A Novel Transition From Substrate Integrated Suspended Line to Conductor Backed CPW

Abstract

A novel transition from substrate integrated suspended line (SISL) to conductor backed coplanar waveguide (CBCPW) is proposed in this letter. The proposed transition utilizing the standard PCB techniques eliminates the drawbacks of the traditional suspended circuits and integrates the suspended circuits effectively. The new transition is a self-packaged system verified by both simulation and experiment results. Back-to-back transition structure has insertion loss of less than 0.6 dB and return loss of better than 15 dB from dc to 8 GHz.Index Terms-Conductor backed coplanar waveguide (CBCPW), printed circuit board (PCB), substrate integrated suspended line (SISL), transition.

Loss mechanism of the SISL and the experimental verifications

“…The first case is the single-layer case, the second one is the double-layer case with via hole connection, and the third case the double-layer structure with the patterned substrate. A transition [15] from the tested SISL inside to connectors outside is used. Fig.…”

“…The commonly used transmission lines contain microstripe [1], coplanar waveguide (CPW) [2], stripline [3], metallic waveguide [4], substrate integrated waveguide [5], and so on. Recently, a new platform named substrate integrated suspended line (SISL) [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] has been proposed, and it features good properties like low loss, selfpackaging, low cost, and high integration. The SISL concept is inspired by the conventional waveguide suspended line, and it embeds air cavities inside multi-layer boards.…”

“…The electric boundary of SISL is constituted by the top and bottom metal layers and the plated through holes or via holes around the air cavity, which is different from the continuous boundary in the convention waveguide suspended line. The SISL platform has been applied in various designs, including SISL-based couplers [7][8][9][10], filter [11], balun [12], Magic-T [13], Butler matrix [14], transitions [15,16], antenna [17], and other designs [18][19][20] with good performance.…”

Synthesis of Absorption Reflectionless Bandstop Filter and Its Design Using Multi-Layer Self-Packaged SCPW

“…The input/output ports are using conductor-backed coplanar waveguide (CBCPW) with a characteristic impedance of 50 Ω , and there is a transition between CBCPW and the suspended CPW. Suspended stripline offers wider strip widths with the same characteristic impedance compared with the microstrip/stripline, and the majority of the electromagnetic field distributes in air rather than in substrate dielectric layer, which results in a reduced loss and dispersion, and the circuit quality factor is enhanced [11] [12]. However, the traditional suspended stripline requires metal housing and additional mechanical process, which introduce increased circuit size and weight.…”

Design of Wideband Microstrip to SICL Transition for Millimeter-Wave Applications

“…In [3], planar counterpart of waveguide has been extensively utilized to develop various microwave circuits and antennas. A novel methodology to interconnect substrate integrated suspended line with coplanar waveguide is shown in [4]. A newer technology to synthesize the traditional coaxial line in planar form was devised in [5], namely substrate integrate coaxial line (SICL).…”