CB radio antenna – How does it work?

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This article will explain you about:

  • What is CB Radio Antenna?
  • How does a CB radio antenna work?

So let’s take a start from

What is CB Radio Antenna?

CB radio antenna is the crucial part of a CB system that is construct for two things.

  • The abduction of radio frequency signals which are later converted into electrical current by the receiver.
  • Carry the electrical signals from the transmitter and turn it into radio frequency signals

How does it work?

The Second activity which is mentioned above plays a very important role because it is the function where tuning takes place. Something that’s done best when the length of the antenna precisely matches the wavelength of the transmitted radio frequency.

You can easily resolve the appropriate height of an Antenna by applying this formula:

Wavelength (in feet) = 984 / frequency (in megahertz)

As we all CB’ers know about the spectrum that from where it begins, mean 25.01 Megahertz. So the length or you can say a height of an antenna must be more than 39.34 feet long.In the case of CB, the 1/4 antenna at just under 10 feet long is the common “whip” that you may see on cars and trucks.

It is not important that for every frequency, there is a separate antenna. So antenna costumier must have to compromise. Generally choosing the frequency in the middle of a transmission and choosing the length of the antenna to correlate. When an understanding like this is contrived, then you must have to see whether it’s a good understanding or not. This is fulfilled by calibrating the Standing Wave Ratio (SWR) and the wire (cable) between the antenna and tuning the antenna as far as the SWR is kosher.

Each antenna and its feedline have an attitude “Obstruction (Impedance)” or hostility to electrical current. In an optimal position, the Obstruction (Impedance) of line & antenna bout entirely and about 100% of the electrical energy is indoctrinated into radio energy emanate into the atmosphere. In less than ideal case, when Obstruction isn’t bout entirely then some amount of electrical energy will not be converted into radio energy, but will be echoed back down the feed line. That will be the causation of standing waves of electrical energy in the feed line. Let’s take an example of river rapids. When the water in the river ravine, over and ‘tween promontory (rubble, pebbles) the wave which produce from it doesn’t behave like a yo-yo. We mean up and down in the river. It just stays in one place. This was a standing wave of water. The ratio of the highest voltage on the line to lowest is the Standing Wave Ratio. In the perfectly matched system, the SWR is 1:1.

For tuning the CB radio antenna

Use SWR meter attached between the transmitter and the feed line. Depending on the meter, you can use the button on the meter to inaugurate a signal on different channels. Or attach the mic on the CB transceiver to produce the waves, at the same time you look at the SWR reading. In the normal situation, if the SWR never goes high from 1:5:1, then maybe your tuning process is going on a right path. If the SWR is higher than 1:5:1, then you must have to watch the SWR meter on various prevalence. The SWR will be leading on higher channels or lower. If you feel that SWR is maximum at lower channels, then you must have to focus on the length of an antenna, mean you have to increase the length of CB radio antenna bit by bit. And if the SWR is greater on higher channels, then you must have to decrease the length of CB radio antenna bit by bit.

Note: The configuration around your antenna can easily effect all the obstruction (impedance) of an antenna.

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One thought on “CB radio antenna – How does it work?

  1. Ron Wright, N9EE

    Well lots of info left out like normally a whip or vertical antenna is 1/4 wave length, 1/4th the equation given. Kinda said this, but would know only if knew before.

    I think this article was written in different language and translated, poorly translated. One issue is the term “height” of antenna, I should read the length of the antenna. Height is how high the antenna is above ground or other structure. Length is how long in this case the whip is. Again it is 1/4 wave length or 0.25 x 984/F(MHz) for 1/4 wave lenght.

    And we do not use 25 MHz in US, maybe another clue article in another language. In US CB is around 27 MHz.

    Explanation of impedance is very poor one. There is an impedance of a feedline/coax, but this is not an obstruction. There is an obstruction to the RF going down the feedline, but this is loss and due to many factors. the main issue with impedance of feedline is to make sure it is same as the antenna (the antenna has an input impedance) and the output of the transmitter (a transmitter is designed to drive a certain impedance and is most typical 50 Ohms). The proper impedance of a feedline makes more of the RF power go down the feedline into the antenna.

    The article would be good if someone knowing the language more cleaned it up and corrected a few details.


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