T2-E: Use of In-Class Wireless Circuits Demonstration to Explain Antenna Concepts to Undergraduate Electrical Engineering Students

Electromagnetics concepts are traditionally considered among the most difficult to understand and least popular by undergraduate students in electrical engineering. Learning of such concepts often requires the understanding of phenomena that are not visible. Therefore, they highly rely on the student’s ability to perform abstract reasoning. In this paper, a demonstration to explain concepts related to antenna electromagnetic radiation, and field polarization, is designed and implemented. An audio signal is transmitted from one side of the classroom to the other, using a simple experimental setup, providing a direct way to sense (hear) the changes in signal intensity to the students. The percentage of students that stated that they had a very clear understanding of antenna radiation and polarization concepts changed increased by 72.5% thanks to the activity. Furthermore, all the students either agreed or strongly agreed that the activity should be implemented in future semesters

Surface Acoustic Wave-Based Flexible Piezocomposite Strain Sensor

A surface acoustic wave (SAW), device composed of polymer and ceramic fillers, exhibiting high piezoelectricity and flexibility, has a wide range of sensing applications in the aerospace field. The demand for flexible SAW sensors has been gradually increasing due to their small size, wireless capability, low fabrication cost, and fast response time. This paper discusses the structural, thermal, and electrical properties of the developed sensor, based on different micro- and nano-fillers, such as lead zirconate titanate (PZT), calcium copper titanate (CCTO), and carbon nanotubes (CNTs), along with polyvinylidene fluoride (PVDF) as a polymer matrix. The piezocomposite substrate of the SAW sensor is fabricated using a hot press, while interdigital transducers (IDTs) are deposited through 3D printing. The piezoelectric properties are also enhanced using a non-contact corona poling technique under a high electric field to align the dipoles. Results show that the developed passive strain sensor can measure mechanical strains by examining the frequency shifts of the detected wave signals

Surface Acoustic Wave-Based Flexible Piezocomposite Strain Sensor

A surface acoustic wave (SAW), device composed of polymer and ceramic fillers, exhibiting high piezoelectricity and flexibility, has a wide range of sensing applications in the aerospace field. The demand for flexible SAW sensors has been gradually increasing due to their small size, wireless capability, low fabrication cost, and fast response time. This paper discusses the structural, thermal, and electrical properties of the developed sensor, based on different micro- and nano-fillers, such as lead zirconate titanate (PZT), calcium copper titanate (CCTO), and carbon nanotubes (CNTs), along with polyvinylidene fluoride (PVDF) as a polymer matrix. The piezocomposite substrate of the SAW sensor is fabricated using a hot press, while interdigital transducers (IDTs) are deposited through 3D printing. The piezoelectric properties are also enhanced using a non-contact corona poling technique under a high electric field to align the dipoles. Results show that the developed passive strain sensor can measure mechanical strains by examining the frequency shifts of the detected wave signals

Metallic 3D Printed Ka-Band Pyramidal Horn Using Binder Jetting

Metallic RF-Microwave components fabricated using additive manufacturing are continually being demonstrated as viable solutions in terms of cost and performance when compared to components fabricated by traditional methods such as machining. In this work, binder jetting is used to fabricate a Ka-Band pyramidal horn antenna, as a test structure to evaluate the performance of this metal 3D printing technology. The measured parameters (S11 and radiation pattern) have good agreement with the simulated ones. The measured return loss is \u3e20 dB across the band. The simulated antenna gain is 8.43 dBi (at 26.5 GHz), and simulations show that the performance degradation due to the finite conductivity and surface roughness is less than 0.1 dBi

Meshed Rectangular Waveguide for High Power Low Loss and Reduced Weight Applications

Additive manufacturing technologies are increasingly being demonstrated to be useful for microwave circuits, showing improved performance in multiple cases. In this work, a meshed rectangular waveguide structure is presented as an option for high power, low loss, but also reduced weight applications. A set of meshed Ku band waveguides was fabricated using binder jetting 3D printing technology showing that the weight can be reduced by 22% with an increase in loss of only 5%, from 0.019 dB/cm for the solid part to 0.020 dB/cm average across the band with the meshed design. Further weight reduction is possible if higher loss is allowed. To demonstrate the concept, a comparison is made between non-meshed and meshed waveguide 4 pole Chebyshev filters