Electronically tunable microstrip bandstop filters using a varactor-loaded open ring resonator (VLORR)

Reconfigurable Coplanar Waveguide (CPW) and Half-Mode Substrate Integrated Waveguide (HMSIW) Band-Stop Filters Using a Varactor-Loaded Metamaterial-Inspired Open Resonator

“…The structures and equivalent circuit models of the proposed tunable CPW and HMSIW band-stop filters are shown in Figure 1 and Figure 2 , respectively. Both structures use a basic open ring resonator (ORR) [ 22 , 46 ] loaded with a varactor diode. This cell, called varactor-loaded open ring resonator (VLORR), is connected to a section of a CPW or HMSIW line.…”

“…The simplified equivalent circuits of the CPW and HMSIW structures loaded with a VLORR cell are depicted in Figure 1 b and Figure 2 c, respectively. They were obtained from previous electromagnetic (EM) analysis of their frequency responses, taking into account the initial simplified model of the ORR cell [ 22 , 46 ], with a variable capacitance , as the ideal model of a varactor diode. The ORR cell is modeled by means of a shunt series resonant circuit connected between two CPW sections or two HMSIW sections of length .…”

“…Band-stop filters integrating complementary split ring resonators (CSRRs) in the ground plane of microstrip structures have also been proposed [ 19 , 20 , 21 ]. A recent publication describes an example of tunability in microstrip technology [ 22 ]. However, in contrast to microstrip, there has been not so much published research on tunable coplanar waveguide (CPW) [ 9 , 23 , 24 , 25 , 26 , 27 ] and tunable substrate integrated waveguide (SIW) [ 28 , 29 , 30 ] band-stop filters using varactor diodes.…”