How to Choose a Two-Way Radio

Two-way radios are essentially available in three types: hand-held portable, vehicle-mounted mobile, and desktop base station. There are also unique two-way radio devices such as indoor and outdoor call boxes and one-way radio receivers for wireless paging as well.

Handheld portable two-way radios are the walkie talkie type of radios you see people carrying around. As ruled by the FCC (Federal Communications Commission), handheld radios may not have more than 5 watts of power.

Vehicle-mounted mobile two-way radios mount in a car or truck and they use the vehicle's battery for power. They may have their own antenna, but better range is achieved by using an externally-mounted antenna.

Desktop base station radios use wall AC power and they too may have a built-in antenna, but this antenna may be disconnected and then connected to cable that leads to an external-mounted antenna. The higher the antenna is mounted, the better the range. The vehicle-mounted mobile radios are usually used as base stations by just adding an AC to DC power converter.

Mobile and Base station radios are usually more powerful than hand-held radios and may have as much as 100 watts of power.

UHF or VHF

There are two major formats for two-way radios. They are Ultra High Frequency (UHF) radio and Very High Frequency (VHF) radio. Neither frequency band is inherently better than the other. They each have their pluses and minuses. Both formats are effective ways to communicate with another person so deciding on the right radio for you depends on your application.

Lower frequencies or wavelengths have greater penetrating power. That's one of the reasons they are used for communicating with submarines. VLF radio waves (3-30 kHz) can penetrate sea water to a depth of approximately 20 meters. So a submarine at shallow depth can use these frequencies.

So from what you read above you may think VHF is always the better choice for a two-way radio no matter where you are using it. That's not necessarily true. Even though VHF has better penetrating capabilities, that doesn't necessarily make it the better choice for buildings. The wavelength of a wireless frequency has a big impact on transmission.

To explain this let's assume we are communicating from one side of a commercial building to the other. In between these two points is a metal wall with a three foot door in it. Metal is an enemy to radio waves and they typically don't pass through it.

For our example let's assume that the UHF wavelength the radio uses is about a foot and a half long and a similar VHF radio is around five feet long. These are in the ballpark of their normal wavelengths.

When the UHF transmits its signal the foot and a half long wave will pass through the door since the door is wider than the wavelength. The VHF signal will be totally reflected since it is wider than the opening to the door.

Your microwave oven is an example of this. The glass front door has a metal mesh with very small holes. Microwaves being a very high frequency have wavelengths that are only several inches long. The mesh keeps the microwaves trapped in the oven but it allows you to see inside because light waves have a microscopic wavelength.

Just imagine walking through the building carrying a five foot wide pole. You will encounter the same challenges a VHF signal encounters. Now imagine walking through the building with a pole that's only a foot and a half wide like a UHF wave. There are lots fewer doorways you couldn't get through.

The one difference is that wireless signals will penetrate through drywall, masonry, human bodies, furniture, wall paneling, and other solid objects. All these objects will reduce the signal strength though. The more dense the object, the more it reduces the signal. VHF will penetrate these obstacles better than UHF, but that doesn't necessarily mean that VHF is better for indoor applications.

In our example above we assumed you had a metal wall with an opening. If you reverse this and you have a three foot metal object in front of the transmitting radio, then VHF would win. Since the object is three foot wide it will totally block the UHF signal whereas the VHF signal will get around it. Lower frequencies such as VHF diffract around large smooth obstacles more easily, and they also travel more easily through brick and stone.

For most applications, lower radio frequencies are better for longer range. A broadcasting TV station illustrates this. A typical VHF station operates at about 100,000 watts and has a coverage radius range of about 60 miles. A UHF station with a 60-mile coverage radius requires transmitting at 3,000,000 watts.

So there is no clear choice for which is better, VHF or UHF. There is a lot of "black magic" to radio technology so it's not always easy to tell which will work better for your application.

The other thing you need to decide is whether you want to get an FCC license or not. If you are purchasing a radio for your business, most business-band radios require you to get a license from the FCC before you can use the radios. For business use, most VHF and all UHF frequencies require an FCC license.

One exception to this is if you purchase radios that operate in the MURS frequencies. You can buy radios in the unlicensed 151.8200 to 154.6000 MURS VHF range that don't require a license. Otherwise, the licensed 151.6250 to 154.6550 VHF Business Band and the licensed 461.0375 to 469.5625 UHF Business Band range require licensing.

To help you decide on the best radios for your application, more detail on these can be found in a book called "Two Way Radio Success: How to Choose Two-Way Radios, Commercial Intercoms, and Other Wireless Communication Devices For Your Business." Just Google the phrase "two way radio success" and you'll find it.
David Onslow is the marketing director at IntercomsOnline.com, which specializes in selling two-way radio and intercom systems for business use. Go to http://www.IntercomsOnline.com to see VHF and UHF two-way radios and intercoms.

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