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Multiplexer vs Power Divider

Both Multiplexers and Power Dividers are helpful devices to expand the number of antennas that can be connected to one reader’s port. One of the main benefits is to reduce the cost of a UHF RFID application by sharing expensive hardware. In this blog post, we explain the differences and what needs to be considered when selecting the right device for your application.

What are a multiplexer and a de-multiplexer?

To understand what an RFID reader Multiplexer is we will quickly explain the general purpose of multiplexers (mux) and de-multiplexers (de-mux).

A multiplexer is a device that selects one of the several input signals and forwards it to an output.

A demultiplexer is a device that forwards an input signal to one of the several outputs.

Both multiplexer and de-multiplexer require switches to select the inputs and/or the outputs. These switches are powered, and thus mux and de-mux are active devices.

What is an RFID reader multiplexer?

An RFID reader multiplexer is a device that is a combination of a mux and a de-mux. It consists of one input/output port and many output/input ports. A single port of a mux/de-mux is usually connected to an RFID reader while the multiple ports are dedicated for the antenna connection.   

It either forwards the signal from the RFID reader’s port to one of the several output ports or forwards the signals from one of the several input ports to the RFID reader’s port.

A built-in switch takes care of the signal switching between the ports and its switch timing.

The RFID multiplexer enables multiple antenna connectivity to a single port of the RFID reader. The magnitude of the signal switched is not affected significantly, regardless of the number of ports in a mux/de-mux.

That way, an 8-port RFID multiplexer, for example, can extend a 4-port reader into a 32-port RFID reader.

Some brands also call their mux a hub.

What are a power divider (power splitter) and a power combiner?

A power divider (splitter) is a device that divides the power. A 2-port power divider divides the input power into two outputs. The magnitude of the power is halved in the output ports.

The power divider is called a power combiner when used in reverse.

Here is a quick overview of the differences between a mux and a power divider:

A mux will have constant power loss across the ports regardless of the number of ports. A 4-port, 8-port, and a 16-port mux will not have different losses per port. A power divider would divide the power into ½ or ¼ depending on the number of available ports. A greater power reduction is experienced in each port as the number of ports is increased.
A mux is an active device. It requires DC power and control signals to operate. A power divider is a passive device. It does not need any extra input than the RF input.
Not all ports in a multi-port mux are turned on at the same time. The RF power is switched between the ports. Only one connected antenna will be energized at a time, and the switching speed is so fast that the antennas will not miss a tag read. All the ports in a multi-port power divider get the power equally and at the same time.
Very high isolation between the ports is achieved. This is essential to avoid cross-tag reads between the antennas. Isolation is usually in the range of 35 dB or more. The port isolation is little less compared to a Mux. Typical port isolation is around 20 dB or more. Cross tag reads may become an issue.
Has minimal or no impact in antenna’s beam or cancellation. When the power divider is not used in the right way, RF fields can get canceled, and the antenna’s RF beam can be altered significantly.
No RF expertise required to install a Mux. The Mux will have to be controlled by the RFID reader`s software. RF expertise is essential to install the power dividers and to achieve a working solution. An incorrectly installed power divider would dramatically spoil the performance  of the RF.
No custom antenna alteration is possible Custom antenna alteration is viable. Antenna`s beam-width, beam angle, etc. can be changed.

Si Chuan Keenlion Microwave a large selection, covering frequencies from 0.5 to 50 GHz. They are designed to handle from 10 to 200 watts input power in a 50-ohm transmission system. Cavity designs are utilized, and optimized for best performance.

Many of our products are designed such that they can be screw-down mounted to a heatsink, if necessary. They also feature exceptional amplitude and phase balance, have a high power handling, very good isolation levels and come with a rugged packaging.

We can also customize the rf passive product according to your requirements. You can enter the customization page to provide the specifications you need.

Post time: Oct-28-2022