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。
The graceful degradation of gain in an N-way combiner used in a power amplifier decreases as [(N-X)/N]^2 where X is the number of failures. Half the gain is lost on the input, and half on the output. If you can provide the equivalent increase in input power, the output power will drop as (N-X)/N. This assumes ideal conditions, at center frequency, and an isolated power splitter is used (such as a Wilkinson).功率放大器采用的N路合成器增益（损耗）按[(N-X)/N]^2规律减小（增大），其中X是失效路数。输入输出网络损耗各占一半。如果输入功率增加相同量（损耗的一半），则输出功率就只下降(N-X)/N。这是假定在理想条件下、在功分器的中心频率处、功分器是隔离型的（例如Wilkinson）的前提下。
This came from JC... the only thing that HBTs have been good for is being cheap and having lower phase noise for VCOs. Otherwise short gate length pHEMTs are better in every other respect....HBT的唯一优点就是便宜、设计VCO相噪更低，否则短栅长pHEMT器件在其他各个方面都更优……
The number of elements required in an electronically-scanning phased array antenna can be estimated by the gain it must provide. A 30 dB gain array needs about 1000 elements and a 20 dB gain array needs about 100. Thanks to Glenn!电扫描式的相控阵天线所需的阵元数可以由所需增益估算：30dB增益的阵列需要大概1000个阵元，而20dB的阵列需要大概100个阵元。
Numbers 94 to 100 are from Tom. Thanks for putting us over the top! On Microstrip layers, keep ground fill at least 3 line widths away from the microstrip to maintained the originally designed impedance. This means if the line width is 10 mils keep the ground on that layer at least 30 mils away or you'll have a mismatched co-planar waveguide!在微带布线层，一定要保持铺地离微带线三倍于线宽的间距才能保持原始设计阻抗不受影响。即如果微带线宽度为10mil，则铺地离微带线要保持至少30mil，否则你就会得到一个失配的共面波导！
Guesstimating wavelength in free space is always a race to see who can think faster. Just remember that 300 MHz is 1 meter and ratio your way from there. So 1 GHz is approximately 3 times 300 MHz so the wavelength is approximately 1/3 or 30cm OR 100 MHz is 3 meters.估算自由空间的波长总是考验谁算的更快，只需记住300MHz对应1m波长，依次进行缩放就行了。比如1GHz大概是300MHz的3倍，因此波长就是1/3即30cm；或者说100MHz对应波长是3m。
If your circuit does funny things when you close up the box, it's oscillating. If you can't see it on the spec-an then it's above the instrument range.如果你的电路在盖上外壳后就变得莫名其妙了，那么它振荡了。而如果你在频谱以上看不到（振荡频谱）那么肯定是（振荡频率）超过了频谱仪的频率范围。
If your circuit is oscillating when the cover is on, stick 1 square inch of absorber material (the adhesive backed stuff) stripe down the middle of the inside roof of the cover for every 3 sq. inches of cover. It doesn't much matter what the thickness is although you can adjust that later when you write the ECO.如果你的电路在盖上盖板后振荡了，在盖板顶部中央每3平方英寸贴一块1平方英尺的吸波材料（背面可粘贴的那种），厚度倒是不太重要，不过你可以等写设计更改单时再明确。
Tom's Law: in any broadband (>1 octave) design, the overall gain/attenuation will be about 0.75 dB/GHz worse than expected by design calculation or simulation. You've been warned so plan ahead.任何宽带（大于一个倍频程）的设计中，整体的增益/衰减大概会比设计值或者仿真差0.75dB/GHz，警告过你了，因此提前考虑好！
Gain in a microwave chain is like a gun. Better to have it and not need it than to need it and not have it.微波链路的增益就像一把枪——宁可有了不用，也不能在需要的时候却没有。
Switched filter phase shifter bits, either high pass, or low pass, are not useful above 90 degrees of phase shift. For a 180 bit, you must cascade two 90s, or use an alternate structure. The preferred structure is a high-pass/low-pass bit.开关滤波器式的移相单元，无论是高通还是低通，都不能用于超过90deg的移相。对于一个180deg的移相单元，你只能级联两个90deg，或者采用其他结构，比较偏好的结构是高低通开关切换式移相单元。
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