微波电路经验法则121~127（完结）

The most RF wirebond inductance you can full resonate out in a simple low-pass structure is when the wire's reactance is equal to Z0. In a 50 ohm system, if you have a wirebond with j100 ohms impedance, you are looking at a significant impedance mismatch, with load-pull another potential problem.能通过低通滤波结构来最大限度地谐振掉射频键合线电感是当键合线的感抗等于Z0时。在50Ω系统中，如果你有一根阻抗为j100Ω的键合线，那么你正在面对一个巨大的阻抗失配，另一个潜在问题是存在负载牵引。

For silicon ICs you might encounter in chip-and-wire construction, you should plan on biasing the backside of the chip to the most negative voltage that is present on any of the die inputs.  For example, when mounting a negative voltage linear regulator where the input is -12V and the output is -5V,mount the die on a pad that is connected to -12V.  To be sure, check with the manufacturer's technical support group. 对于硅基集成电路，你可能会面临芯片走线的构造问题，你应该计划将所有输入电压中最偏负的那一个值作为偏置电压施以芯片的背部。例如，装配一个输入-12V、输出-5V的负压线性稳压电源时，将裸芯片安装（粘接）在连接到-12V的焊盘上。保险起见，最好再跟生产商的技术支持团队确认一下。

When power-combining two amplifiers using Wilkinsons in order to ensure graceful degradation, the isolation resistor in the input divider needs to be sized to be able to withstand 1/4 of the average input power.  The isolation resistor in the output combiner needs to be sized to withstand 1/4 of the average output power (or one half of the average power of a constituent power amplifier. This rule can be extended to corporate combiners by considering each Wilkinson separately.当使用Wilkinson功分器来对两个放大器进行功率合成时，为确保可忍受的性能降级，输入功分端的隔离电阻应该能够承受1/4的平均输入功率；输出功分端的隔离电阻应该能够承受1/4的平均功率（或者合成后总平均功率的1/2）。本条法则还可以延伸到多级/多路功率合成的情形，只需独立考虑每一个Wilkinson功分器。

For air coax operating at the onset of TE11, maximum peak power handling occurs at an impedance of ~44 ohms (more exactly, 44.327 ohms). At TE11 onset and 44 ohms, you can't get higher peak power handling unless you introduce a dielectric, which will increase loss.工作于TE11模式起始频率的空气同轴线，最大峰值功率容量在约44Ω（精确值是44.327Ω）时取得。因此在TE11模式的起始频率和44Ω条件下，你不可能获得更高的峰值功率容量，除非引入介质，这又会增加损耗。

For most practical purposes, an axial mode helix antenna has a 140Ω input impedance. If you need higher precision, don’t forget the imaginary part, and listen to you EM simulator.出于实用目的，轴向模螺旋天线具有140Ω的输入阻抗，如果你需要更高的精度，不要忘了阻抗的虚部，再求助于你的EM仿真器。

When designing a TRL calibration kit, the "line" standard needs to be between 20 and 160 degrees in phase length.  For a frequency span up to 8:1, only one line is needed.  Up to 64:1, two lines are needed. Up to 512:1, three lines are needed.  Up to 4096:1, four lines are needed.  If you need more 4094:1 frequency band, you (or whoever is asking you to do this) might consider therapy.设计TRL校准件时，“L”标准件需要介于20~160deg的电长度，在最大8:1的频率范围内只需要一个“L”标准；在64:1的带宽内需要两个“L”标准；在512:1的带宽内需要三个“L”标准；在4096:1的带宽内需要四个“L”标准；如果你需要超过4096:1的带宽，那么你（或者要求你这么做的人）也许有病需要治疗一下。

Considering two-way Wilkinson power dividers, worst-case dissipation in the isolation resistor can be easily calculated from the return losses seen by the two arms (harmonic balance is not needed). Assuming that the loads seen by both arms are 2:1 mismatch, 11% of the power will reflected back in, and in the worst-case situation it is all dissipated in the isolation resistor. You can figurethis out by noting that 2:1 VSWR is -9.54 dB return loss, and 10^(-9.54/10) is 11%. However, this only happens when the mismatches occur 180 degrees out of phase (if they are in-phase, reflected power will return to the Wilkinson input). Taken to the extreme, if the loads were 0 dB return loss and out of phase by 180 degrees (like an open and a short), the full incident power to the Wilkinson divider would dissipate in the isolation resistor (and the input of the Wilkinson would appear matched!)考虑两路的Wilkinson功分器，隔离电阻最坏热耗通过两个功分支路的回波损耗可以很容易计算（而不需要通过谐波平衡法来分析）。假设两个支路负载看到的支路失配驻波比为2:1,则11%的功率会被反射回去，因此最坏情况下这部分功率全部被隔离电阻消耗掉。你可以这样计算，2:1的VSWR即-9.54dB的回波损耗，换算成百分比10^(-9.54/10) = 11%。然而这种情况指在两个支路的失配刚好相差180deg相位的时候才会出现（如果同相，则功率会被反射回输入端）。往最极限的情况考虑，负载回波损耗为0dB且两路相位差180deg时（例如一个开路，一个短路），则Wilkinson功分器的全部入射功率都会被隔离电阻吸收掉（同时功分器的输入端口却表现为匹配状态！）