Takuya Kaneko

Development of Design Procedure for Compact Planar Ultra-Wideband (UWB) Bandpass Filters

We have reported a compact planar-type UWB bandpass filter with tightly coupled E-shaped electrodes by Y. Horii (2007). In this paper, a useful and practical design procedure for this filter is developed, and explained in details with full-wave simulations. In addition, the resulting model designed by the introduced procedure is demonstrated experimentally to confirm the theoretical predictions. Furthermore, the design procedure is applied to several models with different substrate parameters, and a super-compact filter is designed on the substrate with the relative permittivity of 10 and thickness of 0.5 mm, whose dimensions, 2.7 mm x 2.01 mm x 0.5 mm (filter body), correspond to 24.4 % size reduction from the initial model reported in Ref [1].

A wideband low-loss negative group delay circuit based on negative impedance converters

In general, negative group delay (NGD) is generated by using an abnormal phase response of either passive or active RLC resonators, and therefore, it suffers from unavoidable narrow bandwidth and large insertion loss. In contrast, we propose a new scheme to yield a wideband low-loss NGD based on negative impedance converter (NIC) technology.

Influence of transistor packages and circuit dimensions for accurate design of negative impedance converters

Negative impedance converters (NICs), which can produce negative capacitances or negative inductances, are quite attractive for their potential for developing a new type of circuits we have never designed so far. However, those circuits, composed of active devices such as transistors or operational amplifiers, can easily become unstable due to their non-linearity, undesired couplings and excessive loop gains. Therefore, accurate circuit design is strongly requested. This paper theoretically studies the influence of transistor packages and circuit dimensions on NIC circuits, in collaboration with a circuit simulator Ansys Designer and a full-wave EM simulator Ansys HFSS.

Experimental verification of ultra-wideband multi-layered CRLH transmission lines with bandwidth enhanced unit cells

This paper proposes an LTCC-based composite right/left-handed (CRLH) transmission line composed of bandwidth enhanced unit cells (UCs), which suppress the potential difference induced between the parallel-plates of the UC, leading to reduce undesired resonance. By adopting the proposed UC architecture, an original passband from 2.9 GHz to 13.7 GHz is largely enhanced from 2.5 GHz to 23.2 GHz. These theoretical results are verified experimentally by implementing the LTCC models. By utilizing this feature, phase engineering of the right-handed branch is demonstrated.

A compact Mobius ring bandpass filter embedded in low-temperature co-fired ceramics (LTCC) substrate

This paper newly proposes an LTCC-based Mobius ring bandpass filter, in which the Mobius ring is embedded in a microstrip line substrate so that the electromagnetic fields around a microstrip gap couple to the embedded Mobius ring smoothly. Simulated results indicate that a λ/4 resonance is occurred on the ring and the fields are confined within the Mobius ring. A prototype model is implemented by using an LTCC technology to confirm the theoretical predictions.

LTCC-based multi-layered UWB bandpass filter with broadside coupled E-shaped electrodes for significant size reduction and improvement of out-of-band response

This paper newly proposes a low-temperature co-fired ceramics (LTCC) based multi-layered UWB bandpass filter with broadside-coupled E-shaped electrodes. This super compact filter, with overall dimensions of 5.0 × 5.0 × 0.95 mm3, has a wide passband response from 3.26 GHz to 10.96 GHz in theory with convenient transmission zeros just below and above the passband. The theoretical results are experimental verified by implementing an prototype model by engaging in LTCC technology. To improve the out-of-band response, multi-stage filters are also demonstrated theoretically.

Compact LTCC-based Multilayer Ultrawideband(UWB) Bandpass Filter Composed of Broadside-Coupled E-shaped Electrodes

Ultra-wideband (UWB) wireless communication systems, utilizing a huge frequency range from 3.1 ㎓ to 10.6 ㎓, are one of the key technologies to meet tremendous demands for up-coming high-speed wireless data communications. The hardware of such systems requires to be made very compact and highly functional. In this paper, research history of our planar-type UWB band-pass filters composed of capacitively couped E-shaped electrodes is outlined first. After that, a super-compact multi-layered UWB bandpass filter is newly developed by using the E-shaped electrode architecture. The designed filter, with overall dimensions of 5.0 x 5.0 x 0.95 mm3, has a UWB passband from 3.3 ㎓ to 10.7 ㎓ in simulation (a fractional bandwidth of 106 %) and from 3.5 ㎓ to 10.7 ㎓ in experiment (a fractional bandwidth of 100%). In addition, the filter has attractive transmission zeros just below and above the passband, whose creation mechanism is studied theoretically. Also, useful design procedure is introduced for this filter.

Ultra-wideband (UWB) bandpass filter composed of periodically-installed metallic posts in a rectangular waveguide

In this paper, we propose a UWB bandpass filter composed of periodically-installed metallic posts in a rectangular waveguide, and study the basic behaviour both theoretically and experimentally. From the simulation, the wide passband from 5.95 GHz to 13.9 GHz and the well-suppressed out-of-passband were obtained, which results were verified experimentally. For the design of UWB response, we also study the important structural parameters of the filter.

A Compact Multi-Layered Ultra-Wideband (UWB) Bandpass Filter with a Built-In Band-Rejection Filter

This paper proposes a compact multi-layered ultra- wideband (UWB) bandpass filter including a built-in band- rejection filter, for preventing the UWB communications from interfering with already-existing wireless communication systems. The band-rejection response obtained can be controlled flexibly by changing a coupling capacitance to the closest parallel metal plate or to the ground enclosure. In the finite element analysis and equivalent circuit simulation, a UWB performance of around 90% relative bandwidth and a widely-controllable band-rejection response were obtained. Also, experimental results show good agreement with those theory. This compact filter, originally designed based on the heft-handed composite right-/left-handed (CRLH) transmission line theory [1, 2], has a perfectly-shielded structure, a moderate group delay and excellent out-of-passband characteristics.