An antenna is an electrical device that converts electrical power into radio waves and vice-versa. An antenna radiates most efficiently when its physical dimensions correspond to the characteristics (frequency, wavelength etc.) of the wave that it is receiving or transmitting. In accordance with this principle we take the antenna`s length as Wavelength/4 here. Another main criteria in antenna design is impedance matching. Power is coupled to (or from) an antenna efficiently from a transmitter or receiver only if its impedance matches to that of the antenna. If this is not the case, then the power is reflected back to the source. This is determined by the value of reflection coefficient. If the value is more negative, it indicates that most of the power is coupled to the antenna so that the wave reflected back to the source is pretty much weak.
The task carried out after antenna design is its placement on the desired platform. The impedance characteristics of the antenna changes when it is mounted on platforms. Further, the radiation pattern may also get distorted due to the platform on which antenna is mounted. Hence, an optimum position for placing an antenna needs to be determined considering the aforementioned issues. This is achieved by varying the position of the antenna on the platform and estimating its performance. This exercise is carried out until satisfactory results emerge.