Considering wireless or radar applications, the idea of
integrating the antenna within the module is quite appealing:
the integration of the antenna on the top side of the module as
shown in Fig. 15 makes the antenna connector obsolete and
minimizes the feeding line length, thus reducing feeding losses.
Yet, due to the high dielectric constant ( ε r ≈ 7 ) of the LTCC
material, the design of a broadband planar antenna array is
quiet challenging because the bandwidth decreases with the
dielectric constant. However, LTCC materials are ideally
suited for multilayer structures. Therefore the characteristic can
be exploited by using stacked patch elements, thus
considerably enhancing the bandwidth. The antenna design
presented here is based on this principle.