I have an EBG structure which resonates at 2.3GHz and 4.8 GHz. But I need to change the frequency of resonation to 7.5GHz. I achieved 7.2GHz resonation with an S11 of -10dB and S21 at -3dB (this was done by changing port size and dieletrics). Is there any way to fine tune the structure to achieve 7.5GHz resonating frequency. I read that changing interdigital capacitance helps. Any one has an idea how the unit cell size will effect the frequency of operation and how it effects.
Aswin Sankar P D , changing port size is probably not relevant here -- you want to make sure you have the most realistic excitation.
In general, narrowband resonator EBGs support a primary stopband near their quarter-wavelength frequency. So, if you want to increase the frequency of this region, simply reducing the periodicity should help (usually, this frequency is proportional to the period).
The frequency of operation will scale directly inversely with the scale. If you keep the same proportions of height, width and depth in your shape, the wavelength of operation is proportional to the length of the unit cell. The only thing that doesn't scale properly is conductivity, so losses will probably increase with smaller unit cells.
As the unit cell size decreases, the frequency of the bandgap increases. This is because as the size of the unit cell is reduced, the dimensions of the metallic and dielectric elements also decrease, which leads to a decrease in the wavelength of the band gap. Moreover, as the unit cell size decreases, the coupling between adjacent unit cells becomes stronger, which can also increase the frequency of the bandgap.
According to my experience in Antenna design, the length of the substrate, including the length of the ground plane have implications in the resonance frequency. For instance, by increasing these length shifts the resonant frequencies toward the left (decrease) while reducing the lengths moves the resonance toward the right side (increase). You can read my article through this link.
Article A miniaturized dual-band planar antenna with a square ring d...
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