A Compact Filtering Coupler with Unwanted Harmonic Rejection Using LC Composite Lines for Communication Systems Applications

In this paper, new LC lumped components and composite lines are used to create a filtering branch line coupler (FBLC) with small size wide suppression band. New proposed using applied components, which as the main branches. The FBLC suppresses second sixth harmonics high attention level provides stopband from 1.6 GHz 5 more than 20 dB of attention. presented is analyzed, designed, simulated, implemented. measured results show that correctly operates at 800 MHz less 0.25 insertion loss. addition, 29 return loss isolation operating frequency, shows correct performance design. equal 23.7 mm × 25.5 (0.086? 0.093?), an 87% reduction. designed frequency can be in communication systems for narrow-band Internet things (NB-IoT) traffic control radar applications.