Does Size Still Matter? Exploring Antenna Size

September 25th, 2015

By simply understanding the basics of antenna size, you can make better-informed choices when shopping for a two-way radio system, whether it’s a handheld unit, a mobile radio for your vehicle or a two-way radio base station.

The most important aspect of a radio antenna is that it is properly matched to your radio and the frequency band you’re operating on. The higher the wavelength, the longer the antenna needs to be to match it properly, and the wavelength is inversely proportional to the frequency. UHF frequencies have a shorter wavelength and therefore, the antenna can be shorter than for an equivalent VHF radio. A poorly matched antenna is a common cause of reduced range. So the answer is yes, size does matter, but bigger isn’t always better. It all depends on what your transmitting and receiving frequencies are.

Theoretically, a longer antenna will have a greater range, but it is far more important for optimal radio performance that the length of the antenna matches the frequency. With a handheld two-way radio, in many cases it is not even possible to remove the antenna. In fact, in some models, the antenna has been purposely embedded inside the radio, to make the unit more compact. Occasionally there are handheld radios that have removable antennas. If your radio can use different sized antennas, typically this is done so that you can switch out a whip antenna (which will give you wider coverage) with a stubby antenna, which will make the radio more compact. Obviously, using an external antenna with a handheld radio that you’re moving around with is not possible. If you’re using a stubby antenna, you might be able to switch to a longer antenna, but remember that it has to be correctly matched. The antenna that originally came with your handheld two-way has been specially “tuned” for that model and its frequencies.

More important than the length of the radio antenna is the height of the antenna. No, that isn’t the same thing. By height, we mean how far above the earth’s surface it is. The higher you can place the antenna, the further the range that you can successfully transmit and receive.

With a mobile radio that’s inside a vehicle, an external antenna becomes necessary because radio waves will be stymied by the metal of the vehicle. In this case, an externally-mounted antenna will give you better range. But again, the size of the antenna must be properly matched for the frequency you’re transmitting on.

It is also possible to extend the range of a handheld device with an antenna if it is part of a desktop base station. A base station radio might have a built-in antenna, but it can be disconnected and instead be connected by cable to an external antenna. The higher you’re able to mount the external antenna, the better the range will be. Mobile radios and base station radios are far more powerful than handheld radios, sometimes as high as 100 watts.

Keep in mind that with certain frequency bands, there may be limits to how high an external antenna can be. For MURS radios, the FCC dictates that the antenna height cannot be greater than 20 feet above a structure or 60 feet above ground level, whichever is greater.

In general, for achieving greater range with any type of two-way radio, you can raise the height of the antenna or increase the radio’s power. If possible, do both.

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