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## 电气工程代写|射频电路代写RF Circuit代考|Passive Modeling

Lumped or surface-mount elements are attractive due to their small size, broad bandwidth, and commercial availability compared with distributed elements. At low frequencies, component size is very small compared to the wavelength. Therefore, they can be used with minimal concern. However, at higher frequen- cies (UHF and above), this is not the case. Lumped elements exhibit spurious resonances, fringing fields (radiation leakage), loss, and other parasitic (undesired) effects (discussed in Chapter 6) [1].

## 电气工程代写|射频电路代写RF Circuit代考|Capacitor

The equivalent circuit model of a lumped-element capacitor is shown in Figure $3.1$ where $C_{n o m}$ is the nominal capacitance, $L_s$ is the series parasitic inductance, ESR is the equivalent series resistance, and $C_p$ is the parallel parasitic capacitance.

Fortunately, data sheets often include one or more of these parameters to aid designers. If not, S-parameters are usually available so that values can be tuned to match the frequency response. Figure $3.2$ shows the effect $L_s$ has on the capacitor frequency response. The $L_s=0.000$ curve has no parasitic effect. As $L_s$ increases, the high-frequency response degrades quickly.

Some components are marketed as having “low ESR.” They are designed for high-frequency applications. Having a low ESR will reduce the loss, especially at high frequency.

Sometimes data sheets quantify the loss of capacitor by its quality factor $(Q)$, which is defined as:
$$Q=\frac{1}{2 \pi f C_{\text {nom }} \cdot E S R}$$

where $f$ is the frequency (hertz), $C_{\text {nom }}$ is the nominal capacitance (farads), and ESR is the series resistance $(\Omega)$. This equation can be used to calculate ESR.
Data sheets may also specify the series-resonant frequency (SRF) of a capacitor. This is the frequency where $C_{n o m}$ and $L_s$ are equal, but opposite in magnitude. At that frequency, the capacitor behaves like a parallel RC circuit with $E S R$ and $C_p$. To calculate $L_s$ from $S R F$, the following equation can be used:
$$L_s(\mathrm{nH})=\frac{1000}{4 \pi^2 C(\mathrm{pF}) \cdot \mathrm{SRF}(\mathrm{GHz})^2}$$
$C_p$ accounts for any deviation from the frequency response that cannot be predicted. It is determined by trial and error until the measured frequency response matched the equivalent circuit model.

## 电气工程代写射频电路代写RF Circuit代考|Capacitor

$$Q=\frac{1}{2 \pi f C_{\text {nom }} \cdot E S R}$$

$$L_s(\mathrm{nH})=\frac{1000}{4 \pi^2 C(\mathrm{pF}) \cdot \mathrm{SRF}(\mathrm{GHz})^2}$$
$C_p$ 解释无法预则的频率响应的任何偏差。它是通过反复试验确定的，直到测得的频率响应与等效电路模型相匹配。

## MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。

Posted on Categories:RF Circuit, 射频电路, 电气工程代写

## avatest™帮您通过考试

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## 电气工程代写|射频电路代写RF Circuit代考|Material Selection

It probably goes without saying that material selection is critical in every aspect and discipline of engineering. No one would ever make a bridge out of paper mâché or an airplane out of brick. Materials must be chosen based on the following factors:

Physical properties (i.e., melting point and reflectivity);

Electrical properties (i.e., conductivity, dielectric constant, and loss tangent);

Mechanical properties (i.e., Poisson’s ratio and fatigue resistance);

Thermal properties (i.e., thermal expansion, specific heat, and conductivity);

Chemical properties (i.e., corrosion, radiation, and oxidation resistance);

Manufacturing properties (i.e., machinability and available tolerances);

Cost (i.e., whether it meets the financial requirements);

Availability (i.e., whether it can be procured in the time allowed);

Environmental impact (i.e., whether it contains lead).
Guidelines for material selection will be discussed throughout the book. It is a design parameter that is especially critical for radars due to these inherent characteristics of radar:

Concentration of heat in small areas;

Fluctuation of electrical and environmental conditions;

Requirements for cost reduction;

Low tolerance for failure;

Severe operating conditions.
This section provides an overview of materials commonly used in component design. The appendix lists tables of material properties.

## 电气工程代写|射频电路代写RF Circuit代考|Semiconductors

Semiconductors provide the backbone for monolithic microwave integrated circuits (MMICs), which are the RF equivalent of the integrated circuits found in everyday digital chips. Common semiconductors used in microwave radar components include Gallium Arsenide (GaAs) and Gallium Nitride (GaN). Semiconductors tend to have the following material characteristics [5]:

• They are poor conductors of electricity;
• They have a high temperature stability;
• Their purity can be implemented to within a few impurity atoms for every billion host atoms (parts-per-billion, ppb);
• They are chemically resistant.

## 电气工程代写|射频电路代写RF Circuit代考|Semiconductors

• 它们是电的不良导体；
• 它们具有高温稳定性；
• 它们的纯度可以在每十亿主原子的几个杂质原子内实现（十亿分之一，ppb）；
• 它们具有耐化学性。

## MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。

Posted on Categories:RF Circuit, 射频电路, 电气工程代写

## avatest™帮您通过考试

avatest™的各个学科专家已帮了学生顺利通过达上千场考试。我们保证您快速准时完成各时长和类型的考试，包括in class、take home、online、proctor。写手整理各样的资源来或按照您学校的资料教您，创造模拟试题，提供所有的问题例子，以保证您在真实考试中取得的通过率是85%以上。如果您有即将到来的每周、季考、期中或期末考试，我们都能帮助您！

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## 电气工程代写|射频电路代写RF Circuit代考|Introduction to Microwave Components

Microwave components are the building blocks for microwave assemblies, modules, subsystems, and ultimately systems. Passive components manipulate electrical signals without adding energy. Active components do the same, but they draw on energy from an external source and can thus potentially add energy (such as amplification) to a signal.
Fundamental Equations
The most fundamental behaviors of electromagnetics are described by Maxwell’s equations. Although compact and perhaps deceptively “simple,” they are extremely powerful in what they represent. A deep understanding of their usage is not necessary to be a good microwave designer, but they are referenced throughout the book [2]. A description of each follows.
Gauss’ Law for Electricity
An electric charge produces an electric field, and the flux of that field passing through a defined closed surface is proportional to the total charge within that surface, or:
$$\oint_S \vec{E} \circ \hat{n} d a=\frac{q_{e n c}}{\varepsilon_o}$$
where $\vec{E}$ is the electric field (Newtons/Coulomb), “ôn” indicates the portion of the field perpendicular to the surface, $d a$ is an increment of surface area $\left(\mathrm{m}^2\right)$, $q_{e n c}$ is the amount of charge within the surface (Coulombs, C), and $\varepsilon_o$ is the free-space permittivity.

## 电气工程代写|射频电路代写RF Circuit代考|Essential Components

Just as craftspeople must be familiar with their tools, microwave designers must understand the diversity of components at their disposal. Table $1.2$ lists the most common RF components in alphabetical order with a brief explanation. Design strategies for most of these, or portions thereof, are discussed in this book.

## 电气工程代写射频电路代写RF Circuit代考|Introduction to Microwave Components

$$\oint_S \vec{E} \circ \hat{n} d a=\frac{q_{e n c}}{\varepsilon_o}$$
C)，和 $\varepsilon_{0 \text { 是目由空间介电常数。 }}$

## MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。