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The Basics. Ward Silver NØAX. Antennas radiate (or receive) because electrons are accelerated (or are caused to accelerate) in the antenna’s elements. Radio or electromagnetic waves are both an E- (electric) and H- (magnetic) field. Electrons move parallel to E-fields. Strongest radiation from accelerating electrons linearly (back and forth)
The receiving antenna (Fig. 2–1b) is a region of transition from a space wave to a guided wave on a transmission line. Thus, an antenna is a transition device, or transducer, between a guided wave and a free-space wave, or vice-versa. The antenna is a device which interfaces a circuit and space.
ANTENNA INTRODUCTION / BASICS. Rules of Thumb: 1. The Gain of an antenna with losses is given by: 2. Gain of rectangular X-Band Aperture G = 1.4 LW Where: Length (L) and Width (W) are in cm 3. Gain of Circular X-Band Aperture G = d20 Where: d = antenna diameter in cm 0 = aperture efficiency 4.
BASIC ANTENNA THEORY. An antenna is a device that provides a transition between electric currents on a conductor and electromagnetic waves in space. A transmitting antenna transforms electric currents into radio waves and a receiving antenna transforms an electromagnetic field back into electric current. There are several basic properties that ...
Antennas are used for converting conducted electromagnetic waves into electromagnetic waves freely propagating in space and vice versa (Fig. 1.1). The name is derived from the field of zoology, where the term antennae (Latin) is used to designate the long thin feelers of insects.
An antenna is a device to transmit and/or receive electromagnetic waves. Electromagnetic waves are often referred to as radio waves. Most antennas are resonant devices, which operate efficiently over a relatively narrow frequency band. An antenna must be tuned (matched) to the same frequency band as the radio system to which it is connected,
Fig. 2.1.1 shows a simple wireless communication link comprising a transmitter, wireless channel, and a receiver. The transmitter consists of an RF generator, feed line, and an antenna that converts the guided wave coming from the feed to a radiating waveform in open space.
