# Antenna Polarization

Transmitting and receiving antenna should have same polarization(vertical or horizontal). Why?

I know that this is needed for maximum signal reception. But how? If electric field is in same plane of receiving antenna then magnetic field is perpendicular to antenna plane. So, we are not able to receive magnetic field to maximum. Am I wrong?

Free-space radio waves propagate in the TEM, or Transverse Electric Magnetic mode.

This means that the electric field and the magnetic field are both perpendicular to the direction of travel.

If the transmitting antenna is a simple electric dipole, the electric field is set up parallel to the dipole. This electric field is resolved onto the receiving dipole as cos(theta), where theta is the angle between the two dipoles.

So if the dipoles are lined up, theta=0, and the reception has gain=1.

If the receiving dipole is inverted, theta=pi, and the gain is -1.

If the receiver is at right angles, theta=pi/2, and the gain is zero.

• OK, But why do we not consider magnetic field instead of elecric field? – ironman Apr 22 '18 at 16:30
• @RedCircle - Which of the fields can induce a charge on a conductor? – HH- Apologize to Carole Baskin Apr 22 '18 at 16:48
• well @RedCircle, the eletrostatic field doesn't get polluted as much by electromagnetic noise generated by devices. – drtechno Apr 22 '18 at 19:02

A stadard dipole antenna converts the electric field into received power therefore, it has be correctly polarized with the plane of the electric field for optimum performance. A magnetic loop antenna is optimized when it properly aligns with the magnetic field and this is at 90 degrees to the electric field.

Maybe you think that a dipole (for instance) utilizes both magnetic and electric fields and therefore polarization is unimportant. Sorry for putting words into your mouth but this would be an incorrect analysis of an antenna.

Yes E and H are XY and weak axis is Z

• Sir, Why is transmitting and receiving antenna like dipole should have same orientation(polarization)? – ironman Apr 22 '18 at 14:43