Crossed dipole antenna with switchable circular polarisation sense

A crossed dipole antenna with a reconfigurable circular polarisation (CP) is proposed. This antenna consists of a pair of L-shape elements with λ_g/4 phase delay lines and DC bias circuits for pin diodes. As the state of the pin diodes mounted between the feeding points and the L-shape elements is changed, the phase sequence of the crossed dipole can be varied. The CP sense of the proposed antenna can be switched with excellent electrical controllability.     

Metamaterial-based compact zeroth-order resonant antenna

A metamaterial-based compact one-unit-cell antenna realised on a microstrip line is presented. The size of the proposed antenna is only 6 X 13.5 mm (or 0.05 X 0.13 λ₀) at 2.7 GHz owing to zeroth-order resonance. The design procedures with closed-form solutions are provided using transmission line theory considering radiation loss. The measured antenna bandwidth is 15 MHz and total gain is 1.22 dBi.     

基于多节SIRs的新型四通带滤波器设计

提出了一种基于多节1/2波长SIRs的具有通带可控的紧凑型四通带滤波器。该滤波器由上下两个谐振器A和B组成,谐振器A由两节1/2波长SIRs中心加载一段短路枝节组成,控制第二和第三通带;谐振器B由三节1/2波长SIRs中心加载一段短路枝节组成,控制第一和第四通带,最终得到了尺寸为8.09 mm×14.12 mm(0.10λ_g×0.17λ_g)的四频带通滤波器。实验结果表明,该滤波器的通带可控并且满足低损耗的要求,4个通带的中心频率分别为2.22/3.66/5.63/7.52 GHz,插入损耗分别为0.32/0.41/1.38/0.43 dB,每个通带的回波损耗都优于20 dB,实验结果与理论分析一致。     

基于奇偶模分析法的四模谐振器结构的双通带带通滤波器设计

提出了一款基于四模谐振器的新型双通带带通滤波器.设计的四模谐振器基于微带线结构,由四个开路枝节和一个短路枝节组成.两次采用奇偶模分析法对该四模谐振器结构进行分析.该四模谐振器的每个模式能够实现独立调节,同时每两个模式形成一个通带.采用源与负载耦合的馈电方式,提高滤波器的带外抑制性.该滤波器具有四个传输零点和四个传输极点.测试结果表明,该双模双通带滤波器工作于2.08GHz和6.07GHz,3dB带宽分别为11.06%和7.74%.设计的滤波器具有紧凑的结构,只有0.28λ_g×0.11λ_g大小.     

Compact hexagonal open-loop resonator bandpass filters using capacitive side-coupled stub and spurline technique

Compact quasi-elliptic bandpass filters using hexagonal open-loop resonators are presented. To miniaturise circuit size, a pair of capacitive side-coupled stubs and two pairs of spurlines are placed skilfully into the filter structure. The new filter operating at 1.65 GHz was analysed, simulated and fabricated. Good agreement between simulations and measurements verified the validity of the methodology. Moreover, the circuit size only occupies 21.1 x 14.1 mm2 (?0.21λg x ≅0.14λg).     

基于SISL的介质填充双通带滤波器设计

为实现滤波器的小型化,基于介质集成悬置线(substrate integrated suspended line, SISL)结构提出了一种介质填充双通带滤波器的设计方案. 首先将高介电常数的介质块填充入SISL的空气腔中,提升SISL的等效介电常数,实现电路的小型化,高介电常数介质块可以直接被SISL固定;然后利用T型结连接两组工作在不同频段的滤波器从而使得两个通带相对独立;最后利用仿真软件进行优化,确定介质填充双通带滤波器的尺寸,并进行加工与测试. 仿真与测试结果表明,二者具有较好的一致性,两个通带频率内的回波损耗均优于15 dB,电路的核心尺寸为0.058λ_g×0.139λ_g(λ_g为SISL在第一通带中心频率处的导波波长). 此双通带滤波器具有小尺寸、自封装等优势,且所有层介质基板均采用低成本的FR4板材,降低了制造成本.     

Elliptic-type bandpass filter and bandstop notch filter inspired by metamaterial NRI-TL topology

Compact and highly selective filters can be implemented by loading a transmission line with series printed capacitors and shunt resonant λ/4 stubs resembling the familiar printed negative-refractive-index transmission- line topology. Simulation and experimental results of a microstrip two-stage bandpass filter and a bandstop notch filter are presented. The four-pole bandpass filter exhibits an elliptic-type response with 3% fractional bandwidth. The microstrip bandstop notch filter exhibits a 50 dB deep stopband and a notch /spl varrho/ of 50. Both filters were designed at an operating frequency of 2.0 GHz.     

A UWB Bandpass Filter With Two Transmission Zeros Using a Single Stub With CMRC

A compact bandpass filter is proposed for lower-band ultra-wideband applications. It entails the design concept of a stub-tapped half-wavelength line resonator which provides three transmission poles in the passband and two transmission zeros at the high and low rejection bands. The two stubs are replaced by a single dual-band stub and the parallel coupled-line structures are meandered, leading to a compact size of 0.26lambda_g by 0.32lambda _g     

Geometrical structures and fundamental characteristics of microwavestepped-impedance resonators

λ_g/4-,λ_g/2-, and λ_g-type transmission-line stepped-impedance resonators (SIRs) have been proposed and various practical applications have been reported on the basis of the analysis related to each resonator. This paper standardizes these three types of SIRs and systematically summarizes their fundamental characteristics, such as resonance conditions, resonator length, spurious (higher order) responses, and equivalent circuits. Practical applications which employ features of three types of SIRs are investigated with demonstrations of specific structures. Original design formulas with respect to λ_g-type dual-mode resonators are analytically derived. Advanced SIR's using composite material and multisteps are also introduced and their availability is discussed     

Low Insertion-Loss, Sharp-Rejection and Compact Microstrip Low-Pass Filters

Complementary split ring resonators are used to design compact, low insertion loss (IL), low pass filter with sharp cut-off. A prototype filter implementing area is 0.23 lambda_gtimes0.09lambda _g, lambda_g being the guided wavelength at 3-dB cut-off frequency (f_c) 1.887GHz. Maximum IL is within 0.5dB up to 1.717GHz and 20-dB stopband extends up to 3.4f_c     

Extremely compact dual-band PIFAs for MIMO application

A MIMO structure consisting of two extremely compact planar inverted-F antennas (PIFAs) (λ/60 x (λ/20 x (λ/60) is proposed for GSM 900 MHz and 2.4 GHz wireless local area network applications. The miniaturisation of each antenna is achieved through a spiral-shaped PIFA and a capacitive load, forming a LC resonator. Both antennas have a good impedance bandwidth of 0.88?0.945 and 2.39? 2.48 GHz for 0.9 and 2.4 GHz band, respectively. The two PIFA antennas are polarised orthogonally to each other, and isolation better than 228 dB is achieved in both bands without any structure etched on the ground. The predicted results are compared with the measured data and good agreement is found.     

Tilted- and axial-beam formation by a single-arm rectangular spiralantenna with compact dielectric substrate and conducting plane

A single-arm rectangular spiral antenna is analyzed using the finite-difference time-domain method. The spiral is printed on a finite-size dielectric substrate backed by a finite-size conducting plane. Both the substrate and conducting planes are square with a side length L of less than 0.6λ₀ (λ₀: wavelength in free space). The radiation pattern is dependent on the outermost arm peripheral length C. The spiral whose peripheral length is within 2λ_gg (λ_g: the guided wavelength of the current) radiates a tilted beam of circular polarization. When the peripheral length is decreased to λ_gg, the spiral radiates an axial beam. The axial beam has a wide half-power beam width of approximately 102° (for L≈0.369λ₀) with a gain of approximately 6.7 dB. The axial beam shows a 15% frequency bandwidth for a 3 dB axial ratio criterion. Over this bandwidth, the voltage standing-wave ratio (VSWR) is less than two, as desired. The experimental results for the radiation pattern, gain, axial ratio, and VSWR are also presented     

Expected interference in wireless networks with geometric path loss: a closed-form approximation

In this letter, we derive 2λπP/((α - 2)g^{(α - 2)} as a closed-form approximation of the expected interference around a receiver in wireless networks. We use a geometric path loss model, assume that nodes are randomly distributed, and that only nodes outside a guard zone around the receiver simultaneously transmit. The derived solution depends on the path loss exponent α, node density λ, transmission power per node P, and the radius g of the guard zone. The simplicity of this solution makes it widely applicable in wireless network analysis.     

Harmonics terminated L-band frequency quadrupler using composite right/ left-handed transmission line

A design method for an L-band frequency quadrupler with composite right/left-handed transmission line is proposed. The left-handed transmission line in the proposed frequency quadrupler suppresses the fundamental component (f0), while the composite right/left-handed λ/4 open stub reduces unwanted higher-order harmonics. From the experimental results, unwanted harmonics are suppressed to achieve harmonic distortion of 51 dBc minimum with output phase noise of -94.34 dBc/Hz at 10 kHz offset.     

柔性人工表面等离激元传输线的小型化设计

为了实现高集成度通信系统中高频信号的可靠传输,提出了一种小型化叉指H形人工表面等离激元传输线结构. 采用共面双导体形式,并在金属矩形凹槽处添加叉指结构,实现色散特性调控和尺寸缩减. 同时给出单元结构的等效电路模型,验证了小型化结构的设计原理,分析了力学形变时传输线的性能. 仿真与测试结果表明,与常规的人工表面等离激元相比,叉指H形人工表面等离激元传输线可在保持相同带宽（3～15.25 GHz）的同时,线宽减少79.5%,尺寸仅为2.28λ_g×0.098λ_g（λ_g为中心频率对应的波长）. 在平坦和变形时加工实物的带宽保持在3～12.90 GHz,与仿真结果较吻合. 设计的结构具有高频、小型化和柔性超薄等特点,在超小型高速通信系统中具有潜在的应用前景.     

A compact circularly polarized subdivided microstrip patch antenna

A compact circularly polarized subdivided microstrip patch antenna is proposed. The antenna is composed of the interconnection of four corner patches alternating with four strips and a fifth central patch. It presents the very small size of 0.28λ_g by 0.28λ_g at resonance (5.85 GHz), which represents a surface reduction of 60% compared with a conventional microstrip square patch antenna. The proposed antenna exhibits a gain of 4.3 dBi to 5 dBi and an axial ratio lower than 1.8 dB in the range of its bandwidth, which is of 30 MHz     

Compact and low profile co-located MIMO antenna structure with polarisation diversity and high port isolation

A compact co-located MIMO structure with high port isolation is proposed for 2.4 GHz WLAN application. The antenna structure consists of a proximity-coupled square ring patch antenna, and a probe fed planar inverted F antenna co-located inside. The operating frequency of the two radiators is designed to be at the same frequency, and a high port isolation below -25 dB is achieved with an extremely narrow edge to edge inter-antenna space of 1 mm (0.008λ). The total lateral size of the co-located radiators is only 0.28λ x 0.28λ, i.e. only about 25% of the size of a half-wavelength dual-port patch antenna. The MIMO structure gives high gains (>4.0 dB), low correlation (<0.2), and high diversity gain (about 10 dB).     

Enhanced relaxation oscillation frequency of 1.3 μmstrained-layer multiquantum well lasers

Dependence of relaxation oscillation frequency (f_r) on the bandgap wavelength of InGaAsP barrier layers (λ_g ^b) and number of quantum wells (N_w) were investigated for the first time, for 1.3 μm InGaAsP/InGaAsP compressively strained multiquantum well (MQW) lasers. 1.3 times higher f_r was confirmed for strained-layer MQW lasers with large N _w (N_w⩾7) and wide bandgap barrier layers (λ_g^b=1.05 μm) at the same injection level, compared with unstrained MQW lasers having the same well thicknesses and the same emitting wavelength. This enhancement mainly results from increased differential gain due to strain effects separated from the quantum-size effect     

Resonance frequency of rectangular microstrip antenna on thicksubstrate

A modified cavity model to compute the resonance frequency of a rectangular patch antenna on a thick polytetrafluoroethylene substrate (0.037λ_g 0.229λ_g) with maximum deviation of 2% against experimental results is presented. This accuracy is achieved by accounting for the effect of anisotropy and total losses on the resonance frequency. All other models, including the method of moments (MOM)-based Ensemble, compute resonance frequency with error between 4 and 36%     

一种紧凑型LTCC差分分支线耦合器

为满足微波电路高集成度以及抑制电磁串扰的需求,通过在低温共烧陶瓷(low temperature co-fired ceramic,LTCC)不同层分布具有特定奇模特性阻抗耦合线的方式实现了一种紧凑型差分分支线耦合器.一方面,耦合线在保证差模传输的基础上具有相对集中电场分布的特性,因此可以在LTCC中相互重叠,从而有效减小尺寸;另一方面,耦合线与单条带状线相比可以减少接地层的使用,从而降低损耗.为验证理论预期可行性,设计了一个工作在1.84 GHz频率下,尺寸为0.07λg×0.07λg(λg为中心频率的导波波长)的LTCC差分分支线耦合器.实测结果表明,最小插入损耗为0.6 dB,15 dB回波损耗的相对带宽和隔离带宽分别为18.2％、18.0％,±10°相位差的相对带宽为40.0％.本文设计具有尺寸小、损耗低、带宽增强和易于与差分芯片连接等优点,可以作为一种实用的微波器件.