There exist two main types of antenna/wave polarization.
Linearly polarized waves are the ones we are used to seeing in most animations. These waves contain two elements, an electric wave, and an orthogonal magnetic wave travelling alongside one another. If the direction of a wave is in the "+z axis", its electric field wave may oscillate along the y axis, and its magnetic field's wave may oscillate along the x axis. An animation of a linearly polarized propogating wave is shown below.
Linearly polarized wave. Credit: WikiMedia (https://commons.wikimedia.org/wiki/File:EM-Wave.gif)
Remember that an antenna picks up on the change in the magnetic field of a wave in order to produce an electric signal that can be deciphered into meaningful data. Also recall Faraday's Law, which says that a changing magnetic field must be perpendicular (or at some angle) to the area enclosed by a loop of wire in order to induce a current in a wire. Considering the animation above, if we consider a loop of wire along this path located on the y-x plane, the current orientation of the linearly polarized wave will allow us to measure a current, as the B-field currently propogates along the z-axis. If, however, the B-field were to propogate along the y-axis or the x-axis, no electric current would be induced. As such, polarization of waves is of particular importance to an RF engineer. To counter this problem, RF systems can sometimes include several linearly polarized antennas pointing in different directions, such as those on a professional drone ground station:
In practice, these two antennas would be pointed in different directions to facilitate linear polarization in two axes. Source: DGI (https://www.dji.com/ca/dji-lightbridge)
The polarization of antennas in an RF system affects the Polarization Loss Factor (PLF) of the link. PLF is given by $cos^2(\phi)$, where $\phi$ is the angle of rotation between the transmitting and receiving antennas in the system.
An additional set of terms, "vertical" and "horizontal" polarization, are used in ground RF systems to denote when the electric field of an antenna propogates parallel or perpendicular to the ground, though this is not too important to CubeSat communications.
Sometimes, antennas can be designed such that their EM waves have propogating components along two axes. This allows their waves to rotate along the axis of rotation. This results in a wave that looks something like the following:
Circularly polarized wave. Source: WikiMedia (https://en.wikipedia.org/wiki/Circular_polarization)
A circularly polarized wave is generated by the transmission of waves along two axes, 90 degrees out of phase. Source: Edmund Optics (https://www.edmundoptics.com/knowledge-center/application-notes/optics/introduction-to-polarization/)
In comparison to a linearly polarized wave, this type of transmission allows for detection in all types of orientations (assuming your receiver is also circularly polarized). It is however, possible to detect a circularly polarized wave using a linearly polarized antenna, but this results in a PLF of -3dB.
Note that elliptical polarization is very similar to circular polarization, but circular comes about from equal components of the wave being transmitted in both directions, and elliptical waves are created when the components of the wave are not equal.
Summary of the types of polarization. Source: https://gfycat.com/gifs/search/circular+polarization
Circularly polarized waves have two different orientations for transmission. Depending on the phases of the components of the wave, they can either be left or right-hand polarized (clockwise or anti-clockwise). There are two different conventions for defining these directions.
The more commonly used version is from the point of view of the source. In this version, if you point your right thumb in the direction of propagation, a right-hand or clockwise polarized wave is defined by the direction that your fingers curl in.
If polarization is defined from the point of view of the receiver, a right-hand polarized wave is defined by the direction your fingers curl when you point your thumb in the direction of the source.
The direction of polarization is important. A left-hand polarized antenna cannot receive signals from a right-hand polarized source. Their handedness must be the same.
Circular polarization does provide a slight advantage in losses due to reflection. When a circularly polarized wave bounces off a surface, its handedness changes, and this results in a reduced amount of destructive interference between the waves.
