Radiowave Transmission: Where Does Electric Field Come From?

In summary, the electric field in an electromagnetic wave emitted by an antenna comes from the AC voltage source. Unlike a normal wire, where the electric field comes from the source voltage, an antenna is not a closed circuit and charges flow out and back in at the same rate as the transmitted frequency.
  • #1
Jimmy87
686
17
Hi, I am having difficulty determining where the electric field comes from when an electromagnetic wave is emitted by an antenna. I know that the charges accelerate between an AC voltage but where does the electric part of the EM wave come from? In a normal wire there is no electric field from the charges themselves as they are canceled by the positive charges of the atoms. The electric field in the wire comes from the source voltage (e.g. a battery). So in an antenna does the electric field come from the AC voltage source?
 
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  • #2
Yes, the voltage source puts a charge on the antenna. Note that an antenna is not a closed circuit. Charges flow out of and back into each end at the same rate as the transmitted frequency.
 

Related to Radiowave Transmission: Where Does Electric Field Come From?

1. What is radiowave transmission and how does it work?

Radiowave transmission is the process of sending information or signals through the air using electromagnetic waves in the radio frequency range. This is possible due to the properties of electromagnetic waves, such as their ability to travel long distances and penetrate through obstacles. In order to transmit a signal, an antenna is used to create an electromagnetic field, which carries the information and is received by another antenna at the desired location.

2. Where does the electric field in radiowave transmission come from?

The electric field in radiowave transmission is generated by the movement of electrons in a conductor. When an alternating current is applied to an antenna, it causes the electrons to move back and forth, creating an electromagnetic field. This field consists of both electric and magnetic components, which work together to carry the signal through space.

3. How far can radiowaves travel?

The distance that radiowaves can travel depends on several factors, such as the frequency of the wave and the power of the transmitter. Generally, lower frequency waves can travel farther than higher frequency waves. The curvature of the Earth also plays a role, as signals can be blocked by obstacles and the curvature of the Earth limits the line-of-sight range.

4. What are the major applications of radiowave transmission?

Radiowave transmission is used for a variety of purposes, including communication, navigation, and broadcasting. It is the basis for radio and television broadcasting, as well as cell phone networks. It is also used for radar systems, which are used in aviation, weather forecasting, and military operations. Additionally, radiowaves are used for satellite communication and GPS systems.

5. Are there any potential health risks associated with radiowave transmission?

The World Health Organization has stated that there is no evidence to suggest that exposure to radiowaves from sources such as cell phone towers or Wi-Fi networks causes any negative health effects. However, some studies have suggested a possible link between long-term exposure to high levels of radiowaves and certain types of cancer. More research is needed to fully understand the potential health risks of radiowave transmission.

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