一种新型宽频带双极化馈源的设计

高效率的宽频带馈源可以大大减少馈源数量,减小天线口径,在天线工程中应用很广。采用正方形振子形式设计的新型宽频带双极化馈源,与传统馈源相比,该馈源具有频带宽、体积小以及波束等化好等优点。首先给出了这种馈源的几何结构和腔体理论分析,并对这种馈源反射腔的几种不同结构形式进行了对比分析,分析结果表明采用圆形反射腔形式是最佳选择。对比仿真分析和理论计算结果,两者非常吻合,验证了理论分析的正确性。     

Demodulation Procedure for Very Wide-Band FM

Since conventional FM demodulators are incapable of accurately demodulating very wide-band frequency-modulated signals, a new approach to the problem is needed. Based upon a theorem by Sandberg, a practical procedure is presented for demodulating not only typical FM signals but also those employing modulation bandwidths and/or frequency deviations on the order of the cartier frequency. The proposed demodulator utilizes an iterative recovery procedure. The first iteration is analogous to demodulation by a conventional zero crossing discriminator and results in severe distortion of the modulation under wide-band conditions. This distortion is reduced by successive iterations. Because, in practice, the iterative process is truncated after a finite number of terms, a procedure for computing the coefficients of these terms for minimum mean-squared error is given. Using computer simulation, the demodulation technique is demonstrated to work effectively for several very wide-band FM signals.     

Ku频段大功率宽频带频率复用馈源

所介绍的适用于双修正型卡塞格伦天线Ku频段大功率宽频带频率复用馈源,其覆盖全Ku频段(即接收10.70-12.75GHz,发射13.75-14.50GHz),功率容量可达2kW,性能完全满足国际卫星组织标准,达到国外同类产品水平。     

一种用于无线局域网的双频带印刷偶极子天线

介绍了一种运用于无线局域网的小型化印刷偶极子天线,它采用对偶极子两个臂开槽结构,使其获得双频带和小型化的特性。采用基于耦合馈电的巴伦馈电方式,使天线具有宽带匹配、结构简单、制作方便、易于集成到无线通信设备中的优点。仿真结果表明,在2.4 GHz和5.8 GHz两个频带的带宽分别为590 MHz(2.13~2.72 GHz约24.33%)和700 MHz(5.24~5.94 GHz约12.52%),而且方向图比较理想。该天线的主要优点是结构简单、体积小、低剖面、成本低、易共形,能够满足WLAN的需要。     

Carrier Synchronizer for Coherent Detection of High-Speed Four-Phase-Shift-Keyed Signals

In a high-speed digital radio relay system with four-phase-shift keying and coherent detection, it is very important to realize an accurate, stable, and wide-band carrier synchronizer. In this paper, the influence of time delay causing trouble for the wide-band synchronizer realization is analyzed. Then the design procedure of this synchronizer is described. Finally, the realizability of such a synchronizer is proved by the experimental results at a 1.7-GHz intermediate frequency and a 200-MHz clock frequency.     

Wide-band de-embedding with a short, an open, and a through line

A wide-band procedure for subtracting the effects of fixtures and device packages or carriers from measured scattering parameters with only a short, an open, and a through line as standards is presented.     

Design of wide-band compact corrugated horns

It is shown that a specially profiled corrugated horn with a ring-loaded input converter section is capable of operating over bandwidth ratios of up to 2.4: 1. The cross polarization across the band is relatively low, and the change in beamwidth and phase-center position with frequency is acceptable for many applications. This "compact" horn is significantly smaller than the conventional wide-band corrugated horn, and is particularly recommended as a feed in a dual-reflector antenna where space is limited.     

Defocusing loss for a log periodic-fed reflector

Log periodic designs are a well established wide-band antenna technology, but one in which the phase center travels along the structure as the frequency varies. When a log periodic antenna is used as a feed for a reflector antenna, the phase center location cannot be maintained at the reflector focus over the frequency range and defocusing results. The purpose of this analysis is to quantify the defocusing loss for a log periodicfed reflector. The analysis presented compares favorably with measured results.     

一种P波段大功率发射用宽带贴片天线研究

提出了一种P波段的宽带开槽贴片天线用于大功率发射天线阵单元。这种天线用蜂窝材料支撑,同轴线直接馈电,能承受最大800W的连续波功率。优化开槽的位置,槽的长度、宽度可以使此天线达到较宽的带宽,并提高天线的效率。为验证设计方法,设计了一个P波段天线,带宽达27%,并测试了其性能。测试结果与仿真结果比较一致,说明了此方法的有效性。     

MoM antenna simulations, with Matlab: RWG basis functions

The Matlab implementation of an MoM antenna simulation code is presented, primarily (but not exclusively) for educational purposes. The PDE toolbox is used to generate the mesh. Evaluating the MoM matrix entries using the Rao-Wilton-Glisson (RWG) basis functions is discussed. The delta-function generator is used to model the feed point. Built-in Matlab functions are used for post-processing. Results for several examples, including thin-strip dipoles, a monopole on a ground plane and a wide-band slot antenna, are presented     

A low-sidelobe partially overlapped constrained feed network fortime-delayed subarrays

Completely overlapped space-fed subarrays have been shown to provide sufficient pattern control to enable (modestly) wide-band arrays using time delays at the input to each subarray and phase shifters at the array face. These configurations are bulky, but have been proposed for space-based use as well as for certain ground-based applications that do not have severe volume constraints. Other applications for space-based and airborne radar require much more compact, constrained array feed networks, but until now there have been few appropriate constrained networks for inserting time delay at the subarray ports without causing high sidelobes. This paper describes one such network that, at the outset, provided far lower sidelobes than the usual contiguous subarrays, but retained closely spaced high lobes near the main beam. This paper presents a synthesis procedure that alters the subarray patterns and reduces nearly all array sidelobes to levels determined by tolerance errors. Several examples are presented that synthesize sidelobes at -40 dB. The resulting network operates over 70% to 80% of the maximum theoretical bandwidth     

An electronically tuned Gunn oscillator circuit

A novel waveguide Gunn oscillator circuit is described that permits wide-band mechanical and electronic (varactor) tuning. A feature of the circuit is that a circuit model can be devised that accurately predicts the oscillator characteristics and that, therefore, can be used to formulate a realistic oscillator design procedure.     

A new excitation technique for wide-band short backfire antennas

A new excitation technique is developed to improve the impedance bandwidth and to lower the manufacturing cost of a short backfire antenna (SBA). The new excitation structure consists of a planar monopole and a microstrip feed line, both of which are printed on the same dielectric substrate. By splitting the printed monopole with a slot, a wide-band performance can be achieved. The new split-monopole-excited SBA achieves an impedance bandwidth of about 15% [voltage standing wave ratio (VSWR <2)] while maintaining good radiation performance. As an example, an SBA configuration with the new excitation topology was designed and measured at the 5 GHz UNII band, and good agreement was observed between the simulation and experiment. The effects of the geometric parameters of the excitation structure on the impedance performance are investigated and the operating mechanism of the split-monopole-excited SBA is discussed. Being a low-cost, high-gain, and wide-band directional antenna, the new SBA can find applications in various wireless systems, such as LMDS, WLAN, and the emerging WiMAX networks.     

Extending the Realizable Bandwidth of Edge-Coupled Stripline Filters

This paper discusses the physical realizability of wide-band parallel-coupled filters in edge-coupled stripline form. Based on the sine-plane approximation, a design procedure that permits the presently realizable bandwidth to be extended from 20 to 45 percent is developed. The new design optimizes the interior impedance level and replaces the end-coupled line sections by quarter-wavelength transformers.     

A cryogenic focal plane array for 85-115 GHz using MMICpreamplifiers

A new focal plane array for 85-115 GHz is described in this paper. This array has 16 pixels, and uses InP monolithic-microwave integrated-circuit preamplifiers with 40-dB gain, followed by a wide-band subharmonic mixer to convert to a 5-20-GHz intermediate-frequency band. A low-loss isolator is used to achieve an excellent input match. Square corrugated feed horns are used for efficient filling of the focal plane. Critical components are operated at a temperature of 20 K. Noise temperature varies from 50 to 130 K, including all pixels across the full band     

Impedance Measurement in Frequency-Halving Networks Using a Two-Frequency Synthetic Loading Technique

A technique is described which removes a major difficulty in the design of wide-band frequency-halving networks: the accurate characterization of the "pumped" input output impedances at the plane of the varactors. The procedure permits the use of realistic input, output power levels with the input at twice the output frequency.     

Reduction of Numerical Dispersion Error in 3-D ADI-MRTD Method With the Coarse Mesh

In order to reduce the numerical dispersion in three-dimensional alternating-direction implicit multiresolution time-domain scheme, a correction procedure is introduced. The numerical dispersion relation and the anisotropic correction parameters are considered. The reduction of the numerical dispersion is investigated for single frequency problem and wide-band simulation with the coarse mesh.      

基于宽带输入阻抗模型的有源集成天线设计

提出了利用微带天线的宽带输入阻抗模型进行有源集成天线的设计方法以预测有源集成天线(AIA)的辐射特性和谐波特性.谐波平衡法被用于得到AIA的谐波特性和阻抗模型的端口电压.然后端口电压作为激励源计算天线特性.实验结果显示该方法可以简单有效进行有源集成天线设计.     

Relation of radar range resolution and signal-to-noise ratio to phased-array bandwidth

Phased-array radar systems using wide-band linear-FM pulses suffer from array dispersion. This causes a loss in signal-to-noise (S/N) ratio and in radar range resolution (a broadening of the compressed-pulse width). Depending on the choice of the receiver matched filter (MF) and weighting filter (WF) one or the other of these effects may be minimized. The effects of dispersion in a square planar array with either a parallel feed or a center-fed series feed are studied. Loss in S/N ratio and in range resolution are determined for typical cases, and general curves are given for arrays with arbitrary size, scan range, and signal bandwidth. It is shown that there is an optimum or maximum-useful signal bandwidth for each array, for which the minimum S/N-loss MF-WF design is the same as the ideal-compressed-pulse-shape MF-WF design. For pulses having greater signal bandwidths, time delay steering should be used in the array.