A novel half mode waveguide based ferrite isolator design is presented in this work. For the first time, tunability of the isolation band is demonstrated for a ferrite isolator. Instead of using the conventional antisymmetric bias the isolator requires a single direction of the magnetic bias field due to the half mode operation. Yttrium Iron Garnet (YIG) is used as the substrate for the device. The metallic walls of the waveguide are realized using inkjet printing. The magnetic biasing applied to the waveguide causes the RF waves to experience negative permeability in one direction of propagation hence providing isolation for this direction. For an applied bias of 3000 Oe, the device provides a maximum isolation figure of merit of 76.7 dB at 7.5 GHz. The isolation band can be controlled by changing the applied magnetostatic bias. As the bias is varied from 1500 Oe to 3500 Oe the center frequency of the isolation band varies from 4.45 GHz to 9 GHz. The measured response of the isolator shows that it can be integrated in any RF system requiring lower cost and good isolation.

This paper presents an extremely low cost, tube conformable, printed T-resonator based microwave level sensor, whose resonance frequency shifts by changing the level of fluids inside the tube. Printed T-resonator forms the frequency selective element of the tunable oscillator. Unlike typical band-pass resonators, T-resonator has a band-notch characteristics because of which it has been integrated with an unstable amplifying unit having negative resistance in the desired frequency range. Magnitude and phase of input reflection coefficient of the transistor has been optimized over the desired frequency range. Phase flattening technique has been introduced to maximize the frequency shift of the oscillator. With the help of this technique, we were able to enhance the percentage tuning of the oscillator manifolds which resulted into a level sensor with higher sensitivity. The interface level of fluids (oil and water in our case) causes a relative change in oscillation frequency by more than 50% compared to maximum frequency shift of 8% reported earlier with dielectric tunable oscillators.

This paper presents a novel and contactless water fraction (also known as water cut) measurement technique, which is independent of geometric distribution of oil and water inside the pipe. The sensor is based upon a modified dual helical stub resonators implemented directly on the pipe's outer surface and whose resonance frequency decreases by increasing the water content in oil. The E-fields have been made to rotate and distribute well inside the pipe, despite having narrow and curved ground plane. It makes the sensor's reading dependent only on the water fraction and not on the mixture distribution inside the pipe. That is why, the presented design does not require any flow conditioner to homogenize the oil/water mixture unlike many commercial WC sensors. The presented sensor has been realized by using extremely low cost methods of screen-printing and reusable 3D printed mask. Complete characterization of the proposed WC sensor, both in horizontal and vertical orientations, has been carried out in an industrial flow loop. Excellent repeatability of the sensor's response has been observed under different flow conditions. The measured performance results of the sensor show full range accuracy of ±2-3% while tested under random orientations and wide range of flow rates.

We propose a disposable, miniaturized, moveable, fully integrated 3D inkjet-printed wireless sensor node for large area environmental monitoring applications. As a proof of concept, we show the wireless sensing of temperature, humidity and H2S levels which are important for early warnings of two critical environmental conditions namely forest fires and industrial gas leaks. The temperature sensor has TCR of -0.018/°, the highest of any inkjet-printed sensor and the H2S sensor can detect as low as 3 ppm of gas. These sensors and an antenna have been realized on the walls of a 3D-printed cubic package which encloses the microelectronics developed on a 3D-printed circuit board. Hence, 3D printing and inkjet printing have been combined in order to realize a unique low-cost, fully integrated wireless sensor node. Field tests show that these sensor nodes can wirelessly communicate up to a distance of over 100m. Our proposed sensor node can be a part of internet of things with the aim of providing a better and safe living.