The characteristics and energy coupler of the single row comb circuit for MMW BWO's

In comparision with other slow wave systems, the comb type circuit exists some superior features, such as more large size, easy manufacture and good heat dissipation, so it is suitably used in millimeter wave BWO's. The dispersion equation of the single row comb circuit has been solved. The dispension and impedance as a function of the dimensions of the comb circuit are disscused. The energy coupler is developed for the single row comb circuit. The measurment shows that a broadband match with a VSWR of better than 2.0 is obtained over frequency range from 26.5 to 40 GHz for the coupler.     

A novel noncontacting waveguide backshort for submillimeter wave frequencies

A novel noncontacting waveguide backshort has been developed for millimeter wave and submillimeter wave frequencies. It employs a metallic bar with rectangular or circular holes. The size and spacing of the holes are adjusted to provide a periodic variation of the guide impedance on the correct length scale to give a large reflection of rf power. This design is mechanically rugged and can be readily fabricated for high submillimeter wave frequencies where conventional backshorts are difficult or impossible to fabricate. Model experiments have been performed at 4 GHz – 6 GHz to empirically optimize the design parameters. Values of reflected power greater than 95% over a 30% bandwidth have been achieved. A specific design is presented which has also been successfully scaled to WR-10 band (75 GHz – 110 GHz). A theoretical analysis is compared to the experiments and found to agree well with the measured data.     

具有双陷波特性的超宽带天线设计

设计了一款基于共面波导馈电的小型化具有双陷波特性的超宽带天线,该天线的带宽在3～14 GHz内,电压驻波比(VSWR)小于2。在辐射贴片上通过开L型和半圆环缝隙实现了在3.3～3.7 GHz和5.150～5.825 GHz的双频段的陷波特性,抑制了802.16无线城域网和无线局域网对超宽带系统的干扰,在整个工作频段具有稳定的增益和良好的全向性。通过对天线模型进行加工制作并测量,测试结果表明:天线的带宽是3～14 GHz,在3.3～3.7 GHz和5.15～5.825 GHz频段内VSWR大于4,实现了天线的双陷波特性。该天线尺寸小、结构紧凑的特点,适合现代的无线通信系统。     

A Mode Converter with Multi-waveguide Output from the TE01 Circular Waveguide Mode to the TE10 Rectangular Mode for Millimeter Wave Gyro-device Applications

A mode converter with multi-waveguide output for millimeter wave gyro-device applications is proposed in this article, which is used to convert the TE₀₁ circular waveguide mode into the TE₁₀ rectangular waveguide mode. Computer simulations with Ansoft HFSS code show that the energy transmission coefficient of larger than 95.96% may be reached in the frequency range from 34.094 GHz to 35.8 GHz (a bandwidth of 1.706 GHz) at a VSWR of lower than 1.5 for the input operating mode.     

同轴高功率超宽带功分器研究

 运用同轴结构,研制出高功率超宽带功分器,采取先阻抗变换,再功分的形式,以简化机械加工难度。运用高频仿真软件进行仿真分析,研制出一分为二和一分为四的功分器,再组合成为一分为八的功分器,高压实验表明该功分器能耐高压,驻波测试表明阻抗匹配较好,从测量的传输参数可以看出输出各端口幅度一致性较好。证明了该高功率超宽带功分器可以用作实际的高功率天线阵列。     

过模矩形波导中硅芯片与基模亚毫米波的作用

模拟研究了过模矩形波导WR10中n型硅探测芯片对TE10模亚毫米波的响应。针对过模波导WR10中内置n型硅芯片的亚毫米波探测结构,推导了基模工作时的灵敏度表达式。采用三维电磁场时域有限差分方法,模拟计算了过模波导中300～400GHz频带的TE10模亚毫米波与硅芯片的相互作用,分析了探测结构中电压驻波比和芯片内平均电场随硅芯片参数变化的规律。结果表明,在相同的芯片参数下,过模探测结构并不影响电压驻波比和芯片内平均电场的大小,但两者随频率变化的波动程度增大。在300～400GHz工作频带内,优化得到了性能较优的过模探测结构,其电压驻波比不大于2.75(335～380GHz频带内不大于1.8),线性工作区的相对灵敏度约为0.127kW-1,频率响应的波动范围在±20.5%内,最大承受功率约为0.53kW,响应时间为100ps量级,满足亚毫米波大功率脉冲的直接探测需求。     

140GHz大功率交错双栅行波管的设计和模拟研究

采用交错双栅结构,结合带状电子注,研究了一种工作在140 GHz频段的大功率行波管. 本振模数值计算表明该结构具有良好的色散特性和耦合阻抗.针对所采用的慢波结构, 提出了慢波过渡结构、输入输出耦合器和集中衰减器,保证了行波管的良好工作. 利用三维大信号模拟计算的方法得到的结果显示,当电子注直流功率为5.115 kW,输入信号功率为0.1 W时, 所研究的行波管能在132-152 GHz范围内提供大于300 W的峰值功率,其中在138 GHz时得到最大功率546 W, 对应增益为37.37 dB.当在0.027-0.46 W内调节输入信号功率,可以保持该行波管在128-152 GHz 频带内得到大于440 W的峰值功率,对应的电子效率大于8.6%. 结果显示该行波管将在大功率短毫米波领域具有重要意义和潜在应用价值.     

同轴转弯波导的设计与实验研究

提出了一种同轴转弯波导。介绍了该同轴转弯波导的基本原理,设计并数值模拟了中心频率为4.0 GHz的同轴转弯波导,并对此同轴转弯波导进行了实验研究。实验结果表明:同轴转弯波导在中心频率4.0 GHz下,传输损耗约为0.17 dB,驻波系数为1.2;在3.8~4.2 GHz的频率范围内传输损耗小于0.2 dB,驻波系数小于1.25。同轴转弯波导内部无介质支撑,且体积小,结构简单,易于实现,适用于高功率微波馈线系统中的同轴波导的转弯和连接。     

Impedance Characteristics of Two Coplanar RLTs in Millimeter Wave VCO Waveguide Cavities

Impedance characteristics of two coplanar radial line transformers (RLTs) placed in millimeter wave voltage control oscillators (VCOs) waveguide cavities have been studied in this paper. Mode matching methods are employed to calculate self impedance of the RLT mounted on active device and mutual impedance of the two coplanar RLTs. Some general rules concerning impedance characteristics of two coplanar RLTs configuration influenced by the parameters of the structure have been deduced. In addition, an equivalent network is presented based upon the impedance matrix of the coplanar RLTs; the load impedance looking outward from the active device has been derived in virtue of the equivalent network and the impedance of varactor diode. The equivalent network which describes the relationships between the load impedance and the impedance of varactor diode is helpful for developing millimeter wave varactor-tuned VCO of this structure.     

亚毫米波大功率脉冲探测器的初步研制

初步研制了一种用于300~400GHz频段的亚毫米波大功率脉冲探测器。基于强电场下的热电子效应,将n型硅探测芯片置入波导WR10的宽边,构成了探测器的过模探测模块。采用光刻和电镀工艺完成了探测芯片的加工,实现了很好的欧姆接触和尺寸精度。对集成的探测器样机进行了亚毫米波大功率脉冲测试和电压驻波比测量。结果表明:探测器样机的响应时间快达ps量级,相对灵敏度约为0.46kW-1,电压驻波比小于2.4,最大承受功率不小于数十W,与模拟结果符合得较好,满足亚毫米波大功率脉冲的直接探测需求。     

具有三陷波特性的超宽带天线设计

设计了一款基于共面波导(CPW)馈电小型化具有三陷波特性的超宽带天线。该天线采用矩形贴片组合作为辐射单元,通过在辐射贴片上开倒U型、圆弧形和S形缝隙来实现陷波功能,有效地抑制了WiMAX（3.3~3.7 GHz）,WLAN（5.150~5.825 GHz）和X波段卫星通信系统下行频率段（7.25~7.75 GHz）对超宽带系统的干扰。结果显示:该天线在3.1~12.0 GHz内电压驻波比小于2,整个工作频段内具有稳定的增益和良好的辐射方向特性。     

A Future Millimeter/Sub–Millimeter Radiometer for Satellite Observation of Ice Clouds

The instrument concept of a future spaceborne millimeter/sub-millimeter radiometer is proposed in this paper for the remote sensing of ice clouds from satellite. The proposed radiometer is expected to operate at a series of frequencies within the millimeter and sub-millimeter wave range from 150 to about 900 GHz. Five frequencies are selected in the atmospheric windows, i.e., 150, 220, 463, 683, 874 GHz, and at each frequency there are two orthogonally polarized channels. Three water vapor channels located close to 183.31 GHz are also included in this instrument, since they can provide water vapor information, which is needed for ice cloud parameter retrieval. To simplify system design and test, a modular design philosophy is followed in the receiver frontend design and two antennas are used separately for the millimeter and sub-millimeter channels. Overall, the instrument requirements can be met with today's technology, except for the channels at the highest frequencies, where the radiometric sensitivity can be larger than the required 1.0 K for the 10 km spatial resolution (2.5 ms integration time). However, this situation can be improved by averaging neighboring pixels in data processing if certain compromise in the spatial resolution can be made at these frequencies.     

异面带状线馈电的宽带双极化蝶形天线

针对通信与雷达系统对双极化与宽带天线的要求,提出了一种基于带状线馈电的双极化蝶形天线。通过两对互相正交的蝶形阵子实现了天线的双极化,并采用一种新型的微带线转异面带状线的巴伦给两对正交蝶形阵子平衡馈电。异面带状线为平衡传输线,满足了蝶形阵子对于平衡馈电的要求。在馈电点处由同轴线对微带线馈电,经渐变微带线转化为异面带状线,最后由两组异面带状线给两对正交蝶形阵子馈电。测得该天线实现了69.23%的阻抗带宽,在6.8~14GHz频带内电压驻波比(VSWR)小于2。为使天线单向辐射且改善天线增益,将天线放置于反射吸收腔内。测得天线在6.8~18GHz的频宽内VSWR基本小于3,天线增益在8~12GHz频带内大于0.11dB,天线前后瓣比大于15dB。因此,所提出的双极化蝶形天线可用于宽带通信系统中。     

Metal mesh couplers using evanescent waves at millimeter and submillimeter wavelengths

In this paper we introduce a metal mesh evanescent wave coupler that makes use of evanescent wave coupling between a metal mesh and a dielectric plate, as a quasi-optical component for millimeter and submillimeter wavelengths. The transmission properties of this type of couplers have been investigated experimentally and theoretically for both capacitive and inductive metal meshes in the frequency range from 40 GHz to 60 GHz. The transmittance of a capacitive metal mesh evanescent wave coupler can be adjusted more than 70% by changing the spacing between the capacitive mesh and the silicon plate less than 0.15 mm at around 57 GHz.     

折叠矩形槽波导行波管输入输出过渡波导

为了将槽波导端与标准矩形波导相连接,设计了一种适用于折叠槽波导结构行波管的输入输出过渡波导, 可将其视为槽宽渐变的双槽加载矩形波导。利用电磁仿真软件CST微波工作室对该结构进行仿真计算,讨论了各个结构参数对其性能的影响。对比了直线渐变、抛物线渐变和指数渐变3种槽宽渐变规律在W波段对其传输特性及损耗特性的影响。研究结果表明:指数渐变结构的驻波系数小于1.15的带宽比其他两种结构都要宽,且在90~99 GHz、驻波系数小于1.25时,该结构的整体长度也远小于另外两种结构,能够实现良好的过渡效果; 而直线渐变结构的损耗在90~97 GHz为最低。     

毫米波生物效应聚焦装置的设计

 采用喇叭天线与透镜相结合的准光技术方案,设计了毫米波生物效应聚焦装置,其频率达到95 GHz,辐射功率达GW级。毫米波辐射源传输到波纹喇叭天线产生的波束经透镜变换得到所需的高斯波束,实现波束能量的汇聚。在毫米波辐射源功率为W级的条件下,该装置的焦斑功率密度达到0.01～2 W·cm^-2,焦斑面积为0.8～30 cm²。该实验装置在毫米波生物效应实验中已得到成功应用。     

A Millimeter Wave Phase Locked and Frequency Multiplying Source

A millimeter wave phase locked and frequency multiplying source is proposed in this paper. The design includes an X-band phase locked loop (PLL) frequency synthesizer as the base frequency source, and a monolithic millimeter wave frequency tripler, which is developed by using OMMIC 0.18μm pHEMT process. The PLL and the tripler are integrated in a single circuit board to make a low-cost and compact frequency source with the size of 6cm × 5cm. Measurement shows an output power of more than 4.8dBm at the frequency range from 35 to 36.7GHz. A phase noise of about -92dBc/Hz at 100kHz offset is achieved.     

螺旋线行波管慢波结构设计及注波互作用模拟

通过模拟计算,分析螺旋线内径和螺距变化对色散和耦合阻抗的影响,优化慢波结构,初步设计了Ku波段螺旋线行波管慢波结构。模拟行波管输入输出结构,得到输入端反射系数小于-19 dB,电压驻波比小于1.24。电子聚焦系统采用周期永磁聚焦,磁场周期为8.5 mm,计算得到磁场峰值为0.17 T。为提高注波互作用效率,采用具有动态速度渐变特性的慢波结构,使得电子注与高频场有足够的互作用时间,从而保证电子不断地将能量交给高频场。运用三维PIC粒子模拟软件分析行波管的注波互作用,得到在12.5~16 GHz频率范围内输出功率大于88.7 W,电子效率大于14.8%,增益大于34.6 dB。     

Dual and broadband power dividers at microwave frequencies based on composite right/left handed (CRLH) lattice networks

This paper proposes a dual-band power divider operating at GHz frequencies and implemented by means of impedance transformers (also called inverters) based on lattice networks and transmission line sections. The dual-band functionality of the proposed device is achieved thanks to the composite right/left handed (CRLH) behavior of the impedance transformers, able to provide −90° and +90° phase shift at the first and second design frequencies, respectively, of the divider. By using such combination of transmission line sections and lattice networks, the characteristic impedance of the impedance transformers is roughly constant over wide bandwidths, with the results of broad operating bands. To demonstrate the possibilities of the approach, a prototype device is designed, fabricated and characterized.     

Calculation of Mutual Coupling between Two RLTs in Millimeter Wave VCO Waveguide Cavities with Mode Matching Methods

In the design of millimeter wave voltage control oscillators (VCOs), mutual coupling effect is of great importance for it influences the tuning and power characteristics of VCOs significantly. In this paper, mutual coupling between two in-line radial line transformers (RLTs) in rectangular waveguide cavities of millimeter wave VCOs has been evaluated with mode matching methods. Mutual coupling characteristics varying with various parameters of resonate cavity such as the distance between two diodes, the position of sliding short, the radii of bias pins, the radii of RLTs, and the height of diodes are presented. Some useful conclusions concerning two RLTs configuration have been derived, which is helpful to design millimeter wave VCO of this structure.