8(a)) and the fibre matrix of the FR4
And when filled with FR4
it operates at dual frequencies 3.25 and 4.84GHz with return loss -19.9307 and -11.8844dB respectively
In the case of FR4
, FR8 and FR8 energy was dissipated due to gradual development of damages in frame joints and by friction along the frame-to-glass contact.
Reference Substrate Patch Bandwidth (MHz) material area ([mm.sup.2])  FR4
25x 25 300, 500, 700  FR4
23 x 30 290, 290, 700  FR4
40 x 50 180, 150, 170 Proposed FR4
20 x 20 360, 440, 1550 Reference Max gain (dBi) Applications  2.15, 2.47, 4.13 WiMAX/WLAN  2.29, 0.9, 3.45 WiFi/WiMAX/C-band  1.7, 2.3, 4.1 Tri-band wireless Proposed 3.62, 3.67, 5.7 WiMAX/C-band
This study has been performed first by taking RT duroid as substrate and then FR4
board was replaced by air to simplify the simulation model.
7, the frequency from 0 to 32 GHz is a near-field measurement under a fixed distance of 0.7 mm and a loop length of 1.8 mm in the FR4
In order to demonstrate the effectiveness of applying uniform microstrip asymmetrical coupled lines instead of isolated coupled lines in multi-section Wilkinson power divider for elimination the narrow strip widths, a sample of the power divider with 1 : 2.5 power division and bandwidth of 96% is designed with the FR4
substrate with a thickness of 1.57 mm and approximate dielectric constant equal to 4.47 Furthermore, the designed power divider has three sections and the coupling coefficients are [c.sub.1] = 0.377, [c.sub.2] = 0.268 and [c.sub.3] = 0.165.
Each of the SAR values presented in the following tables (3-6), consists of three different antenna substrates, namely FR4
, Rogers RO3006 (loss free), and Rogers RO4003 (loss free) with variations of dielectric properties of head.
The radiating patch and the L-shaped feeding strip are printed on two pieces of FR4
substrates and the substrates are supported by plastic posts which have little influence on antenna's performance.