Modulation in high frequencies and antennas

In summary: This is due to the principle of wave propagation. If the antenna length is larger than the wavelength of the transmitted signal, the waves will be scattered in all directions instead of travelling in a straight line.
  • #1
dervast
133
1
Hi to everyone. I have heard that we usually prefer to modulate signals at high frequencies so the wave length is small compared to the length of the antenna. Is there any rule or equation that implies this requirement?
 
Engineering news on Phys.org
  • #2
To be an efficient radiator, an antenna will generally be a half-wave dipole or a quarter-wave monopole. That is, a dipole antenna will have two opposed elements, each a quarter-wavelength long. A monopole will have a single radiating element a quarter-wavelength long, over some ground plane or set of ground elements.

http://en.wikipedia.org/wiki/Antenna_(radio)
 
  • #3
dervast said:
Hi to everyone. I have heard that we usually prefer to modulate signals at high frequencies so the wave length is small compared to the length of the antenna. Is there any rule or equation that implies this requirement?

Modulation has little to nothing to do with the antenna. The carrier frequency and the antenna are related as berkeman pointed out.
 
  • #4
Averagesupernova said:
Modulation has little to nothing to do with the antenna. The carrier frequency and the antenna are related as berkeman pointed out.
I agree with u.. the antenna has nothing to do withthe modulation scheme. I was talking about modulation describing that we modulate signals in high frequencies
 
  • #5
So you are saying that the reason we use certain frequencies in the spectrum for the carrier is to keep the antenna size in check? The main reason we use the ones we do is propagation of the wave. Some signals we want to go over the horizon, some we don't. Some signals we want refracted off the ionosphere, some we don't. However, there ARE cases were antenna size is a consideration. I would not say it is the main reason. Throwing the word modulation in there has thrown me off.
 
  • #6
dervast said:
...wave length is small compared to the length of the antenna. Is there any rule or equation that implies this requirement?
As Berkeman has implied, the antenna length of efficient radiating elements is not larger than the wavelength of the transmitted signal.
 

FAQ: Modulation in high frequencies and antennas

1. What is modulation in high frequencies?

Modulation in high frequencies refers to the process of changing or varying the properties of a high frequency signal, such as amplitude, frequency, or phase. This allows for the transmission of information through the airwaves.

2. Why is modulation necessary for high frequency communication?

Modulation is necessary because high frequency signals are easily attenuated and distorted as they travel through the air. By changing the properties of the signal, modulation makes it easier for the signal to be received and decoded accurately.

3. What are the different types of modulation used in high frequency communication?

The most common types of modulation used in high frequency communication are amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM). Other types include single-sideband modulation, quadrature amplitude modulation, and pulse modulation.

4. How do antennas play a role in modulation of high frequencies?

Antennas are essential for both transmitting and receiving high frequency signals. They are responsible for converting electrical signals into electromagnetic waves for transmission, and then converting received electromagnetic waves back into electrical signals for decoding.

5. What factors affect the effectiveness of modulation in high frequency communication?

The effectiveness of modulation in high frequency communication is affected by factors such as the distance between the transmitter and receiver, the strength of the signal, and the presence of interference or noise. The type and quality of the antennas used also play a significant role.

Similar threads

Back
Top