The purpose of this dissertation is to extend the network analysis,
which is commonly used in circuit theory to free-space problems.
The benefits of such technique are that a sistematic approach can be applied to solve problems. 
It is possible to use different numerical technics to different regions of the problem accordint to 
its unique characteristics, and each part becomes a building block which can
be used later in a different problem by simply connecting the blocks in a circuit fashion.
To that aim, generalized admittence matrices are used to characterize the blocks.