Duplexer vs No Duplexer, How to Choose for Your Repeater?

When setting up a radio repeater system, some people hesitate between going with a repeater duplexer or not using a duplexer. In this article, we will explore the pros and cons of both approaches to help you make a decision.

Go with a Duplexer:

Duplexers play a crucial role in repeater systems, particularly in VHF (Very High Frequency) and UHF (Ultra High Frequency) frequency bands. These devices enable bidirectional communication on a single antenna by separating transmit and receive signals, eliminating interference and enhancing the efficiency of repeater systems. Here are the advantages and disadvantages of using a repeater duplexer in a repeater system.

Pros:

Simplicity: With a duplexer, there is no need to install and align separate transmit and receive antennas, streamlining the installation process.

Space and Cost Efficiency: By using a single antenna and antenna feeder cables, a duplexer helps minimize the hardware required, reducing installation costs and saving valuable space.

Improved Isolation: A properly tuned and high-quality duplexer can provide excellent isolation between the transmitter and receiver frequencies, reducing interference and maximizing system performance.

Cons:

Complexity in Tuning: Duplexers often require precise tuning to achieve optimal performance, which may require technical expertise or professional assistance.

Limited Frequency Separation: Duplexers have a specific frequency separation range they can handle effectively. If the transmit and receive frequencies are too far apart, a more complex and expensive duplexer might be required.

Potential Losses: Duplexers can introduce insertion loss, resulting in a slight decrease in overall system gain.

Not Use a Duplexer:

Using two separate antennas, one for transmit and one for receive, is an alternative approach for repeater installations that don't use a duplexer. Let's explore the advantages and disadvantages of this method:

Pros:

Enhanced Performance: By using high-gain antennas specifically designed for either transmit or receive, you can potentially achieve better signal quality and extended coverage.

Greater Flexibility: With two separate antennas, you have more control over antenna placement, allowing for optimal positioning to enhance coverage and reduce interference.

Improved Isolation: Using separate antennas inherently provides physical separation between the transmit and receive signals, minimizing the risk of interference.

Cons:

Increased Hardware and Cost: Utilizing two antennas requires additional hardware, such as mounts, antenna extender cables, and connectors, resulting in higher installation costs.

Space Constraints: Installing two separate antennas may be challenging in situations where space is limited, such as on small towers or rooftops.

Alignment and Maintenance: Aligning two antennas for optimal performance requires careful adjustment, and regular maintenance may be needed to ensure continued performance.

How to choose?

It will depend on a number of factors, including the physical location of the repeater, the desired coverage area, and the budget. If the repeater is to be installed in a location where it is difficult or impossible to install two antennas, and also if the budget is a concern, then a repeater duplexer may be the best option. When you prefer to use a repeater with built-in duplexer, we will recommend this hot-selling Retevis RT97S repeater with single antenna kit.

Retevis RT97S Portable GMRS Repeater Kit With FRP Antenna

If the repeater is to be used for longer range communications, then two antennas may be a better option. When you prefer to use a repeater without a duplexer, we will recommend this new Retevis R1 repeater with two GMRS antennas kit.

Retevis R1 25W Repeater (No Duplexer) with GMRS Antennas Kit