Design and Structure of Antenna Systems
Different types of MIMO antenna systems have been proposed for UWB applications. The designed
systems show good impedance characteristics in the frequency band of 3.1-10.6 GHz,
thus fulfilling the FCC requirements for UWB communications. These systems also have very
low mutual coupling and correlations, so they provide good diversity performance. These MIMO
antennas are composed of either identical stepped patch or identical circular disc monopole
elements. Both planar UWB antennas fed by 50 O microstrip line i.e. stepped patch and circular
disc monopole have already presented in [12] and [13] respectively. The selection of these antennas
to design MIMO antennas can be justified by their good performance, size and ease of
integration. However, these antennas have been redesigned to adapt the changes in substrate
and thereafter optimized to reduce their dimension as compared with those presented in [12]
and [13]. First of all, in [14], a compact antenna system comprising two identical stepped patch
elements has been proposed as shown in Fig. 1. The dimensions of the antenna system are: W =
68 mm, L = 30 mm and d = 8 mm. The stepped patch elements have been integrated on a single
substrate (1.6 mm thick) orthogonally with respect to each other. This geometrical configuration
is well justified by comparing with 0 degree and 180 degree positions of two antenna elements
on the basis of S-parameters.
W