The amount of signal received from a distant transmission source is essentially geometric in nature due to the inverse square law, and this leads to the concept of effective area. This measures the performance of an antenna by comparing the amount of power it generates to the amount of power in the original signal, measured in terms of the signal's power density in Watts per square metre. A half-wave dipole has an effective area of 0.13 2. If more performance is needed, one cannot simply make the antenna larger. Although this would intercept more energy from the signal, due to the considerations above, it would decrease the output significantly due to it moving away from the resonant length. In roles where higher performance is needed, designers often use multiple elements combined together. COUNT 3
QSN1 What accounts for the geometry involved in the use of an antenna? ANS1 inverse square law QSN2  How is the compactness of the signal measured? ANS2 Watts per square metre QSN3 What type of project would call for more than one element used together? ANS3 higher performance