S波段高功率径向线输出窗的设计

为进一步改进和优化高功率径向线阵列天线的拓扑结构,提高功率容量水平,并满足馈源的真空密封需求,提出并设计了一种适用于高功率径向线阵列天线的微波输出窗。该高功率径向线输出窗采用圆环形陶瓷,材料介电常数为9.4,窗片厚度为3 mm,内径为36 mm,可实现径向线阵列天线馈电系统的输入同轴波导与输出同轴波导间的真空密封。设计结果表明:在中心频率为2.856 GHz下,该径向线输出窗驻波比为1.03,插入损耗为0.17 dB,设计功率容量约150 MW。     

Study of Low Sidelobe Time Modulated Linear Antenna Arrays at Millimeter-Waves

In this paper, the time modulation technique for the design of low sidelobe antenna arrays is extended to millimeter-wave frequency band. Millimeter-wave rectangular waveguide is selected as the element radiators of linear antenna arrays, and the element radiation patterns are taken into account in the analysis and design of low sidelobe time modulated linear arrays. Two types of time modulation, namely, the time modulated variable aperture sizes (VAS) and unidirectional phase center motion (UPCM), are implemented in the design of low sidelobe millimeter waveguide linear arrays. It is observed that both the co-polarized and the cross-polarized components will experience the time modulation effect simultaneously. Many factors that affect the array performance are discussed.     

L波段高功率线极化径向线阵列天线理论分析与数值模拟

 探索了L波段的高功率线极化径向线阵列天线。基于三角形栅格形式实现了径向线圆形平面阵列天线,分析并给出了径向线并联馈电网络,并以同轴馈电的水平单圆环线极化天线为基础,利用径向线并联馈电网络设计出了间距小于一个波长下L波段高功率线极化径向线阵列天线。研究结果表明：这种结构实现径向线阵列天线的线极化辐射是可行的,该天线在中心频率1.57 GHz下,增益为19.97 dBi,轴比为-52.06 dB,反射系数为0.105 2;在1.37～1.77 GHz的频率范围内增益大于18.64 dBi,轴向轴比值小于-46.45 dB。     

高功率谐振式波导缝隙阵宽角扫描技术

在传统高功率缝隙波导阵列中,缝隙间的相互耦合严重影响了阵列的宽角扫描能力。以实现阵列宽角波束扫描为目标,通过分析阵列扫描特性,从提高缝隙阵元间隔离度的角度出发,提出在阵列中引入隔离栅结构,降低了阵元间耦合对阵列大角度扫描时的影响。在此基础上,设计了基于波导窄边斜缝的谐振式阵列天线,采用电磁仿真软件优化阵列。数值模拟结果表明,未采取措施前阵列的最大扫描范围为±34°,引入隔离栅后扫描范围可扩大至±45°,波导端口S₁₁≤?10 dB,增益仅下降了2.3 dB,单根缝隙波导功率容量达330 MW,有应用于高功率微波领域的潜质。     

64单元矩形径向线阵列天线馈电网络的设计

 提出并设计了一种新型耦合探针,研究表明,该探针能有效地扩大耦合调节范围,并基于此探针,研究了中心频率为2.1 GHz的64单元矩形径向线天线阵馈电网络,并进行了优化设计。模拟结果表明:该口径为744 mm×744 mm的馈电网络在中心频率处能达到64路近似等幅馈电,中心频率处的反射系数小于0.1,在2.05～2.15 GHz的频带范围内,反射系数小于0.2。     

Formation of Nulls in Vector Beam Patterns of Monopulse Arrays of Rectangular Waveguides by Correcting Currents in Some Array Elements

In this paper, we consider a method for null synthesis in the vector sum and difference beam patterns of a monopulse array of rectangular waveguides. The synthesis of nulls is reached due to variation of complex currents in some elements. The proposed method eliminates shifts of the primary maximum and the nulls of the sum and difference beam patterns, respectively, of a monopulse array. Numerical studies confirming the efficiency of the proposed method are described.     

高功率线极化径向线阵列天线优化及实验研究

为了提高高功率线极化径向线阵列天线性能(口径效率及反射特性等),实现更优的径向线线极化阵列天线辐射,通过提高单元天线性能、调整阵列布局、改进馈电径向线和探针这3种途径对其进行了优化,并对其进行了理论分析、数值仿真和实验研究。实验结果表明:在中心频率1.57 GHz下,驻波比为1.19,增益为17.65 dBi,轴比为-39.2 dB;在1.47~1.77 GHz的频率范围内驻波比都小于1.4。     

基于极化转换超表面的宽带低雷达散射截面缝隙天线阵

提出了一种利用极化转换超表面(PCM)来缩减雷达散射截面(RCS)并保持缝隙天线阵列辐射特性的新型天线,在不影响天线性能的情况下实现了天线的宽带RCS缩减。该PCM由45°倾斜的开槽矩形贴片周期排布构成,它被放置在缝隙阵列天线的上表面,起到RCS缩减的功能。分析了RCS缩减的特点和原理,仿真和实验结果表明,带有PCM的缝隙天线阵在x极化和y极化波冲击下,单站RCS缩减带宽为8.0～21.8 GHz。同时天线的辐射特性在阻抗带宽、增益和辐射模式等方面都能保持良好性能。     

三角形栅格矩形径向线螺旋阵列天线的设计与实验研究

 介绍了三角形栅格矩形径向线螺旋阵列天线的工作原理,设计并数值模拟了中心频率为4.0 GHz的三角形栅格矩形径向线螺旋阵列天线,并对此阵列天线进行了实验研究。实验结果表明：阵列天线在中心频率4.0 GHz 下,增益为15.3 dB,轴向轴比值1.58,驻波比为1.3,口径效率为86%;在3.8～4.2 GHz的频率范围内可实现圆极化定向辐射,增益大于14.9 dB,轴比值小于1.7,驻波比小于1.6。     

4单元矩形径向线螺旋阵列天线的理论分析和数值模拟

 提出了一种便于组合的矩形径向线螺旋阵列天线。介绍了该矩形阵列天线的提出背景以及工作原理,分析了L型电磁组合探针的耦合特性,设计并数值模拟了中心频率为4.0 GHz的4单元矩形径向线螺旋阵列天线。模拟结果表明：该天线易于实现单元天线激励幅度和相位的均匀性及其随频率变化的平坦性。该口径为90 mm×90 mm 的天线在中心频率4.0 GHz 下,方向性系数为12.57 dB,轴向轴比值1.55;在3.60～4.05 GHz的频率范围内方向性系数大于11.6 dB,轴比小于1.55,反射系数小于0.2。     

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.     

高功率微波行波阵列纵向宽角扫描特性

利用机械调节波导宽边尺寸可变化波导波长,从而实现变频波束扫描相同的效果,针对窄边辐射波导行波阵的波束扫描特性进行了分析,以实现宽角波束扫描为目标,着重分析了不同辐射缝隙间距下变化宽边所能得到的最大波束扫描范围。设计了通过变化宽边尺寸实现宽角扫描的X波段窄边辐射波导缝隙阵,设计波束扫描范围指向波导馈入端,避开阵列法向辐射(此方向辐射效率较低),实现了29°的连续波束扫描范围,在波束扫描范畴内增益下降小于3 dB,辐射效率大于62%;设计缝隙宽度3 mm, 波导长度约1 m(缝隙数40),单根波导缝隙天线可实现高功率微波功率容量70 MW。     

DIELECTRIC EFFECT ON THE RADIO-FREQUENCY CHARACTERISTICS OF A RECTANGULAR WAVEGUIDE GRATING TRAVELING WAVE TUBE

A new type of partial-dielectric-loaded rectangular waveguide grating slow-wave structure (SWS) for millimeter wave traveling wave tube (TWT) is presented in this paper. The radio-frequency characteristics including the dispersion properties, the longitudinal electric field distribution and the beam-wave coupling impedance of this structure are analyzed. The results show that the dispersion of the rectangular waveguide grating circuit is weakened, the phase velocity is reduced and the position of the maximum E _z is basically invariant after partially filling the dielectric materials in the rectangular waveguide grating SWS. Although the coupling impedance decreases a little, it still keeps above 40 Ω.     

Ka波段8路径向波导空间功率分配(合成)器

通过理论研究以及高频仿真相结合的方法分析设计了一款新型Ka波段8路径向波导空间功率分配(合成)器。研发的新结构输入输出段为标准矩形波导结构,代替了传统功率分配(合成)器输入输出段的同轴结构,这种新型全金属结构更加简单紧凑,更易于加工。仿真结果表明:功率分配(合成)器工作带宽达到了34%(12GHz),基本覆盖整个Ka波段;全频带内反射系数S11低于-20dB,各支路的相位差均小于5°。通过在同轴波导渐变段引入切比雪夫渐变结构,在减小了器件尺寸的同时,在整个频带内的网络S参数也不错。这款新型Ka波段8路径向波导功率分配(合成)器将应用于前级固态功率放大器,推动回旋行波管项目研发。     

X波段16单元矩形径向线螺旋阵列天线设计

研究了一种X波段16单元矩形径向线螺旋阵列天线。介绍了该矩形阵列天线的提出背景以及工作原理,分析了两种电磁耦合探针在X波段的耦合特性,开展了扼流结构与电磁耦合探针的协同设计,设计并数值模拟了中心频率为9.3 GHz的16单元矩形径向线螺旋阵列天线,并进行实验测试。测试结果表明:该口径为96 mm×96 mm的天线在中心频率9.3 GHz下,增益为19.51 dB,轴向轴比值1.05,驻波系数1.17。     

W波段基片集成波导缝隙阵天线的研究

介绍了一种低成本高效率的W波段4×4基片集成波导(SIW)缝隙阵天线。天线阵为双层结构,上层为辐射层,采用宽边纵向偏移缝隙驻波阵,可以实现高的辐射功率,下层为馈电层,采用SIW串联缝隙馈电方式,减小了传统功分网络带来的传输损耗和实现难度。对天线阵进行了优化设计,采用标准低成本PCB工艺制作了天线阵实物样品并进行测试。测试结果与仿真结果吻合较好,天线阵在94 GHz时,最大增益为16.8 dB,反射系数-30.1 dB,-10 dB带宽为92.6~96 GHz,副瓣电平19.5 dB,天线阵口径效率为83%。     

Numerical analysis for millimeter wave slot type coupler

The numerical analysis for millimeter wave slot type coupler of overmode waveguide cavity is studied by mode-matching taking account of the thickness of the plate on which the slot is cut. It is found that the higher modes in cavity can be suppressed by proper thickness of the plat and proper dimension of the output waveguide.     

波导缝隙阵列天线高功率微波应用探索

设计了一种波导窄边缝隙天线阵,其微波传输工作于行波状态,绝大部分能量被缝隙耦合辐射,其余能量被匹配负载吸收。通过等效电路的方法,使得各个缝隙达到均匀辐射,从而具备可拓展组阵能力,此外通过设计移相结构改变相位差,实现方位角方向的波束扫描。该缝隙天线工作在行波状态,避免了电场集中现象的出现,且工作于真空环境,具有较高的功率容量。     

扇形波导谐振宽边纵缝的归一化电导

扇形波导可作为高功率微波圆柱共形波导缝隙阵天线的基本单元。分析了扇形波导中主模场分量,根据实际情况对主模场进行了合理近似。采用互易定理推导由波导主模横向场分量和缝隙场分量表示的波导场分量的前向或后向散射系数。根据波导传输线理论,将波导宽边纵缝等效为并联导纳,再根据波导边界条件得到扇形波导宽边谐振纵缝的归一化电导与波导散射系数之间的关系式。根据缝隙天线与振子天线的互补关系得到扇形波导谐振缝隙的辐射阻抗,结合波导功率平衡关系得到由波导横向场散射系数表示的缝隙辐射功率表达式,得到归一化电导的与谐振宽边纵缝的偏移位置、缝隙宽度、波导波长以及扇形波导尺寸参数之间的解析表达式。给出了算例,在波导中间区域,通过商用软件计算得到的电导与理论公式结果基本吻合。     

Sliding backshorts for planar circuits

The Superconductor-Insulator-Superconductor (SIS) tunnel junction is an extremely sensitive heterodyne detector at millimeter and submillimeter wavelengths. The large inherent capacitance associated with this device results in a substantial impedance mismatch with typical antennas and, therefore, requires a tuning circuit for optimum results. At frequencies where waveguide dimensions are realizable, impedance matching can be accomplished by embedding the detector in a waveguide circuit with adjustable waveguide backshorts. At higher frequencies, where waveguide dimensions become prohibitively small, a planar transmission line embedding circuit provides a reasonable alternative. Typically, such planar circuits offer no post-fabrication adjustability, resulting in demanding materials and design requirements. An adjustable planar embedding circuit based on coplanar transmission lines with movable noncontacting shorting elements has been developed. The shorting elements each consist of a thin metallic plate with an optimized arrangement of rectangular holes, placed along the insulated metallic transmission line to provide a periodic variation of the line impedance. A scadel (1–5 GHz) has shown that a large reflection coefficient, |s ₁₁|–0.5 dB, can be achieved with these sliding elements. A low frequency tuning circuit incorporating these shorting elements has been tested to demonstrate practical tuning ranges.