How to Use UHF Wireless Audio On Set

January 29, 2024

Deity Theos. Why uhf?

Now that you know…

In our last article, we tackled how UHF works and what makes it so much more powerful than 2.4GHz.

But that’s only half of the conversation.

…Now what?

You bought your shiny new kit, you show up on the day… but now what?

Today we teach you how to use UHF digital wireless on a professional film set.

But, now what?
Noir film set. two actors laved with Deity Theos

The project

Today’s shoot is a film noir in an old Hollywood house.

  • You’ve received your morning sides from the AD.
  • You know how many people are on camera.
  • You know how many wires need to be set up.

The challenge

There are two actors, and the location is tight!

This means we’ll need 2 lavs and our sound mixer will have to set up in the next room over and record through the concrete wall.

Noir film set top down image
Scanning with Deity Theos

First, scan.

Now that we understand the situation, we can talk about the first step of using UHF – scanning.

How many frequencies?

At the top of the day, we conduct a scan of all the nearby frequencies to find the cleanest ones for our devices to use.

We’ve been told we need two transmitters so that’s at least two clean frequencies.

RF scanner showing nearby frequencies
Deity D2RX conducting scan

What do I use for RF scanning?

You can use a dedicated RF scanner or the one included in your wireless system.

If you’re using the Deity THEOS you can conduct a scan right from the D2RX receiver which means one less piece of gear you need.

Know your laws

Before you get to set, you should familiarize yourself with local laws and regulations for UHF transmission as they differ greatly from place to place.

Then conduct your scan accordingly.

Deity frequencies page.
Example RF scan

Example RF scan

Let’s look at this scan of our set. Ideally, our devices should use the frequencies in green to the right, where the RF noise is lowest. The red “noisy” bands have a lot of spikes which equal interference.

Take note of the good frequencies and then enter them into your transmitter and receiver.

Skip the manual settings

If you’re using THEOS, as long as your transmitters have been paired to your receiver, your system will automatically select them for you after your scan.

Deity D2RX auto assigning frequencies
Two Deity DBTX that are 700KHz apart

700kHz is the magic number

If you have to manually select frequencies, you need to be mindful of properly spacing them.  Make sure your transmitters are all at least 700kHz apart.

They need to be at least this far apart to avoid intermodulation – or self-generated interference.

Skip even more manual settings

Again if you use the built-in scanner in the Sidus Audio app, it will find and assign these spaced-out frequencies to your devices automatically.

Sidus audio app auto assigning frewquencies
Deity Theos menu showing frequency blocks

Frequency blocks

Say after you’ve scanned a frequency block, you don’t see any available space for your devices.

You could of course ball up and cry because your job is over…or you can just check another frequency block.

The Deity THEOS gives you access to all the frequency blocks legal in your area, so scan each one to find the best block for you. Make sure to change antennas accordingly.


Once you’ve found the right frequencies, it’s time to lav up your talent and hide the transmitters.

Much like everything in the sound world – it’s not always as straightforward as it sounds.

Laving with Deity Theos
Deity Theos transmitting through concrete and brick

Nearby materials

You can hide UHF transmitters anywhere on talent generally, you just need to be mindful of one major thing – what material – and how much of it – is between the transmitter and the receiver.

Avoid transmitting through people

UHF radio waves are tremendously robust and can punch through most materials, though it’s best to try and avoid as much as possible.

You should mount the transmitter on a part of their body with the least amount of mass on ‘em. Like an ankle, versus a waistband.

Example of transmitting audio signals through people using Deity theos
UHF butterfly antenna

What is LOS?

Even more ideally, in a position that’s directly facing your receiver.

We often use the term “line of sight” or “LOS” to refer to this – nothing between TX and RX.

The right tools

Ankle straps or other specialized mounts can be your best friend in achieving this.

Make sure to have a fully stocked expendables kit before you head to set.

Production sound mixer attaching Deity Theos DBTX to actress ankle
rusty rebar in wall blocking UHF audio signals

The location could be a problem

Another thing to be mindful of is the material IN the walls of your set.

There can be problematic piping, wiring, rebar, or any number of dense things. Try to work around these if you can.

Work around the set

One of the best ways to deal with this is by “remoting” your receiver’s antenna.

Remoting antennas with Deity Theos
Top down of film set showing remote antenna for UHF

Our setup

So in our setup, we need to receive the signals from our two actors through this concrete wall full of piping.

Using an extended coaxial cable we rigged up an external antenna on the inside of the room. This way we don’t have to transmit through the wall to get a good recording.

The transmission takes place all in the same room, and then the signal gets to us via hardwire – much more reliable.

Remoting is a common solution, use it

You’ll see a lot of sound mixers using remote antennas in stadiums, concert halls, or other metal structures to help combat material problems.

UHF butterfly antenna
How RF power for UHF works

Increase the RF power

If you’re on set and are forced to transmit through conductive materials for whatever reason, you can still increase the RF power to strengthen the punch of your signal and hopefully get through those problematic materials.

Be sure to check your local RF power laws.

Transmission tools

We touched on antennas a little bit already but there are a couple more key things to know to properly use them.

UHF antenna types

Antenna types

For filmmaking, there are generally three you need to be aware of.

Whips, Shark fins, and dipoles.


Whips are the most common antenna you’ll find. It’s a simple wire that captures a very narrow amount of frequencies at a limited range.

The length of the antenna dictates which frequencies it can send and receive.

Deity Theos UHF whip antennas
cutting Deity theos antennas

Cut to length

Though they only capture a small window of frequencies you can cut whips to the exact length you need, keeping them cost-effective and versatile.

External antennas

If you need to transmit across long distances or have to place a remote antenna for reasons we discussed earlier, you will need to use an external antenna.

These often require a coaxial cable to use rather than plugging directly into your receiver like a whip.

UHF butterfly antenna
How sharkfin antennas work with the Deity theos


The shark fin antenna is directional and used for picking up signals really far away.

It can also be used to avoid picking up interfering signals coming from the sides of the antenna.

Dipoles / Butterfly variant

A dipole and its variant, a butterfly antenna, are omnidirectional and great for when transmitters are moving everywhere on set.

How butterfly antennas work with the Deity Theos
Types of UHF antennas and their frequency ranges

Frequency ranges

Of these three antennas, a shark fin and butterfly antenna will span an ultra-wide bandwidth of frequencies, while a dipole is more narrow.

Antenna Distros

Lastly, if you need to distribute an external antenna to multiple receivers, you should add an RF antenna distro to your kit.

An RF distro comes in many forms, but they all allow you to use one antenna for your receivers in place of many, keeping your setup light.

Antenna distribution using Deity D2RX receivers
Advice for using UHF on set

Bottom line

If you want to be a professional sound mixer, always carry a variety of expendables and antennas, and study your location ahead of time for potential problems.

Do your homework!

Get Recording

Hopefully, this article has helped you become a more confident sound mixer!

Be sure to check out the rest of our blog which is packed with other sound advice. Happy shooting!

Sound mixer giving a thumbs up on set