Although the aperture coupled patch is more difficult to design and manufacture, it has a number of advantages over patches with simpler feed-methods. It provides better operational bandwidth, is well suited to direct integration with microstrip circuits and reduces the effects of feed-network radiation when used in an array configuration.
The main advantages of this antenna revolve around the separation between the feed network (on the underside of the bottom substrate) and the radiating element on the top substrate. For some applications, active components (like phase shifters and amplifiers) can been integrated on the bottom substrate.
In Antenna Magus this antenna can be designed for specific bandwidth. The achievable bandwidth is mainly dependant on the thickness of the substrates used. This is illustrated in the following S11 graph image. ...Typical S11 for thick and thin substrates.