Why does the linear antenna radiate at k^2?

In summary, the radiation power of an antenna is the amount of electromagnetic energy it emits into free space, measured in watts. It is calculated using the formula P = G x E, where P is the power in watts, G is the antenna's gain, and E is the incoming electrical power. Factors such as size, shape, design, and frequency can affect the radiation power of an antenna. It is important because it determines the range and coverage of the transmitted signals. The radiation power can be improved by increasing the antenna's gain through design modifications and using higher quality materials.
  • #1
qnach
142
4
I am reading Jackson's book on classical electrodynamics.
It said in page 412 to 415 (3rd edition) that the total power radiated by a
dipole is proportional to k^4 (equation 9.24)
quadrupole is proportional to k^6 (equation 9.49)
But why does the linear antenna at page 412, which is a dipole, radiate at k^2 (equation 9.29)?
 
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  • #2
The dipole moment, p, has ω in the denominator (equation 9.27). Thus the c2|p|2 terms in 9.24 replace two of the k's.
 
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  • #3
so the (real) power for a dipole should be proportional to k^2 instead of k^4 ?
 
  • #4
Yes
 

Related to Why does the linear antenna radiate at k^2?

1. What is radiation power of an antenna?

The radiation power of an antenna refers to the amount of electromagnetic energy that is emitted or transmitted by the antenna into free space. It is typically measured in watts and is a measure of the antenna's ability to convert electrical energy into electromagnetic radiation.

2. How is radiation power of an antenna calculated?

The radiation power of an antenna can be calculated using the formula P = G x E, where P is the radiation power in watts, G is the antenna's gain, and E is the incoming electrical power in watts. The gain of an antenna is a measure of its ability to direct or focus the radiation in a particular direction.

3. What factors affect the radiation power of an antenna?

The radiation power of an antenna can be affected by several factors, including the antenna's size, shape, design, and the frequency of the radio waves it is transmitting. The type of material used to construct the antenna can also impact its radiation power.

4. Why is radiation power important for antennas?

The radiation power of an antenna is important because it determines the range and coverage of the radio waves it can transmit. A higher radiation power means that the antenna can transmit signals over a longer distance and with better clarity, making it more effective for communication purposes.

5. How can the radiation power of an antenna be improved?

The radiation power of an antenna can be improved by increasing its gain through design and construction modifications, such as using a parabolic reflector or adding more elements to the antenna. Additionally, using higher quality materials and optimizing the antenna's placement and orientation can also help improve its radiation power.

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