Methods for measuring high frequency voltage and current

1. Measurement of high frequency voltage

In order to analyze the influence of the voltmeter on the measured circuit, we study the equivalent circuit of the voltmeter. The larger the ci of the voltmeter, the smaller the c of the loop, and the more serious the detuning of the loop; the input resistance ri is connected in parallel to the loop, which will change its working state. The smaller ri is, the more significant the change in working state is.

2. The voltmeter voltage used for high-frequency measurement should have the following characteristics

(1) Within a wide frequency band, the reading has little to do with the frequency of the voltage being measured.

(2) The influence on the working state of the measured source is small. In other words, the input resistance should be large (the input capacitance should be small).

(3) The voltage measurement range is wide and the sensitivity is high.

(4) The reading establishment time is short.

(5) Ability to withstand overload (the voltage at the input end of the voltmeter exceeds the allowable value).

3. Measurement of high frequency current

【example】

The ammeter should be connected at the lowest point, where it causes the least reaction in the circuit being measured.