Two sets of waves in a Hertzian Dipole?

In summary, a hertzian pole in the near field has a changing electric and magnetic field in quadrature in both space and time. This creates one radiated wave in the far field, with the E:H vector ratio of 377:1. The changing induction fields do not create the radiating far fields, as they represent energy storage rather than power. This is described by Maxwell's equations.
  • #1
barton
14
1
In the near field, a hertzian pole has a changing electric field and a changing magnetic field, that are in both space and time quadrature. Are two sets of EM waves then created in the far field, one from the changing e-field, and one from the changing m-field?
 
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  • #2
There is only one radiated wave; The radiated Poynting vector P = E x H requires both an E vector and an H vector in phase. A quadrature phase field is an induction field (like in Faraday induction, where voltage is proportional to dB/dt), and cannot radiate power. The far-field radiated wave has the E:H vector ratio of 377:1 in the mks system. The polarization is along E.
 
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  • #3
Don't the changing induction fields create the radiating far fields, as described by Maxwell's equations?
 
  • #4
If two fields are in time (phase) quadrature, They represent energy storage, not power. The integral of [sin(wt) x cos(wt) dt] over 2 pi is zero. Consider the voltage and current for a pure inductance. They are in phase quadrature, and there is no real power.
 

FAQ: Two sets of waves in a Hertzian Dipole?

1. What is a Hertzian dipole?

A Hertzian dipole is a hypothetical antenna in the shape of a straight conductor that is infinitely long. It is used to model the behavior of real-life antennas, and is an important concept in the study of electromagnetic waves.

2. What are the two sets of waves in a Hertzian dipole?

The two sets of waves in a Hertzian dipole are the electric field waves and the magnetic field waves. These waves are perpendicular to each other and travel in the same direction as the dipole.

3. How are the two sets of waves in a Hertzian dipole related?

The two sets of waves in a Hertzian dipole are related by Maxwell's equations, which describe the behavior of electromagnetic fields. The electric and magnetic fields are interdependent and cannot exist without each other.

4. How does a Hertzian dipole emit waves?

A Hertzian dipole emits waves when an alternating current is applied to it. The movement of the electrons in the dipole creates a changing electric field, which in turn creates a changing magnetic field. These changing fields propagate as electromagnetic waves.

5. What are the applications of Hertzian dipoles?

Hertzian dipoles are used in many applications, including radio and television broadcasting, radar systems, and wireless communication devices. They are also used in scientific research to study the properties of electromagnetic waves.

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