NOAA weather satellite reception

Recently I got an interest to experiment with NOAA weather satellite reception techniques. As a first thing, I did search on the internet for a suitable antenna for NOAA satellite frequencies (137.100 MHz - 137.9125 MHz). After examining a couple of designs, I decided to build a Turnstile antenna which is designed by Ivo Brugnera I6IBE.

Due to the COVID19 lock-down, I build this antenna using parts that are already available in my inventory. Originally, I build this antenna on a wood-stick, and later I changed it to a stable setup as shown below.

Assembled antenna for 137 MHz NOAA weather satellite receptions.

Following materials and components are used for the above construction:

- Two 8cm × 8cm × 6cm waterproof ABS project box.
- 54cm long, ⌀ 21mm PVC tube, which is reinforced by inserting water resistivity wood stick.
- 8mm thread roads.
- M8 nuts and M8 flat washers.
- 50Ω and 75Ω coaxial cables.
- PL259 male and female connectors.

Before constructing this antenna, I did some minor adjustments to the design by changing element spacings and lengths. The modified design is transferred to CAD drawing and available to download at the locations given at the end of this post.

CAD drawing of the antenna.

The antenna is installed 13m above the ground, which is nearly 48m from the sea level.

Wiring layout from dipole elements to PL259 connector.

RTL R820T2 SDR is used to test the constructed antenna. To get the APT transmissions I setup SDRSharp with following parameters:

Sample rate: 2.56MSPS
Sampling mode: Quadrature Sampling
RF Gain: Maximum level
Mode: Wideband FM (WFM)
Bandwidth: 40 kHz (40,000 Hz)
AF Gain: Maximum level

I examine a couple of APT decoders with my setup which including WXtoImg, APTDecoder, and noaa-apt. After examining and comparing the features provided by the above packages I decided to stick with WXtoImg to process my APT streams.

This image is captured from NOAA 18 and processed with noaa-apt. Channel A is a visible image. Channel B is the thermal infrared view.

At the testing stages, I manage to receive APT transmissions from all the active NOAA satellites such as NOAA 15, NOAA 18, and NOAA 19. I test this antenna with all the NOAA passes, and every time I manage to get an excellent signal from the satellite. Some of the satellite images which I processed with this setup are illustrated below:

Sri Lanka, India, and the Arabian sea. Captured from NOAA 15 on 25th April 2020 at 19:45:16 IST. Frequency: 137.620 MHz. MCIR false color enhancement with normal projection.


Sri Lanka, the Bay of Bengal, and Andaman sea. Captured from NOAA 18 on 26th April 2020 at 08:35:18 IST. Frequency: 137.9125 MHz. MCIR false color enhancement with normal projection.


India, Oman, Gulf of Oman, and Arabian sea. Captured from NOAA 19 on 26th April 2020 at 06:52:26 IST. Frequency: 137.10 MHz. MCIR false color enhancement with normal projection.

Composite view of NOAA 19 and NOAA 15 images. NOAA 15 pass starts at 26 Apr 2020 06:39:13 IST and NOAA 19 pass start at 06:52:26 IST.

I did CAD drawing for this antenna using FreeCAD, and it’s available to download here. The PDF technical drawing is also available here. The original design document of this antenna which is published by Ivo Brugnera I6IBE is available on his homepage.

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