Tx antenna in free space Far field:(r>>r>>D,antenna's dimension) (Spherical wave) r.0.p)=E(0p7 vectorial amplitude propagation B= 2元 E。⊥T factor E Complex vector or phasor,so that e(r.0.p.t)-RefE(r.0.p)e]Tx antenna in free space ? Far field: ( r >> λ r >> D , antenna’s dimension) Tx (Spherical wave)  E(r,θ,ϕ) ≈  Eo (θ,ϕ) e− jβr r vectorial amplitude  e (r,θ,ϕ,t) = ℜe  E(r,θ,ϕ)ejωt { }  E Complex vector or phasor, so that propagation factor β = 2π E λ o ⊥ r r