DUAL-POLARIZED RADIATING ELEMENTS FOR BASE STATION ANTENNAS HAVING BUILT-IN STALK FILTERS THAT BLOCK COMMON MODE RADIATION PARASITICS

摘要

An antenna includes a radiator and a feed stalk electrically coupled by first and second feed paths to the radiator. The feed stalk includes a common-mode rejection filter, which has first and second ports electrically connected to the first and second feed paths, a first inductor electrically coupled to the first port and a second inductor electrically coupled to the second port. The common-mode rejection filter is configured so that a first impedance electrically coupled to the first port is equivalent to Z_1, and a second impedance electrically coupled to the second port is equivalent to Z₂, where: Z₁ = R₁ + jωL₁ + jωM(I₂/I₁); Z₂ = R₂ + jωL₂ + jωM(I₁/I₂); M ≈ L₁ ≈ L₂; R₁ and R₂ are the resistances of the first and second inductors; L₁ and L₂ are the inductances of the first and second inductors; M is a mutual inductance between the first and second inductors; I₁ and I₂ are the first and second currents into the first and second ports; and ω is the angular frequency of the first and second currents.