RF Terminations & Dummy Loads

What are RF terminations and dummy loads?

RF terminations and dummy loads are resistive loads designed to absorb the signal in a controlled way, simulate a properly terminated line and ensure correct impedance matching on RF ports and lines. They are used to close unused ports, terminate the outputs of power dividers, create dummy loads for test setups, and verify the response of RF, microwave and mmWave systems under defined conditions.

This category includes both coaxial terminations and waveguide terminations, available in different power ratings, frequency bands and mechanical interfaces to match the main system architectures.

RF coaxial terminations

RF coaxial terminations are resistive loads in connectorised format, typically with a nominal impedance of 50 Ω or 75 Ω, mounted directly on standard RF connectors (such as SMA, N, 2.92 mm, BNC, etc.). They are used in test instruments, benches and telecom systems to:

• terminate unused ports on power dividers, combiners and directional couplers;
• implement dummy loads for power testing on transmitters and amplifiers;
• properly terminate RF lines during VSWR, return loss measurements and calibrations;
• ensure well-defined load conditions on sensitive output stages.

Coaxial terminations are available as low-power models for benchtop instruments and lab measurements, as well as medium- and high-power versions for testing transmitters, RF amplifiers and continuous-wave (CW) or pulsed transmission systems.

Waveguide terminations

Waveguide terminations are loads designed to absorb the signal inside a waveguide section, providing a low-reflection termination over the specific operating band (for example the different WR bands). They are used at higher microwave and mmWave frequencies to:

• terminate waveguide ports on antennas, front-end modules and passive components;
• create dummy loads for power testing in waveguide systems;
• reduce reflections and standing waves in high-frequency measurement setups;
• close unused line sections in radar systems and point-to-point links.

Waveguide terminations are classified by waveguide band (e.g. WRxx), dissipated power rating and maximum reflection level, typically specified as return loss in dB or VSWR.

Essential devices for RF chain stability

Using the proper terminations is crucial to keep the RF chain stable, minimise reflections toward upstream stages and protect expensive devices such as power amplifiers, test instruments and microwave front-ends. Appropriate dummy loads allow endurance tests, calibrations and power measurements to be carried out under repeatable conditions, reducing the risk of overloads and mismatches.

How to choose the right RF termination

The choice of an RF termination or dummy load depends on several key criteria:

• Mechanical interface: type of coaxial connector (SMA, N, 2.92 mm, BNC, etc.) or waveguide standard (WRxx) required by the system.
• Nominal impedance: typically 50 Ω for most RF/microwave applications, or 75 Ω for specific broadcast systems and dedicated measurements.
• Frequency band: maximum operating frequency, specified return loss and VSWR over the band of interest.
• Power handling: continuous (CW) and peak power the load can safely dissipate, taking into account duty cycle and environmental conditions.
• Application scenario: use in laboratory, production, field testing, radar or telecom and high-power systems.

If you are unsure about the required power rating, frequency band or interface type, our technical support can help you identify the most suitable termination for your RF architecture.

Overview of the main types of RF terminations

Why choose RF-Microwave RF terminations and dummy loads

• Wide range of coaxial and waveguide terminations for 50 Ω and 75 Ω systems.
• Professional solutions for microwave and mmWave, from lab setups to high-power systems.
• Clear specifications for frequency band, power rating and return loss to support informed selection.
• Dedicated technical support to identify the most suitable dummy load for your test setup.

FAQ – RF terminations and dummy loads

Why is it important to terminate an unused RF port?
An unterminated RF port can generate reflections and standing waves that affect measurements, degrade matching and, in some cases, damage amplifiers or sensitive output stages.

What is the difference between a coaxial termination and a waveguide termination?
A coaxial termination is installed on RF connectors (SMA, N, etc.) and typically covers RF and microwave bands up to tens of GHz. A waveguide termination operates on a specific waveguide band (WRxx) and is designed for higher microwave and mmWave frequencies.

How do I choose the nominal power rating of a termination?
You must consider the maximum system power, the signal duty cycle (CW or pulsed) and safety margins. When in doubt, it is advisable to select a model with a nominal power rating higher than the maximum expected operating power.

Can I use a 50 Ω termination in a 75 Ω system?
Using a termination with an impedance different from the system impedance introduces mismatch and reflections. For correct performance and reliable measurements, it is recommended to use dummy loads with the same nominal impedance as the line (50 Ω or 75 Ω).

Do you have doubts about the most suitable RF termination or dummy load?
Contact us and our team will help you select the coaxial or waveguide termination best suited to your system and test setup.