This question is to differentiate between a directive fan beam, pencil beam, and conical beams.
Directional antenna may change its direction with change in frequency but is still directional. Unidirectional will remain in the same direction at all the frequency.
Your questions relate to what we refer to as the antenna beam power pattern. This can be thought of as a plot of the radiated power on the inside of a sphere with radius much longer than the wavelength of the signal. The beam power pattern is often plotted in separate 2D representations of the horizontal and vertical beam power patterns. In the case of very high gain antennas, we say the antenna has a 'pencil beam' because the pattern is very concentrated in a narrow direction. The so-called 'unidirectional antenna' is only theoretical in 3D but a ground plane antenna can approximate a uniform 2D power pattern around 360 degrees in a horizontal plane. A great book on the subject of practical antennas is Radio Astronomy, by John Daniel Kraus (Ohio State), 1986. Good luck
- Badges
- Science topic
- Similar topics
- Engineering
- Telecommunications Engineering
- Antennas and Propagation