Low noise amplifier design for hidden wireless lan applications using band pass filter with geometric mean prototype element values

Abstract

Detection and perception problems may occur when the amplitude level of some signals that need to be received and detected is weak. Information that is requested to be kept confidential or not shared with other units is always available in the environment as wireless electromagnetic (EM) waves. Detection can only be made with the appropriate method. Thermal radiation emitted by objects that are intended to be hidden under clothing can also be given as an example. The signal level of these EM waves is very low. In this case, low noise amplifier (LNA) circuits are used to increase such values to a measurable level by network analyzer. In this study, a design with 17.19 dB gain for WLAN applications is made using BL011 LNA chip gathered from BeRex company with a 3rd order band pass filter (BPF) at 2.4 GHz center frequency, it has 200 MHz band width (BW) and 50 ohm characteristic impedance. An innovation has been introduced to design BPF as using the geometric mean prototype element values (PEV) by the help of geometric mean of 4 known techniques: Butterworth, Chebyshev (0.5 dB ripple), Bessel and Gauss (to 12 dB) normalized table values. According to the researches, the BPF circuit created by the geometric averaging method with the BL011 LNA chip has never been used to detect hidden EM signals in the WLAN band. Finally, the proposed BPF circuit is 2 in total, one at the input and one at the output; LNA circuit designed by using BL011 module and impedance matching circuit, a total of 3 consecutively connected and combined systems are formed. The proposed full system has the merits of compactness, good input reflection coefficient and good S21, gain characteristic.