CONFIDENTIAL 16
페이지
2005-06-08
In case a patch antenna element is used the user must take into account a few factors
that affect antenna performance:
z
Size of patch element: smaller elements tend to give lower signal levels due to
reduced radiation efficiency.
z
Size of GND plane under the patch element: smaller than 70mm GND plane
reduces antenna directivity and signal levels.
z
Avoid unsymmetrical GND plane: polarization characteristics declines causing
polarization miss match loss (reduction in signal levels) and reduction in multi
path mitigation (navigation accuracy).
These all issues affect the radiation pattern and the resonance frequency of the
antenna. The antenna selection and design is a very critical issue and must be
reviewed case-by-case.
Note also that the enclosure material (e.g. plastic cover) also affect the resonance
frequency in such a way that plastic material close to the antenna element move the
resonance frequency downwards. This must be taken also into consideration when
specifying the antenna resonance frequency.
HPM103H-6
