A helical-shaped slot microstrip band pass filter based on SIW technology for WLAN and Bluetooth applications

A new compact wideband Substrate Integrated Waveguide (SIW) band pass filter utilizing of a helical-shaped slot is presented. This filter is consisting of four slots such that each one occupies a corner. Construction and evaluation of the proposed model have been done using the EM simulator of microwave studio suite from computer simulation technology (CST). The overall size of filter is 10 mm × 10 mm using a substrate with relative permittivity of 6 and height of 0.254 mm. This filter is designed to meet compact size, good return loss and low insertion loss. The obtained results exhibit a return loss below -40 dB and insertion loss approaching to 0 dB over the passband with a -3 dB fractional bandwidth of about 70% centered at 2.4 GHz. The simplicity gained with this structure led to freely control the position of the pass band through doing simple alterations of the helical-slots dimensions. As a result, this make the proposed filter candidate for operating in wireless applications like wireless local area network (WLAN) and Bluetooth applications.