Hi,
When working with paralell (edge) transmission line coupled filters, the first and the last resonator usually require a very small coupling gap to input and output lines. This might couse technological problems. In order to avoid this, input and outputs are connected directly to a first resonator at some "tapped" position along the line. This is just to give you a hint what it is all about, you can read more in the book by Hong - Microstrip filters for RF microwave application, it can be downloaded on this site.
flyhigh