Have you ever really thought about how radio transmission works? The answer is probably yes for anyone considering a job in radio. Understanding some of the basics of radio transmission can help you refine your skills and expertise and address technical questions about FM radio range distance and other key topics.
This handy resource guide explains the “what” and “how” of the coverage of an FM transmission system.
What Are Radio Waves?
Let’s start with the basics.
Electromagnetic waves of all frequencies surround us. Radio waves are a part of a specific range of electromagnetic waves, which include X-rays, gamma rays, UV rays, microwaves, infrared, and visible light.
Radio waves are similar to light waves in many ways, but they exist at a frequency that cannot be detected by our eyes – which is why you can’t see radio waves. Both FM (Frequency Modulation) and AM (Amplitude Modulation) programs are broadcast via radio waves.
A transmitter produces a radio wave and is picked up by a receiver. An antenna allows a radio transmitter to send energy into space and a receiver to pick up that energy. Generally, transmitters/receivers are specifically engineered to only operate across a certain range of frequencies.
The Concept of Modulation
Electricity moving through the air exists as random noise until it is modulated. Modulation is the process by which electricity can be translated into signals that communicate information (such as voice or music), and it is the foundation for FM/AM radio signals.
Without modulation, the electricity cannot be effectively changed into a useful radio transmission.
Factors that Determine the Coverage of an FM Transmission System
Now, let’s take a closer look at the factors that affect the coverage area of a given FM transmission system.
A good rule of thumb is to double the distance covered. It would help if you quadrupled the power.
Although many different factors play a part in how far an FM signal will reach, four of the most important are:
- Effective radiated power (ERP)
- Antenna height
- The shape of the surrounding terrain
- The type of area to be covered (rural, urban, and other areas.)
How to Calculate Effective Radiated Power (ERP)
Three of the four factors above are fairly easy to discern. But how do you calculate ERP? You’ll need a handful of key details and some quick math.
To calculate ERP, you must determine the following:
- The transmitter’s output power
- The losses of the coaxial cable that is being used to connect the antenna to the transmitter
- The length of the coaxial cable
- The antenna system type (circular polarization, single antenna, multiple antennae, dipole vertical polarization)
- The antenna system’s gain (positive or negative) in dB
Using these details, you can then plug the necessary information into the ERP formula:
ERP = Transmitter power in Watts x 10^((Gain of the antenna system in dBb – losses of the coaxial cable) / 10)
Other Factors to Consider
Once you figure out the ERP, there are other factors to keep in mind, including:
- The height of the antenna in comparison to the area to be covered
- The height of any trees, buildings, or other structures in the area
- The type of terrain (flat, hills, and other terrains)
- The receiver’s sensitivity level
- The proximity of other radio stations that are broadcasting at the same frequency (and whether they may block/interfere with your signal)
Want to Work in Radio & TV Broadcasting?
Before you can kick off a successful career in broadcasting, there’s a lot to learn. But with a hands-on training program that puts you in the classroom and the studio, you can gain the essential skills and experience you need to get your foot in the door.
At the Beonair Network of Media Schools, with campuses located in Miami, Chicago, Colorado, and Ohio, our Radio & TV Broadcasting program is specifically designed to help propel students toward the careers of their dreams. Here, you can learn all about the technical aspects of broadcasting while also nurturing your creative passion. Plus, we can help connect you with broadcasting internships in major cities, so you can be that much closer to the job you’ve always wanted.
Start Pursuing Your Career Goals Today!
You can turn your hobby into a fulfilling, lifelong career – you just need to take the first steps! Contact our team for more information, or apply online now!