A fundamental characteristic of the proposed solution is that the whole 4x4 matrix is physically realized as a single LTCC board having a size of about 8x8 cm. The possibility to route and to cross the connection paths by using up to 14 inner layers of the LTCC improves either the Isolation among the connections paths or their RF radiation that may increase the losses and generate undesired couplings, which, in turns, would impact the Isolation as well. Useful features of the LTCC technology developed in TASI, such as losses compensation over the routes and Via fences for signal isolation, allow to optimized the main electrical performances, such as Gain and Isolation between different channels.
Two custom MMICs are developed to physically switch signals trough the different channels. A reflective SP4T ensures that just one Input can be routed to one Out. At the Input section, the standard SP4T is replaced by a “re-configurable” SPDT capable to route the Input signals from 1 up to 4 Output at the same time. This feature, Point-to-Multipoint, gives to the switch matrix user the possibility to manage variation in the traffic, in case there is the need to allocate more resources (active transponders) onto one particular beam.
The baseline architecture is based on the Clos network making use of 4x4 blocks, made again by using a Clos blocks, where each Input can be connected to all Outputs satisfying the Non-Blocking requirement and allowing, at the same time, the Point-to-Multipoint configuration (Figure 1).
A proper packaging of the Building Blocks allows to realize the 32x32 matrix, by a combination of 40 of them, with a very compact layout (Figure 2)