FYP 1: history of antenna

First of all, some introduction to the antenna is great need since I don't really have the basic. I think my lecturer  was lounging at me every time when I asked some related questions even though he did not express out. However, this is really not our fault. We have only learned antenna through the laboratory, not the proper lecture. Hence, it's not surprising that I am so noob.

Well, let start my FYP project.

History of the antenna: Hertz and Marconi invented. Antenna seem to have a bewildering 使人困惑 的, but all operate according to same basic principle of EM.

Antennas are our eye and ear on the world. They are links with space. They are essential基本的, integral part of our civilization. Antenna has been around for long time, millions of years, as the organ for touch or feeling of animals, birds, and insects. Last 100 years, acquired a new significance as the connecting link between a radio system and the outside world.

1^st   antenna built by Heinrich Hertz. In 1886, he assembles apparatus we would now describe as a complete radio system operating at meter wavelengths with an end-loaded dipole as the transmitting antenna and a resonant square-loop antenna as receiver.

Receiver: resonant square-loop antenna; transmitting: end-loaded dipole.

His invention remained a laboratory curiosity until 20 years old Guglielmo Marconi went to add tuning circuits, big antenna and ground systems for longer wavelengths, and was able to signal over long distances. In mid –December 1901, he startled the world by receiving signals at St.Johmx, Newfoundland from a transmitting station he had constructed at Poldhu in Cornwall, England. A year later, he began regular transatlantic message service in spite of a suit诉求 by the Cable Company for infringing侵害 on its monopoly of transatlantic messaging.

With the advent of the radar after World War II, centimeter wavelength became popular and the entire radio spectrum opened to wide usage. Our probes 探查with their array一系列 of antennas have visited the planets of the solar system and beyond, responding to our commands and sending back photographer and data at centimeter wavelengths even though it may take over 5 hours for the signal to travel one way. And our radio telescope antenna operate at millimeter to kilometer wavelengths receive signal from object to distant that it has taken more than 10 billion years for the signal to arrive.

After Heinrich Hertz 1^st demonstrated radiation from antenna, it was called wireless. And wireless it was until broadcasting began about 1920 and the word radio was introduced. Now wireless s back to describe the many systems that operate without wires as distinguished from radio, which to most persons now implies AM or FM.

Dimensions规格 and Unit

Dimension defines some physical characteristic such as length, mass, time, velocity and force.

Fundamental 6 dimension: length, time, mass, luminous intensity, electric current, temperature.

Secondary dimension: other dimension

Unit: standard/ reference by which the dimension can expressed numerical. For eg, the length (dimension) of a steel rod might be 2 meters, and its mass (dimension) 5 kilograms.

Fundamental and Secondary Unit

Fundamental/base unit: Unit for fundamental dimension. SI unit (International System of units, SI unit are used. The six fundamental units are meter, second, kilograms, candela, ampere, Kelvin

The unit for other dimensions are called secondary or derived units and based on these fundamental units.

   

Reference: Antenna for All Aplications third edition (John D.Kraus & Ronald J. Marhefka)