In this article, we’re diving into the use of RF dummy loads for VTX (video transmitter), radio transmitters, and Triple Feed Patch antennas. These devices are self termination circuit with a 50-ohm impedance and an SMA/RP-SMA connector, which are used for dissipating RF energy. Known as “RF terminations,” they play a crucial role in safeguarding your equipment.

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Where to Buy?

RF dummy loads can be purchased from various vendors, including:

• AliExpress: https://s.click.aliexpress.com/e/_DE3Ya3x
• Amazon (affiliate link): https://amzn.to/3wbc1qs

For Radio and Video Transmitters

Removing antennas from your FPV drone and radio makes it easier to pack for travelling. However, powering them up without reattaching the antennas can lead to significant problems.

Further Reading: TX16S Removable Antenna Mod

When antennas are absent, the power from the transmitter reflects back into its output circuitry, potentially causing rapid heat build-up and damage, particularly to the output transistor. Some radio transmitters may offer internal protection and warnings if an antenna is missing, but it’s always better to err on the side of caution.

Image credit: SnowLeopardFPV (https://intofpv.com/t-homer-simpson-moment)

RF terminations, or dummy loads, are excellent for protecting transmitters when you choose to remove the antenna, whether it’s a 5.8GHz VTX or a 2.4GHz/900MHz RC transmitter. These small and cost-effective gadget not only protect your equipment if you forget to reattach antennas but also keep the SMA connector free from dust and debris.

Interestingly, dummy loads can be useful for changing VTX channels in the field. Since they emit significantly less signal than a proper antenna, they minimize interference with other pilots.

For Triple Feed Patch Antennas

Dummy loads are particularly useful for Triple Feed Patch antennas (product page: https://s.click.aliexpress.com/e/_DdxtiWD). These antennas come with two outputs, RHCP and LHCP, but typically, only one output is used at a time. It allows you to switch between these polarizations any time you want. Attaching a dummy load to the unused output prevents signal leakage, thereby enhancing the antenna’s performance and efficiency.

Triple Feed Patch Antenna with Dummy Load on One Output

Check Before Use

Before using a dummy load, it’s advisable to test with a multimeter . Measure the impedance between the middle pin and the outside. A properly functioning dummy load should show a reading around 50 ohms. This simple check ensures your equipment functions optimally.

Conclusion

Incorporating RF dummy loads is beneficial for protecting VTX, radio transmitters, and optimizing certain type of antennas, offering a simple yet effective solution to enhance your FPV equipment’s longevity and efficiency.

Edit History

• Jun 2021 – Article created
• Dec 2023 – Updated