IBM Release 1.93 Worked Example Optimizing a V Antenna, F i g u r e 2 . 1 2 Optimized V-antenna

3.6.2. Worked Example: Optimizing a V Antenna

Thermodynamics dictates that the total power an antenna can deliver to its terminals when excited by isotropic thermal radiation cannot be larger than kT per hertz (otherwise you could put a hot resistor at the feed point, point the antenna at a colder object, and have the resistor get hotter spontaneously). Thus there is a 1:1 trade-off between antenna gain and solid angle: the product of the effective intercepted area of an antenna and the equivalent width of its angular pattern in steradians cannot exceed λ2/2. The angular pattern of an ordinary dipole has a solid angle of π steradians, so its gain is only 2. We can do better, for narrower angular patterns, by raking the ends of the dipole forwards into a V shape. This optimization run is adjusting the width and rake of the arms, and the feed point impedance, to maximize the power dissipated in the load.

The parameters file used in this simulation is in Appendix A, along with the simplex file, showing the progress of the optimization.

Figure 2.10 Optimized V antenna: refractive	Figure 2.11 Optimized V antenna: E field
	amplitude
index distribution

F i g u r e 2 . 1 2 Optimized V-antenna:	Figure 2.13 Optimized V antenna: Z
Quadrature component of the E field	component of the Poynting vector

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