Cost optimization of HPM systems

For fixed power density in the far field, what is the cost-optimum HPM system? We derive general relations for cost-optimal aperture and power. For linear dependence of capital cost on transmitter power and antenna area, minimum capital cost occurs when the cost is equally divided between antenna gain and radiated power. For non-linear power law dependence a similar simple division occurs. This is validated in cost data for many systems and is used as a rule-of-thumb in industry. Cost of pulsed cost-efficient transmitters can be estimated using these relations using current cost parameters ($/W, $/m²) as a basis.