its input impedance is similar to the transmission line’s input impedance, etc. The disadvantages of a half-wave antenna are is that it is an independent antenna, so it can be used as the fundamental element for other types of antennas that work at extremely high frequencies and the nature...
Basically, the better the radar antenna is at transmitting and focusing its energy in a certain direction, the better range it has. 天线的基本概念 - 了解天线在卫星通信领域的重要性 Antenna Concepts - Importance of Antennas in Satellite Communications As with Radar, many satellite system properties...
The radiated power of most antennas is not uniform in all directions and has different intensities. The radiated power in various directions is called the pattern of the antenna. Each antenna should be mounted so that its direction of strongest radiation intensity points toward the other antenna ...
At a particular frequency an antenna exhibits reciprocity; that is, its receive and transmit properties are identical. An antenna may have gain, expressed as G=η4πA/λ2. Here η is the antenna efficiency (usually in the range from 0.60 through 0.75), A is the antenna aperture area, and...
This new type of system antenna could achieve a certain range of electrical scanning and higher gain through its reflective surface. For example, in communication satellites, phased-array feeds can be used to automatically control the beam direction and increase the number of beams, and a ...
An orbiting vehicle, which relays signals between communications stations. There are two types: a. active communications satellite--A satellite that receives, regenerates, and retransmits signals between stations; b. passive communications satellite--A satellite which reflects communications signals between...
Lattice towers are similar to vertical mast structures, however, these systems are more typically triangular, or of an extended-box configuration. In the latter case, this produces a wider base than its top, and the entire structure is constructed by creating a series of horizontal ladders, or...
Design and measure a wideband dual polarized microstrip antenna that finds its use at the base station of a cellular system. In order to achieve the wideband characteristics, this design considers a slot coupled patch antenna structure. Modeling and Analysis of Single Layer Multi-band U-Slot Patch...
The isotropic antenna and its perfect spherical pattern are only theoretical, but the model serves as a useful conceptual standard against which “real world” antennas and their specifications can be compared (Figure 7). Now it is time to take a closer look at some of the most important ...
For applications where high antenna gain is required, a parabolic reflector design is usually chosen because of its simplicity, low mass, and relatively low cost. For applications where the antenna “beam” (direction of greatest sensitivity) must be steered, a phased array antenna, which is ...