 wave can be very important because antennas are sensitive to polarization, and generally only receive or transmit a signal with a particular polarization. For most antennas it is very easy to determine the polarization. It is simply in the same plane as the elements of the antenna. So a vertical antenna (i.e. one with vertical elements) will receive vertically polarized signals best and similarly a horizontal antenna will receive horizontally polarized signals. Vertical and horizontal are the simplest forms of polarization and they both fall into a category known as linear polarization. However, it is also possible to use circular polarization. This has a number of benefits for areas such as satellite applications where it helps overcome the effects of propagation anomalies, ground reflections and the effects of the spin that occur on many satellites. Circular polarization is a little more difficult to visualize than linear polarization. However, it can be imagined by visualizing a signal propagating from an antenna that is rotating. The tip of the electric field vector will then be seen to trace out a helix or corkscrew as it travels away from the antenna. Circular polarization can be seen to be either right or left handed dependent upon the direction of rotation as seen from the transmitter. Another form of polarization is known as elliptical polarization. It occurs when there is a mix of linear and circular polarization. This can be visualized as before by the tip of the electric field vector tracing out an elliptically shaped corkscrew. It can be seen that as an antenna transmits and receives a signal with a certain polarization that the polarization of the transmitting and receiving antennas is important. This is particularly true in free space, because once a signal has been transmitted its polarization will remain the same. In order to receive the maximum signal both transmitting and receiving antennas must be in the same plane. If for any reason their polarizations are at right angles to one another (i.e