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本文翻译自Microwaves101 | Microwave Rules of Thumb，汇总了一些微波电路中的经验法则（Rules of Thumb），所谓经验法则，就是一些长期总结出来的规律，多数情况下适用，但并不是任何时候都适用，请读者自行斟酌。
To be considered in "small signal operation", a signal should have less than 5% effect on the voltage bias point of an amplifier or diode or whatever nonlinear element is first affected. Not so sure how this would apply this to a zero-bias detector…. anyone want to comment?要想视为“小信号工作”，信号对放大器、二极管偏置点或者任何首先受到影响的非线性器件的影响应该小于5%。但是还不太确认本条规则如何适用于零偏置状态的检波器……有人想要发表观点吗？
In slow wave structures using alternate high and low impedance segments, the Bragg frequency occurs when the segments are 30 electrical degrees.采用高低阻抗线段的慢波结构中，布拉格频率出现在线段电长度为30deg时。
In slow wave structures using alternate high and low impedance segments, the line segments should be 5 electrical degrees or less at your maximum operating frequency.采用高低阻抗线段的慢波结构中，线段电长度在最高工作频率下应该小于5deg。
The Bragg frequency of an artificial transmission line occurs where the unit cell is 1/3 of a wavelength.人工传输线的布拉格频率出现在基本重复单元为1/3波长时。
TEM transmission line, loss tangent of 0.01 (which is pretty high) results in almost exactly 1 dB/cm loss at 110 GHz, before you scale it by SQRT(dielectric constant). Since it is linear with frequency, you should be able to scale loss tangent attenuation in your head. You can approximate attenuation in microstrip or CPW if you scale by the effective dielectric constant.对于TEM传输线，0.01的损耗角正切（很高）会导致1dB/cm@110GHz的损耗，还需要再乘以介电常数的平方根。由于是随频率线性变化的，可以用有效介电常数来估算微带线或者共面波导的正切损耗。
The 90% rule: coax is never specified to operate beyond 90% of its TE11 cutoff frequency.90%法则：同轴线绝对不能工作在超过其TE11介质频率的90%。
In order to achieve perfect cancellation of identical poorly-matched amplifiers, there are two necessary and sufficient conditions:
The coupler must provide perfect amplitude balance
The coupler must provide perfect 90 degree coupling
Perhaps more interesting is this: the termination resistor VSWR does not matter when you are considering only the VSWR of the combined amplifier.为了使相似的匹配不佳的放大器（驻波）理想对消，有两个充分必要条件：
耦合器必须提供理想的幅度平衡度；
耦合器必须提供理想的90deg耦合；
或许更有意思的是：当你仅仅是考虑放大器合成的VSWR时，端接吸收电阻的VSWR并不重要。
To convert Nepers to decibels, multiply by (approximately) 8.68.
More accurately,将奈培（Np）换算成dB，只需要乘以8.68，更精确的算式：
dB/Np = 20/ln(10)=8.68588
How many sections do you need in a Wilkinson power splitter? Divide the center frequency by the lowest frequency and the answer is revealed. Thus, for 2-18 GHz, plan on five sections.Wilkinson功分器需要多少节？用中心频率除以最低工作频率就得到答案了，比如2-18GHz的Wilkinson功分器用5节就行了。
Generally, waveguide wave impedance is approximately 500 ohms for standard rectangular waveguide. Wave impedance goes to infinity at cut-off, and has a downward slope in-band.一般来说，标准矩形波导的波阻抗大概是500Ω，截止频率处的波阻抗为无穷大，往带内走呈滚降趋势。
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