It’s obvious that the antenna system is an important part of an RF communication system — without it the system wouldn’t work. Equally obvious is the fact that the antenna system is common to both the transmitter and the receiver; any change made in the antenna system affects both transmission and reception.
An antenna is formed of a few basic parts:
The antenna is the portion of the radio system found at the top of the tower. It could be a simple one-element antenna, or it could be a complex multi-element array. The antenna takes radio energy from the transmission line and radiates it into space; it also receives radio energy from space and feeds that received energy down the transmission line to the receiver. To oversimplify, an antenna is designed to radiate radio energy into space and collect radio energy from space.
What is remarkable, though, is how efficiently this occurs. A two-way antenna is nearly 100 percent efficient. Of course, not quite all of the energy that is put in, is transmitted.
Factors affecting this include a coaxial line that doesn’t perfectly “match” the input to the antenna, and power lost due to such things as “skin effect,” insulator dielectric, eddy currents, etc. But, since we can typically claim that a omnidirectional antenna radiates better than 95 percent of the watts it receives from the coaxial line — provided it “matches” the line — an antenna is an efficient device when compared to most other energy-emitting things we know. Sector antennas are not quite as efficient but deliver benefits in other area.
How these parts are designed together impact the network coverage and capacity of wireless networks.