On the Crosstalks between a Pair of Transmission Lines in the Presence of a 3D Printed Electrifi Trace

The technology of additive manufacturing results in 3D printing of conductive traces in radio frequency circuits. This creates a plethora of possibilities in realizing flexible and wearable electronics. While the prototypes of microstrip transmission lines and antennas have been recently reported, there is now a need of Electromagnetic Compatibility based study of such 3D printed conductive traces. This paper presents a comparative study on the near end and far end unintentional crosstalk components between a pair of microstrip transmission lines made of Copper in the presence of a 3D printed conductive trace made of a commercially available conductive filament, Electrifi. Any physical contact with the 3D printed trace has been purposefully averted to discard the high contact resistance between the trace and such contacts.

Novel Platform for Droplet Detection and Size Measurement Using Microstrip Transmission Lines

We propose a novel platform for detecting as well as measuring the size of individual droplets in microfluidic channels using microstrip transmission lines. The most outstanding feature of our platform is that, as opposed to previous related works, its design allows for the droplet to flow in a microfluidic channel fabricated between the top strip and the ground plane of a microstrip transmission line. This provides enhanced interaction of the electromagnetic field with the detected droplets. The proposed design allows us to measure droplet size directly from the phase of the microwave signal, without the need for a resonator. The platform is based on low temperature co-fired ceramic (LTCC), which makes it more compatible with Radiofrequency (RF) and microwave technology than platforms used in previous works. With this platform, we are able to measure droplets as small as 150 µm in radius. It is worth pointing out that our device could also be used for detection, counting and measurement of other microscopic objects.

Compact Microwave Components with Harmonic Suppression Based on Artificial Transmission Lines

In this paper, compact microwave components, including a Wilkinson power divider and a 3 dB branch-line coupler based on artificial transmission lines (ATLs) with harmonic suppression, are presented. A section ATL is consisted of microstrip stepped impedance transmission lines and a microstrip interdigital capacitor. To achieve a compact size, the stepped impedance transmission lines are folded into a right-angled triangle shape. For the ATL, the interdigital capacitor is used to suppress harmonics. By employing two sections of 70.7 Ω ATLs with a right-angled triangle shape to replace conventional transmission lines, the proposed power divider working at 0.9 GHz achieves a size miniaturization with the 58.8% area of a conventional case. In addition, the power divider has good harmonic suppression performance. In the design of a branch-line coupler, two pairs of ATLs with 50 Ω and 35.4 Ω are utilized. For 50 Ω ATLs, the ATLs are designed to a right-angled triangle shape. Meanwhile, to obtain a more compact size, these 35.4 Ω ATLs are modified to an isosceles trapezoid shape. The proposed branch-line coupler operating at 0.9 GHz accounts for merely 33.4% of a coupler adopting conventional microstrip transmission lines. Moreover, the harmonics of a branch-line coupler are suppressed effectively as well. Finally, measured results of the proposed Wilkinson power divider and branch-line coupler display good performance and agree with their simulated results well.