LOW INTERMODULATION ELECTROMAGNETIC FEED CELLULAR ANTENNAS

摘要

A dipole array antenna is configured for improved cellular operation by avoidance of metallic contacts which can lead to generation of intermodulation products (IMP). Isolated rectangular dipole radiators (12-17) are electromagnetically excited by perpendicularly aligned non-contacting exciter resonators (40-45). The rectangular exciter resonators (40-45) are integrally formed with microstrip signal distribution feed (18) supported above a ground plane (22). A non-contact RF grounded termination for the outer conductor of coaxial input line (52) uses a quarter-wave microstrip line section (56) to provide a low impedance RF path to ground to avoid IMP. An RF-isolated DC grounding circuit for surge protection includes a parallel combination of quarter-wave line sections (62 and 66). Line section (66) provides an RF open circuit path to a DC grounding post (67). Line section (62) provides a parallel non-contact low impedance RF path to ground, avoiding IMP from flow of an RF current through pressure contact points at post (67). The low impedance RF path to ground through line section (62) is isolated from the signal distribution line (18b) of the antenna by the RF open circuit provided by quarter-wave line section (68).