A Compact Log-Periodic Monopole Array installed on top of vehicle

摘要

One serious drawback of Log-Periodic Dipole Array (LPDA) to operate down toVHF frequencies is their large size and difficulty to install on the roof of a vehicle.This could be tackled by reducing the LPDA to a monopole array reducing in onedimension the antenna by half. However converting dipoles to monopoles with theaim to use the conductor surface of the ceiling of the vehicle is not a simpleprocess. Eliminating half of the LPDA dipoles changes the feeding mechanisms ofthe array. Several authors starting from mid 1960's proposed solutions which werenot successful. In this effort a new type of Log-Periodic Monopole Array (LPMA)was developed based on the structure proposed by James M. Buzbee.Several monopole geometries were tried in simulator. It is shown that the use of afull wavelength horizontal non-radiating structures allows the proper operation ofthe array. Theoretical simulation results as well as measurements will bepresented.