A report on Parabolic antenna and Point-to-point (telecommunications)

Erdfunkstelle, a large parabolic satellite communications antenna in Raisting, Bavaria, Germany, the biggest facility for satellite communication in the world. It has a Cassegrain type feed.
A 1 Gbit/s point-to-point millimeter-wave link installed in the UAE
Parabolic antennas are based on the geometrical property of the paraboloid that the paths FP1Q1, FP2Q2, FP3Q3 are all the same length. So a spherical wavefront emitted by a feed antenna at the dish's focus F will be reflected into an outgoing plane wave L travelling parallel to the dish's axis VF.
A point-to-point wireless unit with a built-in antenna at Huntington Beach, California
Wire grid-type parabolic antenna used for MMDS data link at a frequency of 2.5-2.7 GHz. It is fed by a vertical dipole under the small aluminum reflector on the boom. It radiates vertically polarized microwaves.
Main types of parabolic antenna feeds.
Array of multiple feed horns on a German airport surveillance radar antenna to control the elevation angle of the beam
Effect of the feed antenna radiation pattern (small pumpkin-shaped surface) on spillover. Left: With a low gain feed antenna, significant parts of its radiation fall outside the dish. Right: With a higher gain feed, almost all its radiation is emitted within the angle of the dish.
Radiation pattern of a German parabolic antenna. The main lobe (top) is only a few degrees wide. The sidelobes are all at least 20 dB below (1/100 the power density of) the main lobe, and most are 30 dB below. (If this pattern was drawn with linear power levels instead of logarithmic dB levels, all lobes other than the main lobe would be much too small to see.)
The angle theta is normal to the aperture.

Parabolic antennas are used as high-gain antennas for point-to-point communications, in applications such as microwave relay links that carry telephone and television signals between nearby cities, wireless WAN/LAN links for data communications, satellite communications and spacecraft communication antennas.

- Parabolic antenna

This can be a microwave relay link consisting of a transmitter which transmits a narrow beam of microwaves with a parabolic dish antenna to a second parabolic dish at the receiver.

- Point-to-point (telecommunications)
Erdfunkstelle, a large parabolic satellite communications antenna in Raisting, Bavaria, Germany, the biggest facility for satellite communication in the world. It has a Cassegrain type feed.

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The atmospheric attenuation of microwaves in dry air with a precipitable water vapor level of 0.001 mm. The downward spikes in the graph corresponds to frequencies at which microwaves are absorbed more strongly, such as by oxygen molecules.

Microwave transmission

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Transmission of information by electromagnetic waves with wavelengths in the microwave range of the electromagnetic spectrum.

Transmission of information by electromagnetic waves with wavelengths in the microwave range of the electromagnetic spectrum.

The atmospheric attenuation of microwaves in dry air with a precipitable water vapor level of 0.001 mm. The downward spikes in the graph corresponds to frequencies at which microwaves are absorbed more strongly, such as by oxygen molecules.
A parabolic satellite antenna for Erdfunkstelle Raisting, based in Raisting, Bavaria, Germany
C-band horn-reflector antennas on the roof of a telephone switching center in Seattle, Washington, part of the U.S. AT&T Long Lines microwave relay network
Dozens of microwave dishes on the Heinrich-Hertz-Turm in Hamburg, Germany
Communications tower on Frazier Mountain, Southern California with microwave relay dishes
Danish military radio relay node
Production truck used for remote broadcasts by television news has a microwave dish on a retractible telescoping mast to transmit live video back to the studio.
Antennas of 1931 experimental 1.7 GHz microwave relay link across the English Channel. The receiving antenna (background, right) was located behind the transmitting antenna to avoid interference.
US Army Signal Corps portable microwave relay station, 1945. Microwave relay systems were first developed in World War II for secure military communication.
Richtfunkstelle Berlin-Frohnau
Microwave spying

Microwaves are widely used for point-to-point communications because their small wavelength allows conveniently-sized antennas to direct them in narrow beams, which can be pointed directly at the receiving antenna.

Typical types of antenna used in radio relay link installations are parabolic antennas, dielectric lens, and horn-reflector antennas, which have a diameter of up to 4 meters.