A broadband technique for determining the electromagnetic properties of isotropic thin-film materials, which uses a coplanar line, is presented. Complex permittivity and permeability are computed from S-parameter measurements of a coplanar cell propagating the dominant mode. Measured /spl epsi//sub /spl tau// and μ/sub /spl tau// data for several materials are presented between 0.05 GHz and 40 GHz. This technique shows a good agreement between measured and predicted data.

Although several bandpass filters have been designed in the recently proposed empty substrate integrated waveguide (ESIW) technology to improve the quality factor and reduce losses with respect to those in SIW and planar technologies, all structures exhibit narrowband properties and none uses the design concept applied in this paper. The idea has been to insert a dielectric element in an ESIW section (DE-ESIW), which can work as a dielectric resonator or impedance inverter depending on the propagation nature of the fundamental mode. Thus, two novel Chebyshev bandpass filters for narrow and wide bandwidths based on this design concept have been designed in this paper in ESIW technology. The narrow bandpass filter has been realized by inserting four dielectric resonators in an evanescent ESIW section and using a coupling matrix synthesis method, whereas the wideband bandpass filter has been implemented by including six dielectric line sections in an ESIW line propagating the fundamental mode and applying a stepped impedance synthesis approach. A novel wideband microstrip to ESIW transition using cubic Bézier curves has also been designed for the successful integration of both narrow and wideband filters with other microstrip components. EM simulation and measurement frequency responses on manufactured prototypes have shown the versatility of the dielectric elements to efficiently implement narrowband and wideband ESIW bandpass filters, using the proposed design techniques based on coupling matrix and stepped impedances, respectively.

High-performance bandpass filters (BPFs) based on substrate integrated waveguide (SIW) and half mode SIW (HMSIW) with Koch fractal electromagnetic bandgap (KFEBG) patterns etched on the waveguide surface are proposed. These BPFs are designed using a new methodology. The BPF responses are improved by applying a chirped and tapered technique to the KFEBG patterns which exhibit a radius-to-period ratio r/a ≥ 0.5. Simulation results and experimental verification are presented. Good values for insertion losses and stopband rejection are achieved.

Low-cost and flexible radio frequency identification (RFID) tag for automatic identification, tracking, and monitoring of blood products is in great demand by the healthcare industry. A robust performance to meet security and traceability requirements in the different blood sample collection and analysis centers is also required. In this paper, a novel low-cost and flexible passive RFID tag is presented for blood sample collection tubes. The tag antenna is based on two compact symmetrical capacitive structures and works at the ultra-high frequency (UHF) European band (865 MHz–868 MHz). The tag antenna is designed considering the whole dielectric parameters such as the blood, substrate and tube. In this way, it operates efficiently in the presence of blood, which has high dielectric permittivity and loss. Measurement results of the proposed tag have confirmed simulation results. The measured performance of the tag shows good matching in the desired frequency band, leading to reading ranges up to 2.2 m, which is 4.4 times higher than typical commercial tags. The potential of this tag as a sensor to monitor the amount of blood contained in clinic tubes is also demonstrated. It is expected that the proposed tag can be useful and effective in future RFID systems to introduce security and traceability in different blood sample collection and analysis centers.

Two modeling techniques of microwave devices are proposed to generate neuro-fuzzy-based models. These techniques use the adaptive neuro-fuzzy inference system approach, which compensates the error between an initial coarse model and an electromagnetic simulator (or measurement data). The aim of these techniques is to generate accurate models from a set of fuzzy if-then rules and coarse models. Models so obtained could be integrated in a toolbox of any commercially available computer-aided design tools for radio frequency/microwave circuits. Results with artificial neural network and neuro-fuzzy based models are listed and discussed for a microwave tunable phase shifter.

A broad-band technique for determining the electromagnetic properties of isotropic film-shaped materials, which uses a microstrip line, is presented. Complex permittivity and permeability are computed from analytical equations and S-parameter measurements of microstrip cells propagating the dominant mode. Measured /spl epsiv//sub r/ and μ/sub r/ data for several materials are presented between 0.05 GHz and 40 GHz. This technique shows a good agreement between measured and predicted data.