Hi aboozar,
I think this is the best article available as of now...
**broken link removed**
Simple PBG Structures Serve Microwave Designs
Photonic bandgap structures offer the potential of low-cost fabrication and good bandstop characteristics for a variety of active and passive microwave circuits.
The top part of Fig. 3 shows the layout of the designed PBG structure with a 50-Ω microstrip line placed at the center position above the periodic 8 × 8-mm square holes with periodic distances of D = 2W along the ground plane. The middle section of Fig. 3 shows the 50-Ω microstrip line placed around the center position of the ground plane above the periodic holes. To take this design approach one step further, the 50-Ω microstrip line was moved to the fringe wall of the perforated square edge (bottom part of Fig. 3). Results of the EM simulations for S21 responses are shown in Fig. 3.
where:
d = the height of the dielectric substrate, and
W = the width of the microstrip line.
f = the frequency of the stopband width with a number holes,
c = the speed of light, and
D = the distance between the periodic holes on the ground plane