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RF isolator principle

Time：2023-07-27

An RF isolator is a two-port device made of magnet and ferrite material to protect RF components or devices connected to one port from reflections from the other. For example, as described below, the signal source is used to feed the signal through the isolator to the device under test, which helps prevent damage to the signal source due to harmful reflections from the DUT.

As shown in the figure above, the RF isolator basically terminates the load on the third port of the circulator.

RF isolator type

RF isolators are mainly based on layout rather than function, and are available in both plug-in and coaxial types.

Embedded isolators are used in RF module designs using microstrip technology, where the input and output ports are matched on the microstrip PCB. Designed for RF transceivers, power amplifiers, LNAs, etc.

Coaxial or connector isolators are primarily used for RF testing of equipment.

The following summarizes the technical specifications of RF isolators for 4G/LTE applications.

• Frequency range: 700-800MHz

• Isolation: 20dB

• Insertion loss: 0.4dB

• VSWR：1.25

• Connector: SMA-Female

As stated in the specification, ports 1 through 2 have very little insertion loss, making it very easy for the signal to pass through. Port 2 through Port 1 provides 20dB of isolation, thus limiting where the reflected signal reaches Port 1, preventing corruption. In addition, any reflected signal is dissipated in the load connected on port 3.

RF isolators with high isolation and low insertion loss are the best choice for buyers. These types of RF isolators provide high performance in the system.

Keywords： RF isolator principle