How to Download RADAR Image using Google Earth Engine

 RADAR stands for 'RAdio Detection And Ranging'. It is a system that uses radio waves to determine the distance (ranging), direction (azimuth and elevation angles), and radial velocity of objects relative to the site. Radar remote sensing is a type of active remote Sensing which uses electromagnetic energy backscattered from ground targets to extract physical and dielectric behavior.

A free common source of RADAR image is the Sentinel-1 satellite that uses the C-band SAR (Synthetic Aperture Radar) sensor to acquire Radar imaging.

So, in this post I will guide to on how to download Sentinel-1 image (which is a Radar image) using JavaScript code in Google Earth Engine. Lets get our hands dirty!

To download a RADAR (SAR) image using Google Earth Engine (GEE), you must filter a SAR collection—typically Sentinel-1 Ground Range Detected (GRD)—create a single-image composite, and export it directly to your Google Drive.

Here is the complete workflow and JavaScript code to achieve this.

Step 1: Write the GEE Script

Open the Google Earth Engine Code Editor and paste the following script into the central console:

// 1. Define your Area of Interest (AOI)
// You can also draw a polygon manually using the map geometry tools
var aoi = ee.Geometry.Rectangle([8.05, 8.25, 8.55, 7.50]); // Example: Okokolo, Benue state, Nigeria
Map.centerObject(aoi, 12);

// 2. Load the Sentinel-1 RADAR (SAR) Image Collection
var SAR_collection = ee.ImageCollection('COPERNICUS/S1_GRD')
  .filterBounds(aoi)
  .filterDate('2026-01-01', '2026-06-30') // Filter by date
  // Filter for Interferometric Wide (IW) swath mode
  .filter(ee.Filter.eq('instrumentMode', 'IW')) 
  // Filter for dual-polarization (VV and VH)
  .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VV'))
  .filter(ee.Filter.listContains('transmitterReceiverPolarisation', 'VH'));

// 3. Create a single median composite image and clip it to your AOI
var raw_image = SAR_collection.median().clip(aoi);

// 4. Select the desired RADAR bands (VV, VH, or an added ratio)
var download_image = raw_image.select(['VV', 'VH']);

// 5. Add the processed image to the map view for a visual check
Map.addLayer(download_image, {min: -25, max: 0}, 'Filtered SAR Image');

// 6. Set up the export command to Google Drive
Export.image.toDrive({
  image: download_image,
  description: 'Sentinel1_RADAR_Download',
  folder: 'GEE_Downloads', // Subfolder name in your Google Drive
  scale: 10,               // Spatial resolution of Sentinel-1 is 10 meters
  region: aoi,             // Target boundary
  fileFormat: 'GeoTIFF',
  maxPixels: 1e13
});

Step 2: Execute the Script

1. Click the Run button at the top of the Code Editor.
2. Look at the right-hand panel and click on the Tasks tab. You will see your export task (Sentinel1_RADAR_Download) highlighted in orange/yellow.

Step 3: Run the Task & Download From Google Drive

1. Click the Run button next to the task name in the Tasks tab.
2. A pop-up configuration window will appear. Confirm the parameters (leave them at defaults) and click Run again.
3. The spinning gear icon indicates the processing stage. This can take anywhere from a few minutes to an hour depending on the size of your AOI.
4. Once the icon turns into a blue checkmark, open your Google Drive.
5. Navigate to the GEE_Downloads folder and download the GeoTIFF file directly to your computer. You can now import and analyze the raw RADAR image inside external desktop GIS software like QGIS or ArcGIS.

RADAR (SAR) imagery is uniquely powerful because it uses microwave signals. Unlike optical satellites (like Landsat or Sentinel-2), SAR penetrates clouds, smoke, and darkness, allowing it to capture data 24/7 in any weather conditions. SAR sensors do not capture colors; instead, they measure surface roughness, structure, moisture content, and dielectric properties.

Happy mapping!