mixer for more than 5 GHz

This is a diode single-balanced mixer using a 180° hybrid, and its layout.
At the output is used a notch-filter to reject the LO and a 60MHz cut-off LPF to reject the RF and LO and allow just the IF to pass through.

And what is thes A, B, C, D forms?

Microstrip lines with W and L values respectively
I don't know the substrate type..