Understanding RF Multipath

Quick Read Summary: A new training video from CRFS to help users of ‘Radio Direction Finding’ (DF) Arrays understand the importance of multipath. The video animation is designed to help users visualize real-world environments in terms of multipath/RF reflections. Different object models are used alongside materials that reflect RF differently to demonstrate the principle.


RF Training

A slightly different blog post here, sharing a piece of training material we put together to help explain the effect of ‘RF multipath’ in the real world. It’s not designed to be a perfect model, but simply to show how different surfaces reflect RF back from both a moving point of origin and a moving point of view. We look specifically at Angle of Arrival (AoA) Geolocation as it’s a common method that’s easy to explain. The CG environment used here was selected because it demonstrates multiple surface angles, complex objects (pagodas) and jagged bare rock alongside a variety of different organic surfaces.

daylight aircraft radar

We wanted to show how the world we interact with every day would look through an RF sensitive eye. Hopefully, doing this means users of any RF sensing equipment will be able to visualize the world around them, without the need to understand the specific science around why.

For this example, we have assumed a world without background noise to focus on the signals we are looking at: a fighter jet and ground-based rotating radar located above a pagoda.

aircraft with radar

Once oriented into a world where vision is defined by RF, we pull the story back to how a Direction Finding (DF) system sees that same world. Here we see 3 faces of a radio direction finding array. The array would in reality have more directional surfaces (in our case 6), which give a 360-degree view of the world around them. This view was chosen to represent the view you would have looking from the center of the array through to the outside world.

radio direction finding array mix


Check out the real thing on our RFeye Array page. These ultra-sensitive radio direction finding arrays are used by our customers to locate a multitude of signal sources from drones and drone controllers through to radars, and can even be found protecting the most valuable cargoes on their way to outer space.

In the final scene, we look at atmospheric effects and millimeter wave signals in heavy rain as a reminder that most RF signals in use around us are not affected in the same way as light. Even in dense fog, most radio signals remain true.

atmospheric annotated

The intention is to continue the series, looking at other RF methodologies through the magic of the RF eye. Do get in contact if you would like to see something specific in the future.

Watch the full "Understanding Multipath RF for Direction Finding" animation here.

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