====== External Antenna on the ESP32-C5 ======

We also ordered the ESP32-C5 with a u.FL connector, so we can use it with an external antenna:
{{ ::jlcpcb_externe_antenne.png?600 |}}

{{ ::esp32-c5-ufl.png?600 |}}

The schematics of the board can be viewed here:

[[https://kicanvas.org/?repo=https%3A%2F%2Fcodeberg.org%2Fopentrafficmap%2Fits-g5-receiver|KiCanvas: Display the circuit diagrams of ITS-G5-Receiver (live from Codeberg.org)]]

===== Polarization =====
On our antenna, made by Ubiquiti, horizontal and vertical polarization can be connected separately:
{{ ::pxl_20260628_180745600.jpg?600 |}}

We use a Ubiquiti airMAX 16 dBi here. There are certainly antennas that are better suited, though.

It turned out that the antenna performs significantly better with vertical polarization.


===== Measurements =====
We have a test setup with the integrated antenna of the ESP32-C5 (top) and two receivers for vertical and horizontal polarization.

{{ ::pxl_20260628_180740889.jpg?600 |}}
{{ ::pxl_20260628_180756944.jpg?600 |}}

On the heatmap we can see that
  - the vertical antenna performs best
  - the PCB antenna of the ESP32-C5 is actually also very good
  - the horizontal antenna performs worst

==== Ubiquiti vertical ====
{{ ::node99.png?600 |}}


==== ESP32-C5 PCB antenna ====
{{ ::node98.png?600 |}}

==== Ubiquiti horizontal ====
{{ ::node101.png?600 |}}