A simple dual band antenna is designed. How can we determine its polarization at two frequency bands? Can we consider it linear by deafult?
The polarization is determined by the direction of the electric field in the space.
Vertically polarized antennas have their E-field in the vertical direction while horizontally polarized antenna has its E field in the horizontal direction. If there is only one polarization in time it will a linear polarization. If the two components are existing at the same time while having the the same magnitude the polarization will be circularly polarized.
The polarization do not depend on the frequency of the radiation
So, in order to determine the polarization of an antenna you have to look at the direction its electric field.
best wishes
No, you can't consider it linear by default. Many simple antennas do not radiate linear polarization. To find the polarization you need to measure two orthogonal polarizations, and the phase between them, at each point where you want to know.
A linear dipole, a loop dipole, and a microstrip patch, all radiate with linear polarisation.
well.. a story with microstrip patches can become a bit complicated... I would remove them from the list.
I should have said simple rectangular half-wave microstrip patches on a large ground plane - I believe that is linearly polarized, i.e. two parallel, in-phase, magnetic dipoles, or am I mistaken Andrey Porokhnyuk ?
only in the case of perfect symmetry, including feed. probably, from this position, narrower is better. it is linear when transverse currents cancel each other. there are tricks of gaining circular polarization, by shifting the feed, cutting corners, or putting asymmetric bumps on the side. simple tecnnological error can create ellipticity.
But not to have a small twist in it that would give a circular component.
The polarization is determined by the direction of the electric field in the space.
Vertically polarized antennas have their E-field in the vertical direction while horizontally polarized antenna has its E field in the horizontal direction. If there is only one polarization in time it will a linear polarization. If the two components are existing at the same time while having the the same magnitude the polarization will be circularly polarized.
The polarization do not depend on the frequency of the radiation
So, in order to determine the polarization of an antenna you have to look at the direction its electric field.
best wishes
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