Method for manufacturing embedded variable capacitors in low-temperature cofired ceramic substrate

A method for manufacturing embedded variable capacitors (varactors) inside a low-temperature cofired ceramic substrate is presented. A varactor is fabricated by filling a via hole with ferroelectric barium strontium titanate paste. The measured capacitance of the varactor changed from 1.47 to 0.97 pF and the Q factor from 18.2 to 31.5 at 1 GHz when the bias voltage was increased from 0 to 200 V.     

Radiation from a ferrite-filled rectangular waveguide with multiple slits

Radiation from a ferrite-filled waveguide with multiple thick slits is investigated. The Fourier transform and mode matching are utilized to obtain a rigorous solution. The effect of the ferrite linewidth is included to account for the magnetic loss of ferrite. The maximum beam steering ratio 4.33/spl deg//100 oe is achieved with the magnetic bias field ranging from 1000 to 1400 oe. The ferrite-filled rectangular waveguide with nine slits is fabricated and its radiation patterns are measured at X-band. Our computational results agree with measurement data.     

波导二极管移相器的设计

介绍了波导二极管移相器的设计原理和实现方法。运用矩形波导的传输理论,将加载线型移相单元插入矩形波导内,对波导内的24个加载线型移相单元进行调配组合实现五位地址数码控制移相器。实测结果表明该移相器移相范围大、插入损耗低、输入驻波小、转换时间快、移相精度高及耐高功率性好。     

Coplanar waveguide phase shifter controlled by a spatially periodic optical illumination

The characteristics of a periodically-illuminated CPW phase shifter are investigated by the spectral domain approach combined with the cascaded transmission line matrix method. It is found that the phase shifter characteristics can be improved by appropriate use of periodic illumination instead of uniform illumination.     

Microwave ferrite toroidal phase shifter in grooved waveguide withreduced sizes

Ferrite toroidal phase shifters in both rectangular and ridge waveguide were studied theoretically and experimentally. The influences of various parameters on the performance of the phase shifter are calculated and discussed. Theoretical analysis shows that, with proper choice of dimensions, the phase shifter may be made very broadband and the loss of the phase shifter may be reduced 16% when compared to the case using rectangular waveguides. The phase shift versus frequency characteristics of these two models are shown graphically. The loss factors are approximately 0.8-1.0 dB/360°. The experimental results are in good agreement with theory     

Improved analysis of nonreciprocal remanence ferrite phase shifter in grooved waveguide

In this paper, the nodal finite-element method is used to analyze the differential phase shift of a nonreciprocal remanence ferrite phase shifter in a grooved waveguide. Instead of the former twin-slab model, an improved analytical model is adopted, where the effect of every part of a ferrite toroid on the differential phase shift has been considered. This analysis may replace the correcting factor with good agreement with the experimental data. Furthermore, this analysis is employed to investigate the effect of corner chamfering on the figure-of-merit (differential phase shift per decibel insertion loss) of a ferrite phase shifter. The numerical results are found to agree with the experiments in the literatures.     

A 2-bit RF MEMS phase shifter in a thick-film BGA ceramic package

The development of a thick-film hermetic BGA package for a radio-frequency (RF) microelectromechanical systems (MEMS) 2-bit phase shifter is presented. The measured packaged MEMS phase shifter average in-band insertion loss was 1.14 dB with an average return loss of 15.9 dB. The package transition insertion loss was less than 0.1 dB per transition with excellent agreement between simulated and measured results. It was also demonstrated that the RF MEMS phase shift performance could be improved to obtain a phase error of less than 3.3 degrees. The first reported measurements of the average rise and fall times associated with a MEMS circuit (in this case a 2-bit phase shifter) were 26 and 70 /spl mu/s, respectively. The advent of packaged RF MEMS phase shifters will reduce the cost (both design and building) of future phase arrays.     

有限量化精度移相器对毫米波平面相阵波束控制性能的影响

在毫米波频段由于路径损耗较大,通常采用波束成形来提高链路增益以建立稳定的连接。通常在低频段采用的数字波束成形,由于每根天线配置一条射频链路,功耗和成本较高。采用相阵架构实现射频波束成形是一种折衷的选择。本文研究了毫米波信道下移相器有限的量化精度在平面相阵单流波束控制（beam steering）中带来的性能损失。首先推导了阵列增益损失与移相器误差方差之间的理论关系,然后通过蒙特卡洛仿真验证该理论结果。从仿真结果可以看出平面相阵的增益损失可以通过增加移相器精度来减小。在通常应用中,4-bit移相器在实现平面相阵波束控制时提供了足够的增益。      

Analysis of a rectangular waveguide isolator

Isolator conditions are derived for a rectangular waveguide in which magneto-optical and anisotropic dielectric crystals are integrated for reciprocal and nonreciprocalE^{x}-E^{y}mode conversion functions, respectively. Relations between structural parameters are derived by perturbation analysis, and design examples of single-mode isolators with 3.6-, 4.6-, and 6.6-μm square cores are given at the 1.55-μm wavelength. Tolerances in the structural parameter deviations are investigated analytically and numerically. Isolation of more than 20 dB is feasible without any parameter adjustment even when there is a 9- percent deviation in the core dimension.     

Radiating apertures in a corrugated rectangular waveguide

A variational analysis for determining the scattering parameters of an aperture in the plane broad wall of a corrugated rectangular waveguide is described. To effect the analysis, a quasi Green's function for the loaded waveguide is postulated.     

Scattering by a dielectric obstacle in a rectangular waveguide

A method for the computation of S-parameters associated with a rectangular waveguide with a rectangular or cylindrical obstacle of arbitrary complex scalar permittivity is presented. The method uses modal analysis and integral relationships to connect appropriate components of the field. In this way, convergence is achieved faster than by point-matching techniques. Our method is well adapted to resonance problems, as illustrated by comparison with both theoretical and experimental results     

Analysis of a coaxially fed monopole in a rectangular waveguide

The boundary-value problem of a coaxially fed monopole in a rectangular waveguide is solved. The technique of image method is applied to transform the original problem into an equivalent problem. A fast convergent series solution based on the Fourier transform and mode matching is presented. Our computation results compare favorably with other existing data.     

Admittance of rectangular waveguide radiating from a conductingcylinder

Theory and experiment are compared for the admittance presented to a rectangular waveguide which terminates at an arbitrary angle in the surface of a conducting cylinder. Two methods are described for calculating the admittance: a single-mode approximation from the modal solution and an alternative asymptotic solution. Using these methods, the effect of aperture orientation on admittance, and the results obtained are compared with the experiment. The single-mode approximation is in good agreement with experimental results for the case when the input waveguide supports the TE₁₀ mode only. The accuracy of the approximate formula for waveguide admittance was also verified. The admittance is shown to be weakly dependent on aperture orientation for moderately large cylinders     

Mode-matching analysis of a shielded rectangular dielectric-rod waveguide

Rectangular cross-sectional dielectric waveguides are widely used at millimeter wavelengths. In addition, shielded dielectric resonators having a square cross section are often used as filter elements; however, there is almost no information available on the effect of the shield. Rectangular or square dielectric waveguide is notoriously difficult to analyze because of the singular behavior of the fields at the corners. Most published analyses are for materials with a low dielectric constant, and do not include the effects of a shield. This paper describes a numerically efficient mode-matching method for the analysis of shielded dielectric-rod waveguide, which is applicable to both low and high dielectric-constant materials. The effect of the shield on the propagation behavior is studied. The shield dimensions may be selected such that the shield has a negligible effect so that results can be compared with free-space data. The results are verified by comparison with several sets of published data, and have been confirmed by measurement for a nominal /spl epsiv//sub r/ of 37.4.     

Attenuation of a shielded rectangular dielectric rod waveguide

The attenuation coefficient of a rectangular dielectric line enclosed by a rectangular shield is obtained by the use of a rigorous mode-matching method to calculate the required mode field intensity. The cross section of the waveguide is overlaid by a grid, and numerical integration is used to determine the power flow, dielectric, and conductor losses and respective attenuation coefficients. To obtain experimental verification, a length of waveguide was made into a resonator, and measured and calculated Q factors were compared. The results for the E/sup y//sub 11/ mode show how the influence of the shield decreases with distance. This is relevant to the design of dielectric waveguide structures and in filter applications where dielectric resonators are used.     

Fast convergent dyadic Green's function in a rectangular waveguide

Alternative formulas for the dyadic Green's function in a rectangular waveguide are presented. These new functions are deduced by modifying part of Rahmat-Samii's derivation procedures by employing the Poisson summation technique. The Green's function obtained owns fast convergence property and is proved to be more suitable for numerical applications.     

Coupling of an open resonator and a rectangular waveguide through a smooth waveguide transition

Under investigation is a coupling element for coupling an open resonator to a rectangular waveguide and consisting of a smoothly irregular waveguide section conjugate to a narrow slot in a mirror, A technique for the determination of the coupling Q-factor is proposed and good agreement between calculations and experimental results is obtained. Based on such a coupling element, an open resonator has been well matched with a waveguide and made retunable in a wide frequency range without coupling adjustment..     

含半导体超常媒质的矩形波导的导模研究

采用改进后的马可梯里方法推导出了半导体超常媒质矩形波导中体模和表面模的色散方程,讨论了最低阶TM模的截止频率并画出了布里渊图。结果显示不同的波导高度具有不同的导模频带,波导高度大的对应的导模频带较宽,并且彼此之间没有重叠。除此之外,不同模式还存在着简并的趋势。最后采用作图法验证了表面模的存在性。