This paper presents a dual band aperture coupled stacked microstrip antenna with the introduction of an air gap 3 mm between the ground plane and the upper layer substrate for WLAN applications. The nominal antenna has -10 dB return loss bandwidth of 134.8 MHz and 384.9 MHz at lower band resonant frequency of 3.905 GHz and upper band resonant frequency of 5.36 GHz respectively. The gain of the antenna is greater than 5 dB, also the directivity is greater than 5 dBi and VSWR value is less than 2 for both the operating frequencies, which makes it a suitable choice to be used at the frequencies bands of WLAN.

The aim of this paper to find best suited filter for given photo detector i.e APD and PIN for the suppression of noise in the proposed optical system. This paper also analysis the effect of SOA for noise reduction in the optical communication system. It is concluded that APD photodiode gives a better Performance in given optical system in comparison with PIN photodiode. Low pass Bessel filter shows the best performance among the other filters at 1310 nm wavelength. Bessel filter provides constant group delay. Eye opening height is more in Bessel filter. It gives minimum Bit error rate in received signal. Semiconductor optical amplifier reduces the noise in optical system. It improves the quality of received signal. It provides lower bit error rate upto 20 km optical fiber.