Electrically Small Antenna Design
Electrically Small Antenna Design
Outline Definition and limitations of electrically small antenna (ESA) —byL.J.CHU Metamaterial-based efficient ESA(Simulation) -by Richard W.Ziolkowski's group Metamaterial-inspired efficient ESA (Application) -by Richard W.Ziolkowski's group Other groups'work
Outline Definition and limitations of electrically small antenna (ESA) ——by L.J.CHU Metamaterial-based efficient ESA (Simulation) ——by Richard W. Ziolkowski’s group Metamaterial-inspired efficient ESA (Application) ——by Richard W. Ziolkowski’s group Other groups’ work
Definition and limitations of ESA
Definition and limitations of ESA
Definition of electrically small antenna Fields of a short,linear electric-current element 1 E= sine e-jkr 7w6 -1 13 kr3 1 Er=-2c080 e-jkr +) 1 2-j Ze Ea=Z。}+1 kr =Re-iX for TM wave kr + IX ”-ky+ER+forTE wave IRI () We often use koa 1 as the standard for ESA
2 0 2 4 3 0 2 2 2 2 2 1 ( ) for TM wave ( ) 1 for TE wave 1 ( ) e e e m m m kr j E kr Z Z R jX H kr k k j E r Z Z R jX H k k r r 3 | | 1 | | ( ) X R kr Definition of electrically small antenna We often use as the standard fo 0 1 k a r ESA Fields of a short, linear electric-current element
An example-Traditional method for size reduction e=/VB,≈/2，ka=π Using high permittivity dielectric 2。/2,ka=π/2 Using short Short edge Short edge 2./4,ka=π/4 ↓ Short edge Using symmetry 。/6≈/12，ka=π/6 Short edge Using meandering
An example—Traditional method for size reduction Short edge Short edge 0 0 0 / / 2, g r k a 0 / 2, / 2 g k a 0 / 4, / 4 g k a 0 0 / 6 /12, / 6 g k a Using high permittivity dielectric Using short Using symmetry Using meandering Short edge Short edge