# Antenna Amplitude: Factors Affecting Wave Size

• mtanti
In summary, the size of the amplitude of a wave sent by an antenna is affected by the frequency of the signal sent to it, the length of the antenna, and the impedance matching between the source and the antenna.
mtanti
What affects the size of the amplitude of a wave sent by an antenna?

The amplitude of the signal fed to it.

- Warren

And the efficiency of the antenna.

The impedence matching between the source and the antenna(kind of inclusive with the above two). The length of the antenna vs the frequency of the signal sent to it.

faust9 said:
The impedence matching between the source and the antenna(kind of inclusive with the above two). The length of the antenna vs the frequency of the signal sent to it.

You're saying that the frequency has to do with the amplitude? Whats the formula anywayz?

mtanti said:
You're saying that the frequency has to do with the amplitude? Whats the formula anywayz?

Yes I am. Antennas have to be 1/2 of the signal wavelenght for optimum transmission (1/4 waves use ground for the other 1/4 of the antenna length) http://www.electronics-tutorials.com/antennas/antenna-basics.htm

So, if your antenna is not the correct length then part of the energy put into the antenna will be lost. http://www.ycars.org/EFRA/Module%20C/AntVert.htm

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To Mtanti
It is useful to think of the equivalent circuit of the antenna as a series circuit it comprises 4 parts L C R1 R2 , R1 is the radiation resistance , R2 is the loss resistance L and C are the inductive and capacitive elements .
Ideally L and C tune out if the signal frequency matches the antenna type and configuration . The part of the signal important is that across R1 typically a few 10's of Ohms , usually r2 is not too high and in many cases can be ignored , but the tuning
is important since typical antennas like a dipole are quite high Q meaning that the L impedance is higher than R1 and this must by canceled by the C impedance .
In cases where it matters the antenna impedance will be measured and any tuning
done ( sometimes by an externally added C component or matching circuit ) .
Antennas do NOT have to be tuned alone -- small antennas as used in portable equipment (pagers ) cannot self tune -- so they are tuned by other components -- they can still be efficient . in Antenna design suitable software is often used which
indicate impedances losses and directional information .
Ray.

## 1. What is antenna amplitude and how does it affect wave size?

Antenna amplitude refers to the maximum height of a wave above its resting point. It is directly related to the amount of energy carried by the wave. The higher the amplitude, the larger the wave size will be.

## 2. What are the main factors that affect antenna amplitude?

The main factors that affect antenna amplitude include the distance between the antenna and the source of the wave, the frequency of the wave, and the material properties of the medium through which the wave is traveling.

## 3. How does the distance between the antenna and the source affect wave size?

The distance between the antenna and the source of the wave can have a significant impact on the amplitude of the wave. As the distance increases, the energy of the wave is spread out over a larger area, resulting in a decrease in amplitude and a smaller wave size.

## 4. How does frequency affect antenna amplitude?

Frequency is directly related to antenna amplitude. As the frequency of a wave increases, the amplitude also increases, resulting in a larger wave size. This is because higher frequency waves have more energy and can travel farther, resulting in a larger amplitude.

## 5. How do material properties affect antenna amplitude?

The material properties of the medium through which a wave travels can also affect antenna amplitude. Different materials have different densities and resistances, which can either amplify or dampen the amplitude of a wave. This can result in changes in wave size depending on the properties of the medium.

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