The tri-section stepped impedance selleck chem concept is used to implement the desired BSF [5]. The proposed TBBSF has a total size reduction of approximately 82% and 67% compared with the conventional designs [2] and [3], respectively. This filter can be used to suppress the central resonant frequency (f0) by more than 25dB in the stop bands and simultaneously achieve a wide stop band with a fractional bandwidth of 46.28%, 16.22%, and 8.05% for the first, second and third frequency bands, respectively. A comparative analysis between the symmetric and asymmetric TBBSF with respect to fractional bandwidth, loaded quality factor, and external quality factor is presented and verified with the necessary relevant figures and analysis.2.

Design and Theoretical AnalysisThe proposed triple-band BSF is designed using a tri-section meandered-line open-end SIR with the length of each section being equal to 0.16, 0.15, and 0.83 times the guided wavelength (��g) [6]. The schematic of the proposed symmetric triple-band BSF is shown in Figure 1. The meandered-line SIR is placed on the upper half of the planar transmission line to form an asymmetric BSF. We analyze the asymmetric BSF to compare it with a system requiring a relatively low bandwidth, a simple structure, and a higher quality factor than the symmetric BSF. However, for final verification of the design, we fabricated a symmetric-type TBBSF. To analyze the change in the fractional bandwidth (FBW) and quality factor between the symmetric and asymmetric structure, we perform a simulation analysis of the asymmetric TBBSF.

Both of the structures generate a triple-band response with good selectivity and the same resonant frequency. The rectangular meandered line with different width is used to achieve the step impedance and placed symmetrically on either side of a 50? planar microstrip transmission line with a folding coupling gap of G. The proposed structure is designed on a Teflon substrate with a thickness of 0.504mm and a dielectric constant of 2.52.Figure 1Design layouts of the two proposed TBBSFs: (a) symmetric, (b) asymmetric.2.1. Generalized Triple-Band Tri-Section Stepped Impedance ResonatorA TBBSF is formed by cascading 0.16��g�C0.15��g�C0.83��g SIRs to obtain a deeper skirt performance with triple-band bandstop characteristics. The SIR is comprised of low impedance Z1 section with electrical length of ��1 followed by high impedance Z2 section with electrical length of ��2 and Carfilzomib a impedance Z3 section with electrical length of ��3. Figure 2 shows the configuration of the tri-section meandered-line SIR (TSMSIR) with input characteristic impedance ZTSMSIR [7�C11]. The filter resonates at three different frequencies and can be used in the design of a TBBSF.