# Source Concept

Imagine you have 10 cm2 of metal. How do you bend it to recieve an antenna delivering maximum portion of electromagnetic energy towards a given direction and, at the same time, ensure radiation efficiency and bandwidth above specified threshold?

So, why source concept? The piece of metal mentioned above, could be understood as a source (region). However, from physical point of view, our sources - those we would like to control - are the currents. Therefore, the rest of the article is more of less devoted to the currents and possible operations with them. With that respect, the key instruments are the electromagnetic and antenna operators, represented by a set of piecewise basis functions. They are expressed as matrices, allowing thus all standard algebraic operations, e.g., matrix inversion and decomposition.

### What the Source Concept Is?

Source Concept represents a promising framework providing a unified theory of the evaluation, decomposition and manipulation with electromagnetic source currents in ways as yet imagined.

It is a mixture of powerful techniques, both analytical and numerical, together with the idea that the electromagnetic current can be substituted into any expression relevant to small antenna design. The ultimate goal presents the ability to manipulate with the currents completely freely in order to determine both the fundamental bounds on (small) antennas and their optimal performance with considering realistic feeding, material distribution and fabrication processes.

### Development of the Source Concept

• circuit quantities ($V_\mathrm{in}, Z_\mathrm{in}, \Gamma,\dots$)
• field quantities ($\boldsymbol{E}, \boldsymbol{H}$)
• source current quantities ($\boldsymbol{J}, \boldsymbol{M}$)

$$p = \langle \boldsymbol{J}, \mathcal{L} (\boldsymbol{J}) \rangle, \quad \boldsymbol{J} = \boldsymbol{J} (\boldsymbol{r}), \quad \boldsymbol{r}\in\varOmega.$$

### What Are Advantages of the Source Concept?

capability to deliver operator's inversion, decomposition (EP, GEP), model-order reduction, structural decomposition, optimal currents, antenna optimization, direct integration X construction of operator and using bilinear form

WIP (Box: Did you know? Schwinger's sourcery, Box: Operators in matrix form - example (Z), Box: From geometry, triangulation (Delaunay), through edge-finding, application of basis functions, to currents. Table: List of matrix operators)