*2.1.4 Improvement of the filter response by dual DGS units*

The filtering response of the filter can be improved to higher-order by simply adding another hexagonal head DGS structure of the same dimension side by side with the previous one. The single hexagonal DGS unit provides poor selectivity (11.6 dB/GHz) and small 20 dB rejection bandwidth (360 MHz). Therefore to obtain a good transition between passband and stopband and broader stopband, an array of DGS structures can be used with high and low impedance microstrip lines [14]. The High-low line decreases the insertion loss and provides better matching in the input. Therefore, the main objective is to design an LPF implementing two hexagonal dumbbells DGS units. The schematic diagram of the filter is shown in **Figure 8**. The arm length of the hexagonal head dimension of the individual unit is *a* = 2 mm with a separation of L = 2 mm. The transverse slot dimension of each unit *g* = 0.2 mm, etched out under the compensated transmission line of width, *W*<sup>1</sup> = 5 mm. The transverse slot length, *b* = 3.8 mm.
