The first resonance frequency f1 of the printed monopole
antenna is chosen to be of 2.45 GHz. The second
resonant frequency f2 is a multiple of the first resonant
frequency. Without the element of length L1, the radiating
element is found to be giving the second resonant frequency
at 5 GHz, whereas by including this L1 in the radiating
element, the second resonant frequency is obtained at
5.18 GHz. Thus this small length L1 is shifting the second
resonant frequency from 5 GHz to 5.18 GHz. By properly
varying the dimensions of the antenna, we can fix the antenna
resonance at 2.51 GHz and 5.18 GHz respectively.
The overall adjustments of the geometrical parameters are
done for the improvement of impedance bandwidth in the
2.45 GHz and 5.2 GHz band. The final optimized dimensions
of the antenna through EM simulations are L1=1 mm,
L2 = 5.4 mm, L3 = 10 mm, L4 = 7 mm, we = 3.06 mm,
Lk = 14 mm and Lgnd = 12 mm. The dimensions (WxL) of
the substrate are 30 mm and 38 mm respectively.