LPFM Radio Stations can be started with fairly basic and low cost equipment. There are however five things you must have to begin your broadcast.
These are the basic items you need to start a radio station. But what will you broadcast? You still need some sort of studio.. Now the spending starts.. But don’t worry, we have put together several packages to fit just about any budget.
The LPFM Store has helped start up a number of FM radio stations in the United States and abroad as well as helping start up many LPFM radio stations in the U.S. We provide radio consultancy services for hundreds of customers. Our services include advising on radio installations, from licensing to full power and low power radio stations.
There are several ways to start up an FM radio station or LPFM radio station in the United States. The lowest cost licensed method is a low power FM license. The second method is a full power FM License or Non Commercial Educational License (NCE.) In this article we look at information geared towards LPFM radio. Much of the information is appicable to full power fm radio stations as well.
INFORMATION FOR THE FIRST TIME BROADCASTER
Some things you’ll need for the studio would include a good audio mixing console, one or more microphones, CD players, automation computer and software, production computer with audio editing software, maybe a cassette deck, studio monitor amplifier, speakers and of course headphones.
What’s a Watt about
Every LPFM station has a maximum ERP (Effective Radiated Power) of 100 watts based upon 30 meters above average terrain. The “ERP” is determined by the type of antenna, height, type of cable and power output of the transmitter – this might be between 10 watts and 250 watts.
Is the Antenna Really Important?
Yes – Yes and Yes! The antenna is your final link in your RF system. This couples the energy developed by the transmitter and delivered by your coax to the “air”. The more efficiently the antenna can couple the energy to the ether – the better your station will sound. Of course too much efficiency can get you into trouble by exceeding the maximum “ERP”, so be careful when deciding on your antenna. You can’t get too much efficiency, but adjustments of the transmitter’s output power would need to be adjusted.
The Basic Dipole
Otherwise known as a vertically polarized antenna with roughly a 1:1 ratio, which means one watt in equals one watt out. If your station is operating in an area where you need to “reach out” to the horizon, this antenna may make sense. It is an excellent car reception transmitting antenna, but can be susceptible to a phenomenon known as “picket fencing” More on that later
Circular Polarized Antennas (CP)
These use both the vertical and the horizontal. In a true “CP” single antenna of this design requires about twice the Power compared to a dipole. This is due to the gain ratio being less than one half. This antenna does not reach the horizon as well, but does concentrate its power on building penetration and close in stronger field strength. You can recover the horizon by adding more than one antenna. This also increases the overall gain of the system allowing you to operate with a smaller transmitter.
Full Wave Spaced Antenna
Adding multiple antennas spaced properly will increase your gain. A two pay system in a “CP” design would require about half the TPO or Transmitter Power Output of a single bay “CP”. And as previously mention it will send the signal toward the horizon more than a single “CP” antenna.
Half Wave Spaced Antenna
These are spaced approximately half that of a full wave system. Antenna Doing so will decrease the overall gain of the system about half. Therefore you would need to double power transmitter. Why in the world would you want to do this? On the surface it sounds like you would just be generating a larger power bill. But the resulting beam from the half wave system will be more narrow with very little or no radiation above and below the antennas, instead you will have a tight signal heading off toward the horizon. This is perfect if you are in an area with flat land (Florida anyone?) and distant transmission.
The Cable – It’s just wire
Don’t fall for the myth that any cable will do the job. Your coaxial cable is a very important link in the RF chain. Cheap cable can eat up your transmitter power, meaning less power gets to the antenna. If less gets to the antenna, less is radiated. There are many types of cable out there, choosing the wrong cable can really cause serious problems with your station. Be sure to use a qualified broadcast Engineer to determine the proper type of cable. Many factors influence this including, power output of transmitter, length of cable, etc. Suffice it to say that most installations of an LPFM station need at a minimum ½ inch Andrew heliax or LMR 600 from Times Microwave.
Who needs Processing? It’s just a 100 watt station.
The best thing about radio is the average Joe Public doesn’t even begin to know the meaning of a watt. If they can hear you and they like what you are playing, they listen. But you can SOUND like those big stations, wattage has nothing to do with it. Good audio processing can make you sound as loud and strong as the flame thrower down the street. So it’s important to spend as much as you can on a good audio processor. We suggest the Inovonics OmegaFM or the Omnia 6. Then you have the lower cost alternatives Inovonics, DAVID III. This is a quality audio processor that can give you that loud punch to be competitive with the other stations.
EAS / CAP– Who needs it
You do and it’s the law! FCC rules require LPFM’s to only have a Decoder. These units allow interruption of your broadcast for national emergencies, inclement weather and even Amber alerts or children abduction notices. We have several systems available. Each unit will have two radios which monitor other radio stations or NOAA for distributed alerts. It is very important to have and maintain your EAS /CAP system.