*2.1.8 Measured results*

The proposed structure is fabricated and measured by Vector Network Analyzer (VNA). The critical dimensions of the fabricated structure are *a* = 2 mm, *b* = 3.8 mm, *g* = 0.2 mm, *W* = 1.92 mm, *W*<sup>1</sup> = 5.6 mm, *W*<sup>2</sup> = 11.8 mm, L = 2 mm. i.e., same as that of the simulation procedure. The photographic view of the structure is given in **Figure 12**. The comparison of the measured and simulated responses is shown in **Figure 13**.

The measurement result provides cutoff frequency = 2.6 GHz, Pole frequency = 3.06 GHz, insertion loss = 0.7 dB, 20 dB stop-band = 6.48 GHz, sharpness factor = 60.7 dB/GHz. The measured phase response is given in **Figure 14**. The discrepancy between measured and simulated phase responses is mainly due to the error resulting

**Figure 11.** *Simulated S- parameter Response of three DGS units.*

**Figure 12.** *Photographic view array of three DGS units.*

**Figure 13.** *Comparison of the Simulated and measured s-parameter responses of an array of three hexagonal-head DGS units.*

from manual calibration for measuring the phase. So it can be concluded that the present structure provides less insertion loss and better transition between passband and stopband compared to the array of two DGS structures. **Table 3** establishes a comparative study as given below. Thus, from this table, it is clear that the array with higher numbers of DGS units provides a more acceptable response than the array with lower numbers of DGS units. So it can be concluded that, although the big array of DGS units increases the circuit size and complexity, it delivers better filtering performance. **Figure 15** shows a graphical representation of the comparison of the transmission coefficients (S21) performances of the single, dual and triple unit hexagonal head DGSs. Thus, from this table, it is clear that the array with higher numbers of DGS units provides a more acceptable response than the array with lower numbers of DGS units. So it can be concluded that, although the big array

**Figure 14.** *Comparison of simulated and measured phase responses.*

**Figure 15.** *Comparison of the S-parameters of a single unit, double units, and triple units hexagonal DGSs.*

of DGS units increases the circuit size and complexity, it delivers better filtering performance.
