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All About CB Antennas



Introduction

This is a self-instructional training guide designed to familiarize you with the basics of the electronic division of the truck stop business. As a salesperson, you will receive many questions concerning antennas. This guide contains some general information and common questions asked about these devices.

After reading this guide, you should be better qualified to offer information to your customers and to help them select the item that best suits their needs. We encourage you to use this guide as a tool and refer to it often.

What you should know about Antennas
Your base, mobile or portable CB transceiver requires an antenna specifically made for CB operation. Operation of your CB equipment without a properly matched antenna may result in damaged transmitter circuitry. While portable CB’s generally come equipped with their own antenna, base stations and mobiles usually require antennas purchased separately. Selecting the right antenna is as important as selecting the right CB.

Mobile Antennas
There are some important considerations to be made when choosing a mobile antenna such as type of mount, physical size of antenna, type of car and performance expected.

Antenna Size
Electrically, all CB antennas must be the same size. Physically size, however, can be shortened with the use of loading coils. A loading coil is a coil of wire located at the top, center, or base of the antenna, the purpose of which is to electrically maintain desired length while physically shortening the vertical element. Generally, the longer the antenna, the better performance you can expect. The full sized 9 foot mobile whip antenna is not always practical, however, when you consider the height of most garage doors.

The type of vehicle will also determine your antenna selection. By their design, vehicles with fiberglass bodies, glass hatchbacks, vinyl tops or convertibles eliminate certain types of antennas and mounts.

Type of Mount
There are many numbers of ways to mount mobile antennas. The type of mount you select will usually determine the location of the antenna on the vehicle.

Note: When determining the location of your antenna and type of mount, remember that the higher and more centrally located the antenna is mounted on the vehicle, the better the performance and more omnidirectional it’s transmit and receive area.

The best performance, then, would require maximum size, maximum height and most central location, i.e., a 9 foot whip antenna mounted in the middle of the vehicle roof. As this may not be practical for most installations, tradeoffs in size, height, location and mounts must be made.

Two antenna types for autos which surpass the rest in popularity, performance, versatility, ease of installation, and appearance are the magnetic roof mount and the “no holes” truck lip mount. Mirror mounts and bumper or side mounted 9 foot whips are also popular for trucks and vans.

SWR Antenna Matching
Standing wave ratio (SWR) is technical term for a simple procedure. Basically, the transmitter output power of your CB is fed into your antenna coax, to the antenna itself and ultimately into the air waves. How well your antenna system accepts this power output should be measured periodically. Such measurement is called a standing wave ratio or SWR. Output power not accepted by the antenna system is built up as heat in the final output section of the transmitter.

Note: The power build up caused by severe antenna mismatch can damage your transmitter.

Antenna Coax Connectors
PL259 (male) SO239 (female): The common reference for CB antenna coax connectors or plugs. Mobile CB’s and base stations come equipped with SO239 jack plugs. Antenna coax is usually equipped with pre-installed PL259 connectors. Devices designed for in-line antenna coax operation are equipped with both an in and out SO239 jack.

CB Range
Transceiver range is often exaggerated by friends, salesclerks, and other CB’ers. This sometimes leads to disenchantment with equipment by the CB newcomer. But with proper understanding of the factors affecting CB range and realistic range expectations, the new CB’er will fully appreciate his unit and its capabilities.

The 4 primary factors affecting CB radio range are:
• Equipment (quality, type, and power output)
• Antenna height
• Terrain
• Atmospheric conditions

Quality is important in both the transceiver and the antenna. The type of antenna will also affect the range. A base station beam antenna will outdistance an omnidirectional one, single sideband equipment will surpass the range of AM CB and mobile or base antennas will outperform a short rubber duck antenna on a walkie-talkie. Where power output is concerned, a 4 watt mobile with a good SWR antenna match will outperform an identical 4 watt mobile with a poor SWR match.

The type of transceivers you are using is also a range factor. For instance, let’s say you and a friend are outdoors with walkie-talkies and can get a one mile portable to portable range. Your range back to the mobile CB at base camp, however, is three miles. You’ve also found out you can reach the ranger’s station, a base unit, eight miles away on top of Mt. anywhere. The increase range is primarily due to the superior antenna system of the mobile and the base station.
Simply put, the higher the antenna, the better the range. A mobile CB unit operating from the roof of a 4 story parking garage will get better range than the same unit at ground level.

The terrain in which you are operating will also play an important role. CB signals can be blocked or absorbed thus reducing their range. Much better range can be expected over a large body of water than in the mountains. Buildings, hills, and foliage cab greatly reduce the range of CB radio transmissions.

Atmosphere and weather conditions are other range factors. A freakish condition known as “skip” has been known to increase range over 1,000 miles. At other times, normal range can be significantly reduced by atmosphere or weather conditions.

So, CB range can be a matter of feet, miles, or sometimes hundreds of miles, depending on the equipment and conditions.

Below are listed some typical and realistic range estimates for different types of transceivers.
• 4 watt portable to portable 1/8 mile to 1 mile
• Congested urban area 2 miles to 7 miles
• Open flat rural area 5 miles to 13 miles
• 4 watt base to mobile 7 miles to 15 miles
• SSB mobile to SSB mobile 10 miles to 20 miles