Design of a wideband compact square waveguide polariser

The computer-optimised design of a compact exponentially profiled E-plane depth corrugated square waveguide polariser is described which achieves 90°±2° differential phase shift between the TE10- and TE01-wave for 11.8?12.5 GHz and 17.1?18.1 GHz. The input VSWR is better than 1.02 and 1.016 for the TE10- and TE01-wave incidences, respectively, between 10.3 and 18.8 GHz. The method of field expansion into suitable eigenmodes used considers the effect of higher-order mode interaction at all step discontinuities.     

Design of a Vivaldi antenna with wideband reduced radar cross section

In this paper, a low radar cross section (RCS) Vivaldi antenna is proposed. The main objective of this work is to achieve a reasonable RCS reduction without affecting the radiation performance of the antenna. With carefully inspecting the surface current distributions at different frequencies and realizing the critical role of the structural mode in reducing RCS, a simple and efficient object shaping method is employed by introducing a number of circular slots in the surface of the radiator to achieve the RCS reduction. These circular slots along the inner circular profile of the Vivaldi antenna can minimize the scattering along the surface of the radiator, which hence leads to a reduction in the monostatic RCS. Comparing the measured results between the reference antenna and the proposed antenna, a significant 11 dB RCS reduction is obtained while maintaining good radiation performance. Simulated and measured results including S-parameters, gain, RCS of the reference antenna and the proposed antenna are presented.     

宽带DRFM雷达干扰机信号处理模块设计

给出了宽带数字射频存储器(DRFM)雷达干扰机信号处理模块组成框图以及信号处理流程,描述了模块实现的关键技术,特别是在FPGA中实现高速信号并行处理的方法.该信号处理模块可以提供1 GHz瞬时处理带宽,存储深度达到2 048 μs,可实现对新体制宽带雷达有效干扰,具有广阔的应用前景.     

一种用于WSN的微小型UWB雷达天线设计

超宽带雷达不受雨、雪、声、风等自然环境的干扰,可用于无线传感器网络并全天候工作;在通信领域,超宽带雷达可避免多径干扰问题,解决无线传感器网络在复杂多径环境中的应用局限问题。故超宽带雷达可以与无线传感器网络形成天然的结合。为满足无线传感器网络低功耗、体积小的要求,设计了一种微小型超宽带雷达天线。该天线为共面波导方式馈电的贴片式微带天线。仿真结果表明,天线具有体积小、带宽广(1.78~2.38 GHz)、全向性好的优点,满足无线传感器网络应用需求,并可避免与已用无线通信频段的干扰,具有广阔的应用前景。     

Eigenwaves of periodic rectangular waveguide with dielectric-filled dips on broad wall

The paper presents a solution of the boundary problem for eigenwaves of periodic structure consisting of rectangular waveguide with dielectric-filled dips on broad wall obtained by Galerkin’s method. The types of waves are analyzed with due regard for the symmetry of structure and field. The results of calculations of basic characteristics of eigenwaves in the baseband are also presented.     

Theoretical design of wideband waveguide circulators

This letter describes the procedure used in designing, by purely theoretical means, wideband waveguide 3-port circulators. An extension of earlier field analysis, together with the usual Polder expressions for ferrite permeability, enables a computer programme to give optimum wideband circulators for any size waveguide with any low-loss ferrite material. Experimental results are given of circulators so designed.     

Coplanar waveguide fed wideband slot antenna

A new design for a coplanar waveguide (CPW) fed slot antenna is presented. The impedance matching and the radiation characteristics of this structure were studied using the method of moment technique. This antenna has an impedance bandwidth (for a VSWR<2) of 49% and a radiation bandwidth of 42% about its 4.8 GHz centre frequency, compared to the 12-20% impedance bandwidth of the standard CPW fed slot antenna. The cross-polarisation in both the principle planes is at least 20 dB below co-polarisation across the entire bandwidth. Simulated and measured results of the antenna are presented. This wideband antenna has significant applications in wireless technologies     

Exploration of a double-tapered disc-loaded circular waveguide for a wideband gyro-TWT

The analysis of a disc-loaded circular waveguide interaction structure of a gyro-traveling-wave-tube (gyro-TWT) considering standing and propagating mode harmonics in the disc-occupied and disc-free regions, respectively, gave the beam-absent dispersion relation of the waveguide. The axial phase propagation constant predicted by the dispersion relation was substituted into the gyro-TWT gain-equation, the latter obtainable from the beam-present dispersion relation of the device. A method of double-tapering the structure dimensions was proposed that consists in tapering the disc-hole radius to distribute the midband frequency of amplification over a wide range of frequencies, and simultaneously tapering the waveguide-wall radius to compensate for gain reduction at band edges due to disc-hole radius tapering. The method has demonstrated wide device bandwidths at relatively large gain values.     

Design and characterization of a 120-GHz millimeter-wave antennafor integrated photonic transmitters

We developed a planar slot antenna on an Si substrate for a photonic >100-GHz millimeter-wave (MMW) transmitter. We designed the antenna by using three-dimensional electromagnetic-field simulators and characterized its performance by using an optoelectronic network analyzer. The transmitter uses a very fast photodiode with high output power. Using these photonic techniques, we succeeded in building this compact photonic transmitter that emits MMWs with a power of >0.2 mW at a frequency of 120 GHz     

基于AD9858宽带雷达信号源的设计及应用

在一些需要高频分辨率、设置转换度的应用场合,直接数字频率合成器(DDS)技术具有其他频率合成方法无法比拟的优势.在介绍DDS的基本原理及其典型器件AD9858的结构和功能的基础上,详细论述了采用单片机+CPLD来控制AD9858实现宽带雷达信号源的设计过程.实际应用证明,该系统设计分辨率高,转换速度快,在窄带时无杂散动态范围SFDR优于75 dBc,宽带无杂散动态范围SFDR优于55 dBC.     

基于AD9858的宽带雷达信号源设计与实现

给出一套宽带雷达信号源的设计方案,它由基带信号源和倍频链组成,产生中心频率为1 GHZ,带宽为800 MHZ的线性调频信号.基带信号源选用了AD公司高性能数字频率合成芯片AD9858,由FPGA实现加载DDS控制字,产生(200±50) MHz的基带信号 .倍频链将基带信号进行上变频和倍频,可输出1GHz±400 MHz的宽带雷达信号.经示波器和频谱仪测试显示,所设计的宽带雷达信号源满足设计要求.     

Design of dielectric-filled cavity filters with ultrawide stopband Characteristics

A methodology is presented for the design of small cavity filters, relying entirely on the use of commercial general-purpose design software. Pertinent filter structures comprise resonated segments of ridge waveguide with evanescent-mode inter-resonator coupling sections, supplemented by impedance-transforming port networks. The ridge and evanescent-mode waveguide segments combine to form a metal-clad dielectric core made of either a single dielectric or a composite material. A parameterized equivalent-circuit model is used to describe each segment based on numerical three-dimensional electromagnetic field analyses. For a bandpass filter, the technique yields low passband insertion loss, an ultrawide upper stopband region, and excellent power handling. The approach provides the option to fabricate structures at low per-unit cost with the help of newly available moldable dielectric materials. The efficacy of the technique is demonstrated with an experimental 1-1.45-GHz bandpass filter.     

一种可编程宽带放大器的设计

以AT89S51单片机和FPGA为控制核心,利用可编程增益放大器THS7001和可变增益放大器AD603,设计一种可编程精密宽带放大器.测试结果表明:该可编程宽带放大器的增益范围为-6～70 dB.通频带为40 Hz-15 MHz.低噪声,并具有自动增益控制功能,动态范围达60 dB.     

一种可编程宽带放大器的设计

以AT89S51单片机和FPGA为控制核心。利用可编程增益放大器THS7001和可变增益放大器AD603,设计一种可编程精密宽带放大器。测试结果表明：该可编程宽带放大器的增益范围为-6～70dB,通频带为40H加15MHz,低噪声,并具有自动增益控制功能,动态范围达60dB。     

一种宽频带自跟踪馈源的设计

针对一种高性能宽频带自跟踪馈源的使用需求, 提出了由8路天线单元合成双圆极化和差波束的新型设计思路.介绍了这种天线实现圆极化和差波束的馈电原理, 应用仿真软件Ansoft HFSS对8单元阵列进行了仿真设计, 给出了仿真方向图, 分析了8路馈电信号幅度和相位误差对设计的影响.结果表明, 该馈源在一定幅度相位误差范围内, 实现了1~12 GHz频带范围内单脉冲跟踪, 且具有良好的性能.     

Compact coplanar waveguide fed ultra wideband antenna with a notch band characteristic

A coplanar waveguide (CPW) fed ultra-wideband (UWB) antenna with a notch band characteristic is presented for 2.4 GHz and UWB applications. The bandwidth is broadened by embedding two inverted L-shaped slots in the CPW ground and the notch band is achieved by etching a rectangle slot in the CPW ground. The notched band can be controlled by adjusting the length of the rectangle slot and the two inverted L-shaped slots. Experimental and numerical results show that the proposed antenna with compact size of 28 × 21 mm², has an impedance bandwidth range from 2.38 GHz to 12.0 GHz for voltage standing-wave ratio (VSWR) less than 2, expect the notch band frequency 5.0–6.0 GHz for HIPERLAN/2, IEEE 802.11a (5.1–5.9 GHz) and C-band (4.4–5 GHz) for satellite and military applications.     

脉冲压缩在超宽带雷达中的应用

超宽带（UWB）雷达是一种新体制的雷达系统,其极大的带宽和分辨率使它具有广泛的应用前景。典型的超宽带雷达系统发射的是冲激脉冲信号,具有很大的带宽,但限制了系统的作用距离。为了解决这一矛盾,本文将脉冲压缩应用于超宽带雷达系统中,并进行了仿真研究,结果证明了脉冲压缩使系统性能得到较大提高。     

Robust transceiver design for wideband MIMO radar utilizing a subarray antenna structure

In this paper, we investigate the possibility to suppress interference in wideband multiple-input multiple-output radar. The idea is to employ tunable filters at the transmitter and the receiver sides, and to derive filter coefficients that result in optimal transmitted signals from a system performance point of view, for a given radar scenario. The system performance is measured in signal-to-interference-and-noise ratio (SINR) at the receiver output, from which the filter properties are derived. The focus is to suppress active jamming interference, and especially deceptive jamming interference. We discuss two ways to derive the transmit and the receive filters. Each procedure utilizes two different power constraints related to the transmit filters. To incorporate imperfections in the given scenario, a robust extension to the design problem is proposed. Two different robust methods are evaluated: one that utilizes a Taylor series expansion of the SINR, and one that exploits a worst-case SINR maximization. Numerical validation illustrates the possibility to suppress interference without actually forming a spatial null in the direction towards interference, and the necessity to design transmit filters that are robust to uncertainties in the given scenario.     

新型多通道宽带接收激励器设计

为满足机载综合前端宽带数据高速射频采样和激励合成的要求,以及解决传统接收激励器平台方案中接收激励与信号处理未分离和传输数据带宽不足两大问题,提出了新型多通道宽带接收激励器设计方案。该方案不仅实现了多通道500 Msample/s高速模数、数模转换,还通过对接收激励通道及高速数据接口逻辑巧妙设计实现了在接收端完美复原传输端数据流信号,实现了FPGA的4x高速吉比特传输接口与后端信号处理FPGA之间最高可达10 Gb/s的高速点对点数据通信,实现了真正意义上的多通道宽带接收激励功能,具有推广意义。     

一种可展宽频带的微带贴片天线

提出了一种可展宽频带的微带贴片天线。通过对普通矩形微带贴片天线进行切角而展宽频带。由贴片天线的谐振频率和该贴片上的电流分布出发,研究了产生宽带特性的机理。采用基于有限元算法的高频电磁场仿真软件ANSOFTHFSS对该天线的电特性进行计算,结果表明：该天线的阻抗带宽（S11〈-10dB）达到16％（370MHz）。证明了该方法的有效性。