Xiaobai talks about measuring instruments - RF power meter

definition

RF power meters are used to measure the power in RF circuits. We can choose different ways to measure power according to different applications.

RF power is a critical parameter in many applications, so RF and microwave power meters are needed in RF development, design, testing, service repair and field service.

RF power measurement can be performed in many ways, each with its own advantages and disadvantages. In actual work, we must choose the correct form of power measurement to obtain correct test results.

Types of RF and Microwave Power Meters – Through-Type and Absorption

Power meter

This type of power meter samples the signal on the main line through the feedback line and indicates the actual power level passing through the main line. These through-type power meters are used directly on the transmission system line to check the status of the output power in real time. They are usually directional and can be used to check the power propagation in any direction.

Generally speaking, through-type power meters are not frequency sensitive; they measure the total input power.

Absorption RF Power Meter

As the name implies, these RF power meters absorb the power they measure. Simple power meters are analog type meters that combine a power absorbing RF load, a sensitive diode, and an analog dial. These power meters are adequate for many applications, but they are limited in some performance aspects.

More advanced power meters generally have an external power sensor that is connected directly to the power generator during testing, and there are many types of these power sensors. These sensors produce signals proportional to the measured power, which are fed into the power meter host for processing and the results are displayed in digital form.

Absorption RF power meters are also frequency insensitive; they measure the total power entering them.

Today, with the rapid advancement of digital signal processing capabilities, many RF power meters include extensive data processing capabilities to measure the power levels of a variety of signal types.

When choosing an RF power meter, it is important to choose the right type of power sensor. There are many different types of power sensors, which are suitable for different types of RF power measurements. Some types of RF power sensors are suitable for measuring average power, while other types can measure pulse power or peak envelope power.

Spectrum analyzers and other instruments

Instruments such as spectrum analyzers also have power measurement capabilities. These instruments are able to measure the RF power level at a specific frequency, but cannot measure the total power of all input signals.

The spectrum analyzer measures power with frequency sensitivity, which means it can measure the signal power at a specific frequency. This is very useful when you need to measure the power of the fundamental frequency, harmonics, or other spurious signals.

Different types of RF power meters are selected according to actual conditions. Generally speaking, absorption-type RF power meters are used for precise laboratory measurements, while through-type power meters are often used more in field applications.

Summarize

It can be seen that RF power meters or microwave power meters are essential for development engineers, service engineers, and field engineers in many fields. No matter what form the RF signal exists in, in order to accurately measure its power level, choosing a suitable power meter for measurement is the best way. In some cases, a spectrum analyzer can also be used, but to obtain the best power level, it is recommended to use an RF power meter for measurement.