Wireless Sensor Networks (WSNs) had been applied in Internet of Things (IoT) and in Industry 4.0. Since a WSN system contains multiple wireless sensor nodes, it is necessary to develop a low-power and multiband wireless communication system that satisfies the specifications of the Federal Communications Commission (FCC) and the Certification European (CE). In a WSN system, many devices are of very small size and can be slipped into a Universal Serial Bus (USB), which is capable of connecting to wireless systems and networks, as well as transferring data. These devices are widely known as USB dongles. This paper develops a planar USB dongle antenna for three frequency bands, namely 2.30–2.69 GHz, 3.40–3.70 GHz, and 5.15–5.85 GHz. This study proposes a novel antenna design that uses four loops to develop the multiband USB dongle. The first and second loops construct the low and intermediate frequency ranges. The third loop resonates the high frequency property, while the fourth loop is used to enhance the bandwidth. The performance and power consumption of the proposed multiband planar USB dongle antenna were significantly improved compared to existing multiband designs.
In this paper, a low cost 28 GHz Antenna-in-Package (AIP) for a 5G communication system is designed and investigated. The antenna is implemented on a low-cost FR4 substrate with a phase shift control integrated circuit, AnokiWave phasor integrated circuit (IC). The unit cell where the array antenna and IC are integrated in the same plate constructs a flexible phase array system. Using the AIP unit cell, the desired antenna array can be created, such as 2 × 8, 8 × 8 or 2 × 64 arrays. The study design proposed in this study is a 2 × 2 unit cell structure with dimensions of 18 mm × 14 mm × 0.71 mm. The return loss at a 10 dB bandwidth is 26.5–29.5 GHz while the peak gain of the unit cell achieved 14.4 dBi at 28 GHz.
An SRF cavity is generally manufactured with a shell structure to decrease the temperature of the inner surface and consequently to decrease the rf surface resistance. During operation, the SRF cavity is immersed in a bath of liquid helium while its interior is maintained under ultra-high vacuum. To be loaded under a condition of external pressure at a cryogenic temperature, a pressure test at room temperature is requested for safety examination. Explicit calculation and estimation of buckling to prove its structural strength is thus essential. With a great stress on the cavity, the nonlinear behavior of the stress-strain curve of niobium generates the elastoplastic buckling behavior different from elastic buckling. The stress-strain curve of niobium depends on the formation, fabrication, and treatment, thus modifying the buckling behavior. We investigated the buckling behavior of a 500-MHz SRF cavity under external pressure, for which various stress-strain curves were applied. Finite-element software (ANSYS) was used to calculate the limit pressure and post-buckling behavior, with an incremental arc-length control scheme to include effects of nonlinearities of both the geometry and the material property. Not only the limit pressure but also the buckling mode vary with the assigned material property and boundary conditions.
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