Design of Various Compact Branch-Line Couplers by Using Artificial Transmission Lines

Abstract

In this paper, a compact and easy to fabricate brach-line couplers, which can be used for tight and weak couplings with high directivity, is proposed. For these purpose, various artificial transmission lines (ATLs) are incorporated. Design of 3 dB and 10 dB couplers are designed and their characteristics are measured. Good electrical performance and circuit miniaturization indicate the validity of the present theory.

Artificial Transmission Lines

“…Other approaches to achieve slow-wave transmission lines are based on increasing not only the line capacitance but also the line inductance (12)(13)(14). Compact lines based on multiple stubs loading in an iterative scheme have been also reported (15). Miniature artificial transmission lines in multilayered structures have been proposed in References 16-18.…”

“…However, for open lines, such as microstrip or CPW transmission lines, where pure TEM wave propagation is not possible, the previous expression does not hold. However, the phase velocity in open lines can be expressed as Equation15 by simply replacing the dielectric constant of the substrate material, ε r , with an effective dielectric constant, ε re , which takes into account the presence of the electric field lines in both the substrate material and the air:…”

A Miniaturized Branch‐Line Coupler Using Triangular Patch Type Artificial Transmission Line

“…On the other hand, the rapid development of the recent wireless communication systems highly demands the miniaturized and integrated microwave components [5,6], and many miniaturization methods have been reported [2][3][4][5][6][7][8][9][10]. One of the most sophisticated methods among them is the design method of microwave circuit elements using the artificial transmission lines (ATLs), which are various nonuniform shaped transmission lines that can equivalently accomplish arbitrary electrical lengths and characteristic impedances of the conventional transmission lines [5][6][7][8][9][10].…”

“…Recently, UWB technology has been applied for various applications due to its advantages such as low cost, low power consumption, precise localization, and high penetration. Local and personal area networks, military communications, vehicular radar [1], ground-penetrating radar [2], through wall imaging [3][4][5], medical imaging [6][7][8], and precision locations systems [9] are good examples of such applications.…”