Pay attention to the SiK telemetry antennas

Hardware Radios
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If you use chinese telemetry pay attention to the antennas they send you.
Many times they absolutely do not match the frequency of the SiK module.
I had 915 MHz telemetry with 2.4 GHz antennas, 433 MHz telemetry with 600 MHz antennas (???).
But even when they match, the performances are horrendous.
I created “Helical Round ‑ Wire Coils”, calibrating them with the NanoVNA V2.
The original antennas could not connect through 5 walls and a shutter, distance as the crow flies 50 meters.
With the antennas I have designed and built i’ve 88% telemetry signal.
I also open this post to discuss the various types and techniques of sizing based on the operating frequency.
Some useful links:

https://daycounter.com/Calculators/Helical-Antenna-Design-Calculator.phtml

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@marco3dr I changed topic to Radio Hardware

Agree, I most of chinese antennas are out of tune and sometimes work as a second harmonic with the obvious reduced gain and lower Q.

Working with the cheap Vector Network Analyser and using a quality 900Mhz antenna as a reference , I foud our that most of my pigtails where tuned around 1.03 Ghz :slight_smile:

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With that same analyzer, it becomes very easy to build your own simple dipoles that are tuned reasonably well. I get pretty good performance with a couple that I’ve made (not quite as fancy as those shown above).