TE01-TEM00 Quasi-Optical Mode Converter

A new quasi-optical TE₀₁-TEM₀₀ mode converter is presented. It consists of four mirrors sequentially correcting diffraction divergence of TE₀₁ mode, its polarization, then amplitude and phase patterns. Results of the measurement performed at millimeter waves agree well with the design parameters: total conversion efficiency exceeds 90% in the frequency band of 20%.     

太赫兹宽带Denisov型准光模式变换器的设计分析

研究并设计了一种具有宽频带工作能力的太赫兹准光模式变换器。该准光模式变换器采用具有高效率特性的Denisov 辐射器,工作在TE_6,2模式,用于实现回旋管内的模式变换。由于Denisov 辐射器的参数是影响准光模式变换器宽带性能的主要因素,因此通过对辐射器参数的优化设计,达到增大模式变换器带宽的效果。使用自主开发的准光学模拟程序进行仿真,模式变换器中心频率为94 GHz,带宽达2 GHz。     

多通道一体化变频器总体设计与研究

针对多通道变频器的特点,提出了详细的设计流程。按照设计流程,分别对该设备的结构总体设计和详细的模块设计进行了论述。设计的多通道变频器具有以下特点:结构上支持盲拔插,共用时钟模块和电源模块,也可以实现任意频段的上下变频组合,因此微波变频设备趋向于小型化、集成化、通用化的方向发展。     

基于天线测试系统的简易扩频设计及应用

基于通用天线近远场测试系统,给出了系统扩频设计和工程应用的思路,并分别对扩频系统的本振相参、上下变频的一致性进行了论述。实现了Ka频段以下的平面近场、远场天线测量系统的扩频与应用,并给出了8单元EHF频段阵列天线在不同测试系统下的天线测试方向图。测试结果表明,经扩频的测试系统方向图测量数据与毫米波天线测试系统直接测量的结果吻合,说明扩频系统能够满足毫米波天线方向图的测试需求,并具有较高的测试精度,且设计成本较低。同时还具有一定的通用型,对天线的毫米波扩展测试具有较好的工程应用价值。     

宽带Ka频段下变频器的设计与实现

介绍了一种宽带Ka频段下变频器的设计与实现。变频器链路采用低本振的二次变频方式,无频谱倒置,通过合理的频率配置和电平分配,减小了混频非线性导致的组合频率干扰,降低了输出杂散。变频器本振源应用双环频率合成技术实现了宽带、低噪声输出,设计结果得到了测试验证。变频器结构设计采用了模块化技术,便于调试、故障定位和维修,可广泛适用于Ka频段卫星通信地面站。     

基于遗传算法的四频功分器设计

提出了一种考虑台阶效应的四频功率分配器的新分析设计方法,它以遗传算法为基础。根据理想传输线模型,四频等分Wilkinson功分器主要由4节阻抗变换器与4个隔离电阻构成,文中先采用遗传算法并结合偶模分析方法进行对阻抗变换器参数的优化设计,然后再在ADS软件完成隔离电阻的设置。为验证该方法的正确性,设计了0~5 GHz的四频Wilkinson功分器,实验结果表明,在所需的多个频点均拥有良好匹配与隔离度。     

移相全桥ZVS变换器的优化及参数设计

针对移相全桥ZVS变换器实际电路参数选取困难问题,简要介绍了其工作原理并以工程计算方法详细设计了谐振电感、隔直电容、高频变压器、滤波电感电容等主电路关键元件参数。以此参数研制了一台48V/1KW,50kHz的样机,经测试表明该变换器能在30%及以上负载范围内实现零电压开关,纹波小于2%,30%负载时效率达到74%,60%及以上负载时效率达到85%以上,证明了参数设计的合理性。     

Characteristics of the mode converter of Gyrotron FU CW GII radiating Gaussian beams in both the fundamental and second harmonic frequency bands

Gyrotron FU CW GII, the second gyrotron of the Gyrotron FU CW G-series with an internal quasi-optical mode converter, was recently developed at the Research Center for Development of Far-Infrared Region, University of Fukui (FIR FU) [Y. Tatematsu et al., J. Infrared, Millimeter, Terahertz Waves 35, 169 (2014)]. The design oscillation mode of this gyrotron is TE_8,3 with a corresponding frequency of 393.4 GHz in the second harmonic cyclotron resonance. We observed oscillations of different modes including fundamental harmonic modes in the 200-GHz band upon varying the strength of the magnetic field in the cavity. Radiation patterns corresponding to these modes emitted from the window were Gaussian although the internal mode converter was designed for the TE_8,3 mode. The directions of the radiated Gaussian beams were found to depend on the oscillation modes with a relation similar to that obtained for another gyrotron that was also equipped with a mode converter. This relation is explained based on geometrical optics. Moreover, numerical calculation with the electromagnetic wave code developed in FIR FU confirmed the same relation. The observed features of the Gyrotron FU CW GII show that it can serve as a unique power source with two frequency bands at 200 and 400 GHz. This result provides a way of developing multiple-frequency gyrotrons.     

L波段直接调制解调变频器与L波段变频器

本文介绍了L波段变频器和L波段直接调制解调变频器的工作原理，并就这两种变频方式进行了比较。     

Design of the H<Subscript>10</Subscript><Superscript>□</Superscript> to H<Subscript>01</Subscript><Superscript>°</Superscript> Sector-Type Mode Converter at Ka-Band

A design procedure for the H₁₀^□ to H₀₁^° sector-type mode converter at Ka-band is described in detail. As an example, an H₁₀^□ to H₀₁^° sector-type mode converter with an input rectangular port size as 7.112×3.556 mm² and another output circular port diameter as 17.2 mm is designed and measured for insertion losses and wanted mode pattern. The mode converting efficiency from H₁₀^□ mode to H₀₁^° mode is about 91.2%. The insertion losses of the converter are lower than 0.1525 dB with 2GHz band.     

Analysis of Image Recovery Down Converter Made by Planar Circuit Mounted in a Waveguide

This paper presents an analysis of a superhigh frequency (SHF) down converter using a Schottky-barrier mixer diode and a planar circuit mounted in a waveguide. The analysis assumes that the mixer diode consists of a nonlinear conductance g, a junction capacitance C/sub j/, an ohmic spreading resistance R/sub s/, and several parasitic susceptances. The frequency performance of the impedance of external circuits at the signal, image, and intermediate frequency bands is considered. This analysis also includes consideration of the mismatching effect between the converter and the IF amplifier, and the optimum design procedure for the down converter. Using this theoretical method, a SHF down converter was designed and constructed. Its application is low noise receivers for satellite broadcasting. The design used the optimum image condition (the image impedance takes a low value, i.e., nearly a short). The RF band is 11.7 - 12.2 GHz, the IF band is 0.96 - 1.46 GHz, and the total noise figure is 3.3 - 3.7 dB. The noise figure is in good agreement with the (3.2 - 3.6 dB) obtained from this analysis.     

一种双分裂环结构的线-圆和线-交叉极化转换器

文中提出了一种高效、多功能的超表面极化转换器,该转换器由双分裂环谐振器周期阵列构成并置于F4B-2介电基板上。通过双分裂环谐振器的耦合效应可以有效拓展工作带宽。采用有限积分法对其极化特性进行分析。仿真结果表明：在5.5～8.55 GHz的频带(相对带宽为43.4%),实现了线极化到圆极化的转换,其能量转换效率优于99.5%;在10.31～15.31 GHz的频带(相对带宽为39%),实现了线极化到其交叉极化的转换,其极化转换比大于0.99。实验上,制备了样品并测试了其极化转换特性,实验结果与仿真结果基本吻合,验证了该转换器设计的合理性和有效性。所提出的超表面具有高效率、大工作带宽、多功能的特点,可应用于无线通信和极化操控设备。     

High Efficiency Mode Converter for Low-Frequency Gyrotron

A high efficiency quasi-optical (QO) mode converter for high-power, low-frequency gyrotron have been designed and tested. For low-frequency gyrotrons, the scales of the mode converter are comparatively small on the wavelength scale, thus causing significant diffraction losses. Over-1 MW power gyrotron with TE_8,3 cavity at 28 GHz have been developed, which has a high efficiency mode converter designed by the use of numerical methods for launcher optimization. This calculation is sufficiently optimized to maximize the fractional Gaussian content of the far field. The total transmission efficiency from the mode converter to output window is 94.7%. For the experimental result of first tube, the output power of more than 1 MW has been obtained with about 40% efficiency and output burn pattern agrees fairly with the calculated profiles, which imply the design appropriateness. Besides, the frequency dependence for diffraction loss is discussed, and these results give the guiding design principle of the mode converter for high-power, low-frequency and long-pulse gyrotrons.     

一种数字化接收机的实现方案研究

讲述了在宽带中频数字化接收机中的带通采样及抽取技术。通过具体的例子，分析了带通采样定理，多级抽取的应用及HSP50214B数字下变频器各级抽取因子和滤波器设计思路，用软件无线电的思想构造了一个数字化接收机的试验平台。     

A 200-MHz IF 11-bit fourth-order bandpass ΔΣ ADC inSiGe

This paper demonstrates the design of an integrated fourth-order bandpass sigma-delta converter, which is capable of digitizing a 200-kHz band at 200 MHz with 11-bit accuracy. The converter has been successfully fabricated in a 50-GHz SiGe bipolar technology, and the modulator consumes 21 mA at 3 V. The converter is aimed at the digitization of wireless signals at a high first intermediate frequency with a wide dynamic range     

High-power Mode Converter of Overmoded Bent Circular Waveguide

Based on the mode coupling theory, a TE₀₁—TM₁₁ mode converter was designed and optimal results were obtained. In this paper, bandwidth of mode converter with axis exponential structure is the largest, and mode converter with axis sinusoidal structure is the most compact in the case of the center frequency is 28GHz and the waveguide radius is 16mm. If the bending angle between input port and output port of mode converter was demanded for 90°, mode converter with axis parabola structure had the characteristics of compact structure, higher mode purity and larger relative bandwidth. Meanwhile, we found that the converter could be also used as TE₁₁ mode transition with transmission efficiency above 99%. But due to bending angle of this structure was restricted, its center frequency and waveguide radius had the obvious corresponding relation.     

Current-Pumped Abrupt-Junction Varactor Power-Frequency Converters

This paper presents equations and design curves for a noninverting frequency converter which will enable the engineer to design efficient, high-level parametric devices using abrupt-junction varactors. In addition, the excellent intermodulation characteristic and extremely wide dynamic range (in excess of 140 dB) of the parametric frequency converters enables their use immediately as low-frequency downconverters or microwave upconverters without any deterioration of other parameters, such as noise figure, in system performance. It has been shown that these abrupt-junction diode devices possess the largest known dynamic range, in addition to being relatively spuria free with respect to intermodulation products produced by the diode nonlinearity, intermodulation distortion being generated in the device due only to gain saturation. The design curves also indicate the maximum conversion efficiency possible with a given abrupt-junction diode. An inflection point for 50 per cent converison efficiency occurs for all diodes. Any additional improvement in pump-to-sideband efficiency greater than 50 per cent gained by adjusting the diode and circuit performance, requires relatively large increases in the diode cutoff frequency and reduction in overall circuit losses. Other design curves include impedance variation with drive powers and the overall limiting output power capability for a given diode. A design example is presented to demonstrate the usefulness of the derived results and design curves. The experimental results obtained with this design have demonstrated a microwave, C band, tunable converter with almost 50 per cent conversion efficiency.     

一种针对LLC串联谐振变换器的精确设计方法

本文针对LLC串联谐振变换器提出了一种新颖的基于时域分析的精确分析方法，给出了设计。的准则和流程。LLC串联谐振变换器具有拓扑结构简单，高效率和易高频化的特点，目前得到了广泛的应用。为了优化设计并澄清其设计准则，充分理解该拓扑的直流增益特性以及各参数对效率的影响显得尤为重要。而基于基波近似的传统频域分析方法难于给出准确的结果。本文依照所提出的精确分析设计方法，搭建并测试了一个MHz的LLC串联谐振变换器，其效率达96％。试验结果证实了所提出的时域分析方法和设计准则的有效性。     

Design of a Quasi-Optical Mode Converter for a Frequency Step-Tunable Gyrotron

The quasi-optical mode converter for a frequency step-tunable gyrotron which consists of a dimpled-wall antenna (Denisov-type launcher) and a beam-forming mirror system has been optimized for 9 modes from TE_17,6 at 105 GHz to TE_23,8 at 143 GHz. The first mirror is a large quasi-elliptical focusing one; the second and third are phase-correcting mirrors with a non-quadratic shape of the surface. The results of calculations show that for these modes the Denisov-type launcher has a well-focused beam with low diffraction losses, and the radiation pattern presents an almost identical field shape for all modes considered. A multi-mode optimization of the phase-correcting mirrors with two different methods has been tested. The simulations show that the phase-correcting mirrors can be used for broadband operation in the frequency range from 105 GHz up to 143 GHz in the various design modes. This quasi-optical mode converter can achieve efficiencies of 94%-98% for converting the rotating high-order cylindrical cavity modes into the usable fundamental Gaussian mode.     

Design-oriented analysis of boost zero-voltage-switching resonantDC/DC converter

Analysis and design procedures are presented for a high-efficiency, high-frequency, boost zero-voltage-switching resonant DC/DC power converter. Equations describing converter operation are derived. The basic performance parameters of the circuit are analyzed as functions of the normalized load resistance and switching frequency. These equations are then used to determine conditions for lossless converter operation and design equations that yield the required component values