the antenna they propagate in a specific direction and in a  specific pattern. This is the antenna field. The orientation  of the electric and electromagnetic fields remains at 90° to  each other but radiate from antenna with varying strength in  different directions. The strength of the radiated field varies  depending on the type of antenna and the angular proximity  to it. All antennas, even those that are omnidirectional,  radiate a stronger signal in some direction compared to other  directions. This is known as the antenna field directivity. Receiving antennas with the same polarization as the  transmitting antenna generate the strongest signal. A  vertically polarized antenna is mounted up and down. It  radiates waves out from it in all directions. To receive the  strongest signal from these waves, the receiving antenna  should also be positioned vertically so the electromagnetic  component of the radio wave can cross it at as close to a  90° angle as possible for most of the possible proximities.  [Figure 11-88] Horizontally polarized antennas are mounted side to side  (horizontally). They radiate in a donut-like field. The  strongest signals come from, or are received at, 90° to the  length of the antenna. There is no field generated off of the  end of the antenna.  Figure 11-89  illustrates the field produced  by a horizontally polarized antenna.  Many vertical and horizontal antennas on aircraft are  mounted at a slight angle off plane. This allows the antenna  to receive a weak signal rather than no signal at all when the  polarization of the receiving antenna is not identical to the  transmitting antenna.  [Figure 11-90]  There are three basic types of antennas used in aviation:  Types 1.  Dipole antenna 2.  Marconi antenna 3.  Loop antenna  11-40 Figure 11-90.  Many antenna are canted for better reception.  Figure 11-88.  A vertically polarized antenna radiates radio waves  in a donut-like pattern in all directions.  Figure 11-89.  A horizontally polarized antenna radiates in a  donut-like pattern. The strongest signal is at 90° to the length of  the conductor.  90° Minimum radiation Maximum radiation Up Down E W N S