Is an FM Radio Transmitter Causing Interference Issues?

By Greg Martinez / August 25, 2020
fm radio transmitter

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Causes of interference, coming from both within our home and without, can be myriad, and can put the damper on our enthusiasm for a relaxing evening in front of the television.

But rather than merely getting frustrated at the situation and deciding to do something else, it’s important to understand what’s causing the interference.

In fact, I’d say knowledge is truly power in such cases—and may allow us to find a fix and get back that crystal clear picture and audio we so desperately want.

In this article I talk about one particular factor called “FM radio transmitter interference.” It’s a kind of radio frequency interference that’s been around since the dawn of wireless communication.

What Is Radio Frequency Interference?

First of all let me say that radio frequency interference isn’t just something that affects us cord cutters and TV antenna users. It can be a pain for practically all applications that depend on radio wave propagation, from audio devices to cell phones:

Radio frequency interference commonly occurs when two or more radio waves (frequencies) meet and “compete” with one another. It’s the presence of unwanted signals within a given frequency that’s being used by the devices experiencing the interference.

Let me explain that a bit more:

Electromagnetic radiation is in pretty much everything we use from visible light to the workings of a child’s walkie-talkie. As an advanced civilization we’ve learned to exploit a certain small portion of the entire spectrum in our wireless communication technology.

The spectrum for wireless communication—3 kiloHertz (kHz) to 300 GigaHertz (GHz)—seems quite large but the usable portion for the civilian sector is of course much smaller than that:

  • Cellphones tend to broadcast and communicate at 850 MHz
  • Wireless home phones at 900 MHz
  • FM radios from 87.5 MHz to 108 MHz
  • Your wireless router and other Bluetooth devices transmit at 2.4 GHz

To impose order and reduce competition (and thus minimize radio frequency interference), the government limits the frequency bands on which various devices can operate.

The FCC allocates certain frequencies to radio and TV stations in a given area to reduce conflicts as well, although physics and the weather can sometimes be mischievous.

What are Common Causes of RF Interference?

Here’s a list of some of the most common causes of RF interference that occur in day-to-day life:


Sweep aside all the tech hype and fancy words associated with this technology, and you’ll uncover a little radio transmitter and receiver.

Yes Bluetooth actually works with FM radio waves, transmitted over short distances ranging up to 30 feet.

Bluetooth is ubiquitous and embedded in countless devices from cellphones to speakers, watches, health monitors, tablets, and more. It also transmits on the 2.4 GHz band.

Bluetooth radio waves essentially hop over 802.11 transmissions and sometimes bump or interfere with others using this band.

This is especially true when you’re dealing with an older 2.4 GHz 802.11b network. This may explain why your Bluetooth device is causing interference as it both establishes connectivity and communicates with other compatible devices.

WiFi Network

WiFi networks also use the 2.4 GHz band, which in turn, is divided into a number of channels with only three of those not overlapping. Whenever more than one WiFi network transmits on the same channel, you’ll get what’s called “co-channel interference.”

Whenever more than one WiFi network transmits on adjacent networks, then this is referred to as, “adjacent-channel interference.” None of this interference entails good times for users, but can be avoided by using an RF interference scanner.

Cordless Phones

Although no longer as popular, there are still many homes that use cordless phones.

These devices use the 900 MHz or the 2.4 GHz and 5 GHz bands. The most common type nowadays are cordless phones that use the 2.4 GHz band.

However, since such phones are quickly becoming obsolete, it’s less likely you’ll experience this kind of interference going forward.

Microwave Ovens

While not all of these can create problems, most microwave ovens can emit interfering signals that take up the whole 2.4 GHz band.

The good news, however, is that even if your microwave causes such interference, it only does so when in use, so you should be OK most of the time. (Just don’t put the microwave next to your WiFi router.)

Other devices that may similarly generate or experience FM radio interference include:

  • Baby monitors
  • Video cameras
  • Outside electrical power lines
  • Equipment operated by direct satellite providers

How to Minimize Radio Frequency Interference

The thing about radio frequency interference is that it can be unpredictable: for the most part, it may just be an irritating bzzzt-baba-bzzt sound coming through one of your devices.

It can, however, escalate, especially when dealing with things like pacemakers that can affect someone’s quality of life (even for the worse).

While most of us worry about some FM radio transmitter (whether inside or outside the home) ruining our TV or phone reception, it pays to remember that such interference may (rarely) have more serious consequences.

That’s why we should try to minimize radio frequency interference in our environment. Here are some helpful tips:

Radio Frequency (RF) Field Meter or Reader

If FM radio transmitter interference is a real problem around your house, it may be worthwhile to confirm the sources by using a Radio Frequency Field Meter.

Yes I know this is a rather serious answer to interference, but may help you diagnose and find solutions to issues:

Radio Frequency (RF) Field Meter

These devices are simple enough to get and use. Depending on the model you go for, they can detect most types of electromagnetic frequency pollution, including:

  • Radio frequency interference
  • AC magnetic interference
  • Electric fields

Buy RF Shielding Material

RF Shielded Nickel-Copper Fabric

Depending on the kind of RF interference you’re experiencing, and how serious you are about solving that problem, there are RF shielding materials you can buy today.

One of the most common and popular options is the RF Shielded Nickel-Copper Fabric. This is specifically designed for people who want to shield their homes from RF radiation and interference.

The fabric is flexible enough to be used as drapes or even wall coverings. If that doesn’t work for you, then you could go for a more localized solution:

Final Thoughts

Apart from buying these shielding or filtering devices, you may decide to get to the root of the problem by:

  • Buying good quality equipment: For the most part, high-quality products are designed to solve most of the modern problems we have. Some companies work very hard to try and incorporate RF shielding within their designs, and this, in turn, reduces the level of interference emanating from these devices.
  • Adhering to proper installation protocol: The truth is that most of us don’t both to read the instruction manual, just as we don’t bother to read the terms and conditions on most forms we sign. While it’s true that most devices are designed to be easy to install and use, it’s sometimes in the smallest of mistakes that we create the biggest problems. These installation mistakes might not stop the device from working, but it might affect how efficiently it does so. By eliminating installation mistakes, you can also minimize the level of RF interference.

Then of course, there are other preventable, minor offenses, such as avoiding:

  • Putting your microwave next to your WiFi router
  • Charging your phone next to your FM radio transmitter
  • Generally putting two devices that could interfere with one another near each other

While it’s true that your FM radio transmitter could be causing interference, you don’t have to get rid of it entirely.

You need to figure out how to ensure the device plays well with others. The tips given here will help reduce the level of interference from your FM radio transmitter and any other device that could cause this kind of interference.