然后介绍了展宽天线频带的一种设计方法。通过不对称馈电方式,激励起两个相近频率的模式,从而使微带天线驻波比带宽获得明显展宽。测试结果与计算结果相当吻合,证实了数值分析与设计方法的有效性。     

一种槽线扰动的基片集成波导双模滤波器

该文提出一种新型小型化基片集成波导(SIW)双模滤波器。通过使用正交的输入输出馈线,和一段倾斜的槽线来扰动腔体的两个简并模,滤波器能产生两个传输零点(TZ)。采用该方法设计了一个中心频率为15 GHz,带宽为350 MHz的基片集成波导双模滤波器。该滤波器结构简单,成本低廉,易于加工。测试结果和仿真结果吻合,较好地验证了设计的可行性和有效性。     

Circularly-Polarized Wide Slot Antenna Loaded With a Parasitic Patch

A design is described of a broadband circularly-polarized (CP) slot antenna. A conventional annular-ring slot antenna is first analyzed, and it is found that two adjacent CP modes can be simultaneously excited through the proximity coupling of an L-shaped feed line. By tuning the dimensions of this L-shaped feed line, the two CP modes can be coupled together and a broad CP bandwidth is thus formed. The design method is also valid when the inner circular patch of the annular-ring slot antenna is vertically raised from the ground plane. In this case, the original band-limited ring slot antenna is converted into a wide-band structure that is composed of a circular wide slot and a parasitic patch, and consequently the CP bandwidth is further enhanced. For the patch-loaded wide slot antenna, its key parameters are investigated to show how to couple the two CP modes and achieve impedance matching. The effects of the distance between the parasitic patch and wide slot on the CP bandwidth and antenna gain are also presented and discussed in details.      

Calculation of relative single-polarisation bandwidth of side-pit fibres

A simple and accurate method to calculate the normalised cutoff frequencies of the two fundamental modes of a side-pit fibre is given. The method can be used to design side-pit fibres with large relative single-polarisation bandwidth.     

Frequency-adjustable circularly polarised dielectric resonator antenna with slotted ground plane

Circularly polarised (CP) dielectric resonator antennas (DRAs) with a slotted ground plane are proposed. The proposed CP design is achieved by embedding two pairs of unequal slots in the finite ground plane of the feed substrate, which results in the excitation of two near-degenerate orthogonal modes and leads to CP radiation. For the proposed design, a large CP bandwidth, determined from 3 dB axial ratio, as high as 2.7% is also obtained. The resonant frequency can be tuned by changing the slot length. This proposed design is applicable to DR antennas where post-manufacturing trimming is required. Details of the proposed designs and experimental results of the constructed prototypes are presented.     

一种通带可控的双频SIW滤波器设计

提出了一种通过加载T形槽实现双频可控的基片集成波导带通滤波器。滤波器的双频特性由SIW腔内对称的T形槽线谐振器微扰TE101和TE102模得到。通过改变槽线谐振器的物理尺寸可以实现对滤波器两个通带中心频率的灵活控制。为了验证上述方法的可行性,设计了一个中心频率为3.77 GHz和9.27 GHz的双频滤波器。实测得该双频滤波器两个通带的回波损耗优于11 dB,在3.77 GHz时插入损耗为0.8 dB,第一通带的相对带宽可达13%。仿真和测试结果吻合较好,证实了设计方法的有效性。     

A Tunable Metamaterial Frequency-Selective Surface With Variable Modes of Operation

A reconfigurable miniaturized-element frequency-selective surface (FSS) is presented in this paper. A standard waveguide measurement setup is used to evaluate the performance of the design. The proposed FSS consists of two periodic arrays of metallic loops, with the same periodicity, on either side of a very thin dielectric substrate. The tuning of the reconfigurable surface is shown numerically to be possible by incorporating tuning varactors into the structure. Using varactors on both layers, a reconfigurable frequency response is achieved, which has two modes of operation: bandstop and bandpass. In addition to two completely different modes of operation, the center frequency, as well as the bandwidth of the response can be tuned independently. Frequency tunability with a constant bandwidth over 3–3.5 GHz is shown. A bandwidth tuning at a fixed center frequency is also demonstrated. Simulation results are verified experimentally by fabricating prototypes of the design at $S$-band loaded with lumped capacitors. To demonstrate the tunability, different pairs of fixed-valued capacitors, as opposed to varactors, are used in a waveguide measurement setup to avoid difficulties associated with biasing varactors in the waveguide.      

Ferrite‐based wideband circularly polarized microstrip antenna design

In this paper, a wideband, circularly polarized patch antenna is proposed that leverages the unidirectional resonant modes of a circular patch mounted on top of a grounded dielectric‐ferrite substrate. The proposed antenna is fed via the proximity coupling method and several parasitically coupled patches are placed on a dielectric superstrate to enhance the impedance bandwidth of the antenna. The resonant modes of the structure rotate only in the clockwise or counter clockwise directions. In the frequency range where the effective permeability of the ferrite layer is negative, the resonance frequencies of these modes differ significantly, which produces a large axial ratio (AR) bandwidth. For the proposed antenna, the numerical results show the 10 dB impedance bandwidth to be around 44% and the 3 dB axial ratio bandwidth to be higher than 64%.     

一种宽带蝶形印刷天线的研究

文中对一种新颖的具有宽频带特性的蝶形印刷天线进行了研究,给出了这种天线理论分析方法和实验测试结果.通过不对称馈电方式,激励起两个相近频率的模式,从而使蝶形印刷天线驻波比带宽获得明显展宽.测试结果与计算结果相当吻合,证实了数值分析与设计方法的有效性.     

Broadband circularly polarised crosspatch- loaded square slot antenna

A new design of a circularly polarised square slot antenna loaded with a cross patch is presented. A cross patch inclined diagonally with respect to the square slot is placed at the centre of the square slot. By choosing proper dimensions of the cross patch, two orthogonal resonant modes with a 90deg phase difference for circular polarisation can be excited and feed the square slot antenna using a 50 Omega CPW with a protruded signal strip. 10 dB return loss bandwidth of 846 MHz (39.6%) and 3 dB axial ratio bandwidth of 240 MHz (12.4%) for the proposed antenna are achieved. Gain variation within the CP bandwidth is observed to be less than 1 dB     

（英）基于新型双模圆谐振腔的高选择性毫米波滤波器

提出了一种新颖的高选择性毫米波带通滤波器及其设计方法.在圆谐振腔的侧壁加入槽型微扰结构,通过调节微扰小槽的角度可以控制滤波器带外传输零点的位置,从而实现了带宽可调、高选择性的双模圆谐振腔带通滤波器.根据该滤波器结构、理论分析和仿真设计基础,研制了在V波段滤波器样品并进行了测试.实验结果与方正吻合得良好.与传统双模圆腔滤波器相比,所提出的滤波器不需要额外的调节结构,其设计方法简单,选择特性高,结构紧凑,具有一定的工程价值用于高性能平面化毫米波滤波器的设计.     

Internal quad-band printed antenna for PDA phone

A quad-band inverted-F antenna for PDA-phone applications is presented. The proposed antenna measures only 46 times 12 times 0.8 mm. It has an inverted-L element combined with a meander-line branch to excite two resonant modes. By using a matching element, the bandwidth can be broadened to cover GSM850/GSM900/DCS/PCS bands. Simulation was performed by HFSS to optimally design the antenna, and a practical structure was fabricated to verify the simulation results. The antenna parameters were measured and are presented to validate the proposed antenna.     

A Method of Analysis of Symmetrical Four-Port Networks

An analysis of four-arm symmetrical networks such as a branched directional double stub coupler or the hybrid ring (rat race) is presented. The input wave is broken into an even and an odd mode and the vector amplitude out the various arms is computed from the sums or differences of the reflection or transmission coefficients for the two modes. A zero decibel directional coupler is described and its possible use as a duplexer is proposed. The design of multiple stub directional couplers for any degree of coupling is discussed. A method of computing the bandwidth of all these couplers is outlined, and the bandwidth curves, the power out the various arms with respect to frequency of the zero decibel coupler, are computed. A tabulation is made for six different 3 db couplers (even-power split) and their standing wave ratio, evenness of power split and isolation of the fourth arm as a function of frequency assuming perfect performance at the band center.     

基于等效磁表面的层叠型介质谐振器天线

提出了一种基于等效磁表面的层叠型介质天线,同时具有宽带和高增益等特点。设计采用两片高介电常数的薄介质片,构造出两个等效磁表面,结合金属地的等效电表面,可以在“电-磁"以及“磁-磁"的边界条件中获得两个独立的TE^y₁₁₁ 模式。通过合并这两个模式可以有效拓展天线的工作带宽,同时,等效磁表面的引入还可以提高天线的增益。天线的仿真和测试结果一致性良好,其|S11|<-10 dB 的相对带宽约为36%,最大增益在6.3 GHz 处达到8.4 dBi。另外,该天线的辐射单元均由低损耗的介质构成,辐射效率高,使其在未来无线通信系统中具备一定的应用前景。     

A 0.4–2.3 GHz broadband power amplifier extended continuous class-F design technology

A 0.4–2.3 GHz broadband power amplifier (PA) extended continuous class-F design technology is proposed in this paper. Traditional continuous class-F PA performs in high-efficiency only in one octave bandwidth. With the increasing development of wireless communication, the PA is in demand to cover the mainstream communication standards’ working frequencies from 0.4 GHz to 2.2 GHz. In order to achieve this objective, the bandwidths of class-F and continuous class-F PA are analysed and discussed by Fourier series. Also, two criteria, which could reduce the continuous class-F PA’s implementation complexity, are presented and explained to investigate the overlapping area of the transistor’s current and voltage waveforms. The proposed PA design technology is based on the continuous class-F design method and divides the bandwidth into two parts: the first part covers the bandwidth from 1.3 GHz to 2.3 GHz, where the impedances are designed by the continuous class-F method; the other part covers the bandwidth from 0.4 GHz to 1.3 GHz, where the impedance to guarantee PA to be in high-efficiency over this bandwidth is selected and controlled. The improved particle swarm optimisation is employed for realising the multi-impedances of output and input network. A PA based on a commercial 10 W GaN high electron mobility transistor is designed and fabricated to verify the proposed design method. The simulation and measurement results show that the proposed PA could deliver 40–76% power added efficiency and more than 11 dB power gain with more than 40 dBm output power over the bandwidth from 0.4–2.3 GHz.