Antenna Fundamentals: Signals, Topology, Types and Troubleshooting
Waves and Signals
Frequency: The number of cycles a signal completes in a given period of time, measured at a specific moment in time.
Wavelength: The distance between two points of a wave that are in the same phase.
Power: Power is the same as voltage across the terminals. Signals carry the power provided.
Impedance: The resistance offered to the current flow.
Level: The level is the sum of all cycle values.
Effective level: The same DC value that generates the same power as the original signal.
Topology
Distribution network: Two or more devices distribute the signal to two or more receptor points.
System uptake: Elements receive the signal and transmit it through cables.
Formed by antennas, which transform signals into electromagnetic waves.
Mechanical components: Signals are attached to the antenna by means of masts.
Low-noise amplifiers: Devices placed at the receiving antenna that amplify the signal coming from the cables.
Signal amplification: Elements raise the signal, process it, and convert it from analog to digital.
Antenna Transmitters and Components
Components convert signals into electromagnetic waves and capture them.
Director elements: Metal pieces, phased, that direct the signal toward the dipole.
Reflector elements: Protect the dipole from signals in other directions.
Dipole: The sensor and signal adapter.
Impedance: Located on the dipole, inside the connection box.
Antenna Characteristics
Gain: The ratio between the power received and the power delivered to the load connected to the antenna.
Directivity: The ability of an antenna to concentrate power in one direction. Includes the azimuth angle and the front-to-back ratio.
Bandwidth: The margin within which the antenna can operate at its maximum.
Antenna Types
Dat 45 antenna: Has a director stacking that maximizes bandwidth, high gain, and good directivity.
Yagi antenna: Consists of one dipole, a reflector, and director elements. Has good directivity.
Panel antennas: Characterized by their flatness, directivity, a small bandwidth, and average gain.
Electronic antennas: Elements are integrated into a circuit and have little directivity.
Logarithmic antenna: Covers the whole band with low gain and low directivity.
Common Problems
Ghosts (double image)
Cause: The antenna is misaligned and receives a reflected signal.
Solution: Optimize the pointing, use a more directional antenna, and place the antennas in an armored box.
Noise or weak signal
Cause: Long distance from the transposer and low-coverage areas.
Solution: Use antennas with more gain and low-noise amplifiers.