Passive devices are one of the two major categories in the field of RF microwave, passive devices include passive filters, power dividers and other microwave components that can work without external power supply.

Classification of passive devices

1.Coaxial Load

Coaxial loads usually have coaxial power loads and coaxial standard matching loads, and the main technical values are operating frequency range, return loss (standing wave ratio), power capacity and so on.

2. Attenuator

An attenuator is an electronic device that introduces a predetermined amount of attenuation within a specified frequency range, which can be used to control the level of the amplifier input/output, level control in the transmission link, and control the amount of branch attenuation.

3. Power Divider

The power divider is called the power divider, which is a device that divides the energy of an input signal into two or multiple equal or unequal energies, and can in turn synthesize the multiple signal energy into one output, which can be called a combiner. It is a reversible network that can be used either as an allocator or as a combiner.

4. Filter

The filter has a frequency selection function, which can divide the frequency, make the required frequency pass, and inhibit the unnecessary or harmful frequency signal, and the classification has the concentrated parameter filter, the microstrip line filter, the mechanical structure filter.

5. Directional Coupler

Directional coupler applications are:

① Part of the energy can be obtained by using directional couplers, which can be used to monitor power, frequency and spectrum.

② The reflectometer is composed of directional couplers, which can measure insertion attenuation, return loss, standing wave ratio, etc.

③ In the radar system, part of the energy in the main line is extracted with the directional coupler for debugging and measurement.

④ In mobile communication systems, especially indoor distribution systems, a large number of directional couplers are used to achieve system signal coverage.

⑤ When measuring power in microwave, the directional coupler is used to expand the measuring power range.

6. Diplexers

In the mobile communication system, when the mobile station (mobile phone), the base station, the repeater station, and the enhancement of the duplex work, the same pair of antennas can be provided to the transceiver at the same time through the antenna shared, and the requirements do not affect each other, the transceiver antenna shared, also known as the duplexer.

7. Multi-frequency Combiner

Multifrequency combiner is a device that combines different signals of multiple frequencies (such as GSM, CDMA, DCS, WCDMA, TD-SCDMA, etc.) on a transmission line, and the function of the splitter is the opposite.