Achievement of frequency invariant radiation pattern by a wide band array antenna fed by log periodic dipole antennas

摘要

In software defined radios, wide hand antennas are requested. Authors developed a wide band array antenna configuration. Frequency invariant radiation patterns in 2 GHz to 10 GHz were ensured though calculation of array factors. Here in order to clarify the realizability of wide band radiation patterns, an actual antenna configuration is studied. As radiation elements of the array antenna, log periodic dipole antennas(LPDA) are employed. First, suitable antenna parameters of LPDA are discussed. Next, a wide band array antenna configuration is determined. Calculated results show frequency invariant radiation patterns in 2 GHz to 10 GHz band. Moreover, current distributions on LPDA are investigated. A study of improving radiation pattern is also made in 2 GHz band. In order to investigate mutual couplings in 2 GHz, performances of a dipole antenna fed array antenna are studied. Current distributions on radiation elements which are important to achieve radiation patterns are not affected by mutual coupling. In the case of a LPDA fed array antenna, current distributions on all the elements are not affected by mutual coupling. Situations of achieving frequency invariant radiation patterns are clarified.