Variable Z
A variable Z 0 impedance method (“Variable Z 0 ”) for designing and/or optimizing antenna systems. The method provides that the value of an antenna's feed system characteristic impedance or apparatus internal impedance (Z 0 ) changes as a true variable quantity during the antenna system design or optimization methodology. The value is allowed to be determined by the methodology, because different values of Z 0 result in different antenna system performance. It is applied to any set of performance objectives on any antenna system wherein apparatus internal or transmission line characteristic impedance is an explicit or implicit parameter. Variable Z 0 is applied to any design or optimization methodology. Structures include Yagi-Uda arrays, Meander Monopoles, and transmission line Multi-Stub Matching Networks, and can incorporate Central Force Optimization or Biogeography Based Optimization or other optimization algorithms.
1. A method of designing an antenna connected to a feed system including a radio frequency source, the method comprising:
choosing minimum and maximum feed system characteristic impedance values;
using an iterative antenna design algorithm on a computer where antenna design parameters and a feed system characteristic impedance value are variables to achieve one or more antenna performance objectives;
varying said antenna design parameters while varying feed system characteristic impedance values between the minimum and maximum feed system characteristic impedance values until said one or more antenna performance objectives are achieved using said iterative antenna design algorithm;
determining a feed system characteristic impedance value from the varied feed system characteristic impedance values which results in said one or more antenna performance objectives;
designing the feed system such that said feed system exhibits said determined feed system characteristic impedance value or an approximation of said feed system characteristic impedance value;
determining which antenna design parameters result in said antenna performance objectives; and
designing the antenna according to said determined antenna design parameters to achieve said one or more antenna performance objectives.
2. The method of claim 1 in which said antenna design parameters include antenna element length, diameter, and/or spacing; and/or helix diameter, turn pitch, wire gauge, and/or the number of turns.
3. The method of claim 1 in which varying the antenna design parameters include varying the antenna design parameters between maximum and minimum values.
4. The method of claim 1 in which said one or more antenna performance objects are input into the iterative antenna design algorithm.
5. The method of claim 1 in which said iterative antenna design algorithm includes Central Force Optimization, Dominating Cone Line Search, Particle Swarm Optimization, a Genetic Algorithm, Ant Colony Optimization, and/or Differential Evolution.
6. The method of claim 1 in which the feed system further includes a transmission line and/or a matching network and designing the feed system includes choosing a transmission line and/or matching network such that the feed system exhibits said determined feed system characteristic impedance value.
7. The method of claim 1 in which said antenna performance objectives include voltage standing wave ratio, gain, and/or Front-to-Back ratio.
8. The method of claim 1 in which the determined feed system characteristic impedance value is within a factor of three of a standard fixed antenna feed system characteristic impedance value.