A novel compact branch‐line coupler using four coupled transmission lines

Abstract

After analyzing MDA current distributions, it is observed that those along the meander parallel conductors basically do not exhibit a 180°diphase. Furthermore, MDA collinear elements can be described as transmission lines with variable characteristic impedance. Thus, a full TLM reformulation can be performed to model the voltage at MDA feed and calculate its resonant frequency. The equation provided involves all the geometrical antenna parameters. Therefore, either a synthesis of a MDA from its resonance frequency or MDA analysis for resonance estimation can be performed. The relative error falls below 7.8% in the prototypes under study. The MDA resonant frequency reduction factor can be estimated from the model mainly by the number of meanders without the need for simulations. It is demonstrated that further predictable antenna tuning can be achieved either by meander dimension adjusting or by meander drifting along the MDA, which cannot be explained by other models in the literature. Furthermore, the model shows that meanders closer to antenna edges are more size-reduction efficient than those closer to the antenna feed. Therefore, it makes MDA be more easily matched to compact and low profile application circuits.

A Novel Miniaturized Branch-Line Coupler With Equivalent Transmission Lines

“…Figure 3 shows the equivalent circuit of a single transmission line with dual transmission lines. In this paper, to reduce the BLC's size, the usual quarter wavelength lines in conventional BLC are replaced by the proposed compact model of dual transmission lines [8].…”

Realization of a Highly Miniaturized Elliptic-Function Band-Pass Filter Using Microstrip Quasi Multi- Mode Resonator for Wide-Band Applications

“…The use of connected lines as a cascaded two unit elements instead of internal series stubs is a useful method to increase the bandwidth in interdigital elliptic filters [13,14] which is also considered in this paper to design a compact BPF with a wide-band pass-band. In this paper, a novel arrangement of triple coupled transmission lines is proposed to design a highly compact band-pass filter with a wide pass-band.…”

Realization of a Compact Branch-Line Coupler Using Quasi-Fractal Loaded Coupled Transmission-Lines

“…Recently we introduced a compact model of a quarter-wavelength transmission-line using a loaded coupled transmission-line [8,9]. It has been shown in [8] that the use of a cascade of two coupled transmissions-lines provides an effective technique to compensate for the bandwidth reduction resulting from size reduction using previously reported techniques.…”

“…It has been shown in [8] that the use of a cascade of two coupled transmissions-lines provides an effective technique to compensate for the bandwidth reduction resulting from size reduction using previously reported techniques. This model was used to miniaturize a conventional branch-line coupler by a factor of 65% without compromising its operational bandwidth.…”

“…In this paper, a novel loaded coupled transmission-line based on [8] is used to realize a highly compact model representing a quarterwavelength transmission-line by applying a quasi-fractal technique. This technique is used to create extra cascaded coupled transmissionslines within the main coupled transmission-line model.…”