Antenna polarization confusing

Question

How do we mount an antenna which is a meandered line shape, to be in vertical or horizontal polarization? Vertical pol means that the antenna mounted to vertically to the earth. I’m confused just because, for example, imagine that we have another printed patch antenna. When feeding thru Y axis, it becomes vertically polarized whereas if you feed thru X axis it becomes horizontally polarized. However, in the case of dipole antennas the current flows up and down thru the conductor, it is also said vertically polarized just because the current flows vertically to the earth ground. For a Yagi antenna, it flows parallel to the earth ground and called horizontally polarized. How should I think in such a meandered PCB antenna?

Answer 1

I get it for a regularly shaped antennas, however, how would I know it in case of a meandered line.

Not at all from looking at it alone.

First of all, this seems to be a multi-band antenna, which will definitely behave differently for different frequencies. You'll need to expect polarization to be a function of frequency.

Then, complex antennas like these will usually not be a "pure" thing. You'll have to simulate them at all the frequencies you care about. That's why every such antenna comes with an extensive datasheet or with frequency-dependentent S-parameters & dual-pol pattern measurement files, answering exactly the question "how does my antenna radiate at a given frequency".

Now, from the dimension of this, and from the fact that my best guess is that this is a quad-band antenna (can't read the overcompressed silkscreen print, but I guess it agrees): This is probably for cellular applications. So, the device this is connected to might be mobile to begin with, and be subject to an urban multipath scenario, where little to none of the original polarization reaches the communication partner (the cell tower), and where at least one side of the communication employs MIMO/digital beamforming anyway. If that is right, then there's little motivation to give you a "purely" polarized antenna, anyways, and chances are this thing is mostly elliptically polarized at arbitrary angles. Again, differing on different frequencies.

The assumption "an antenna needs to be linearly polarized, and that linear polarization will be either vertical or horizontal" simply doesn't hold, and you should in general not assume it does.