Section VI: Measured Results for the New DGS
Fig.15- Ground Plane view of fabricated Bandpass/bandstop filter
Fig.16- Top Plane view of fabricated prototype
Fig. 17- Measured result showing the Passband and Stopband Frequencies.
The band-pass filter is designed in CST Microwave Studio and fabricated
on a Rogers 4350B substrate having \(\epsilon_{r}\)= 3.66, height of
1.52 mm and a loss tangent of 0.0037. The fabrication is shown in Fig.
15 and 16, which shows the top and the ground plane of the structure.
The 9 pF capacitor is soldered onto the gap in the DGS and the 3 pF
capacitor is mounted in the coupling gap in the 50 \(\Omega\) microstrip
line. Two SMA connectors with impedance 50 \(\Omega\) are also soldered
and the filter is measured using a Keysight N9926A handheld VNA.The
result for the fabricated structure, given in Fig. 17, clearly shows the
presence of a sharp band-stop and band-pass response. Similar to the
previous design, the work proposed is not immune to port, connector and
soldering losses. Moreover, the varying tolerance of the SMD again plays
a role in shifting of resonant frequencies. To avoid this, one can
fabricate multiple prototypes til the desired frequency is achieved.
Another route that can be explored is using capacitors with extremely
low tolerances.