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In this work, a compact, edge-fed modified rectangular patch size, monopole, and ultra-wideband antenna has been presented for their good suitability to millimeter (mm) wave and upper sub-6 GHz frequency range (FR2) for next-generation (5G and beyond) communications. The patch size enhancement approach has been utilized without affecting the original size of the substrate and rectangular patch. The technique provides better impedance matching at the designed frequency of 32.5 GHz. The minimum acceptable gain for an antenna to work well is 5 dBi. The proposed design achieves peak gain of 5.43 dBi and 10.86 dBi at two resonance frequencies of 32.5 GHz and 48.12 GHz within the specified ultra-wideband (UWB). The antenna has low loss as it is fabricated on a compact Rogers RT Duroid 5880 of thickness 1.6 mm. The measured reflection coefficients are found in good agreement with the simulated one. The resultant performance parameters like radiation pattern, reflection coefficient, peak gain, and − 10 dB bandwidth reveal that the antenna performs excellently within 26 to 40 GHz with excellent impedance matching at the resonance frequency. At higher frequencies, the time domain response of the proposed design is also presented. The RLC electrical equivalent circuit of the proposed design is presented at the end and validated using ADS software. [ABSTRACT FROM AUTHOR]

This work presents a symmetrical quad-element multiple-input multiple-output (MIMO) antenna that uses a feasible band for 5G millimeter waves at 38 GHz. The main radiator is a patch antenna with a rectangular shape, and the frequency it operates at is 38 GHz. Etching a three-element split-ring resonator (SRR) metamaterial unit cell onto the normal patch radiator allows for widening the resonance over the desired operating band. The suggested MIMO antenna is built on a Rogers RT5880 substrate material that measures 15 × 15 mm2, has a thickness of 0.8 mm, and has a dielectric constant of 2.2. The results of the measurements show that the antenna is capable of covering a frequency range from 37.3 to 39.3 GHz and can also achieve an inter-port isolation of greater than 20 dB between the antenna elements across both bands without the use of a complex decoupling structure. These are the results that were obtained when the antenna was tested. An equivalent circuit diagram of the electrical responses of the antenna is also presented to get insight into the proposed antenna. This schematic makes use of lumped components. The diversity performance parameters that were analyzed provide an envelope correlation coefficient that is less than 0.005, and a channel capacity loss that is less than 0.35 bits/s/Hz. All of these results fall well within the parameters that are considered acceptable norms. The findings provide evidence that the design is workable for the transmission of millimeter waves at 5G speeds. [ABSTRACT FROM AUTHOR]

In this paper, mm–wave low cost single and multiple input and multiple output (MIMO) planar microstrip antenna suitable for futuristic K–(18–26.5GHz), K a –band (26.5–40GHz) and local multipoint distribution systems (LMDS) applications is presented. The proposed structure achieves impedance bandwidth of 22.77 GHz (17.23–40GHz) with a peak gain of 13.69 dBi that notably covers the LMDS modern wireless communication application requirement. This achieves 5 dBi gain-bandwidth of 9.07 GHz (26.77–35.85GHz) and 17 GHz (19–36GHz) for single element and MIMO antenna with four elements in cascaded form respectively. The improvement in gain and impedance bandwidth is augmented after exciting multiple resonances of antenna by etching of two 3-armed H-shaped slots (3-AHSS) and inverted T-shaped slots (ITSS) symmetrically in the patch. With these etchings the copper losses and vertical components of current are controlled. The fabricated prototype of size 37 × 15 m m 2 is connected through a mm–wave supporting frequency connector of 2.92 mm and 50 Ω coaxial type to Vector Network Analyzer (VNA) Bench of modal number Rohde and Schwarz (ZNB–40) for measurement of performance parameters and it is found to be in good promise with simulated results. [ABSTRACT FROM AUTHOR]

All-metal 3D printing fabrication technologies provide an attractive alternative for direct manufacturing of waveguide components due to fast and cost-effective prototyping and the possibility to fabricate geometries which cannot be fabricated with traditional machining techniques. In radio astronomy, waveguide components in radio receivers are operated at cryogenic temperatures and inside a cryostat under vacuum conditions. In this paper, we report on the design, fabrication by 3D printing and testing at room and cryogenic temperatures of a corrugated horn to be used in astronomical receivers operating in the 35–50-GHz band. [ABSTRACT FROM AUTHOR]

For the first time, a mm-wave personal exposure meter (mm-PEM) for the 5th generation of mobile networks (5G) exposure assessment in indoor diffuse fields is presented. The design is based on simulations and on-phantom calibration measurements in a mm-wave reverberation chamber (RC) at 60 GHz. The mm-PEM consists of an array of nine antennas on the body. Using the mm-PEM, the incident power density (IPD) is measured in the unloaded RC, for the antenna(s) on the phantom and RC loaded with phantom. The uncertainty of the mm-PEM is then determined in terms of its response, which is defined as the ratio of antenna aperture for the above measurement scenarios. Using nine antennas, the designed meter has a response of 1.043 (0.17 dB) at 60 GHz, which is very close to 1 (0 dB), the desired ideal response value. The mm-PEM measured an IPD of 96.6 Wm− 2 at 60 GHz in the RC, for an input power of 1 W. In addition, the average absorption cross-section of the phantom is determined as 225 cm2, which is an excellent agreement with its physical dimensions. [ABSTRACT FROM AUTHOR]

The paper presents the first in vivo glucose monitoring animal study in a pig, which correlates radio frequency signal transmission changes with changes in blood glucose concentration in the 58-62 GHz frequency range. The presented non-invasive glucose sensing system consists of two opposite facing patch antennas sandwiching glucose-loaded samples. Prior to the animal study, the system was tested using saline solution samples, for which a linear relationship between changes in transmitted signal and glucose concentration was observed. In the animal study, glucose concentration changes were induced by injecting a known glucose solution in the blood stream. The non-invasive transmission measurements were compared to the glucose levels obtained invasively from the animal. Our results suggest that the system can detect spikes in glucose concentration in the blood, which is an important milestone towards non-invasive glucose monitoring. [ABSTRACT FROM AUTHOR]

The Atacama Large Millimeter/Sub-millimeter Array (ALMA) is currently the largest (sub-)mm wave telescope in the world and will be used for astronomical observations in all atmospheric windows from 35 to 950 GHz when completed. The ALMA band 1 (35-50 GHz) receiver will be used for the longest wavelength observations with ALMA. Because of the longer wavelength, the size of optics and waveguide components will be larger than for other ALMA bands. In addition, all components will be placed inside the ALMA cryostat in each antenna, which will impose severe mechanical constraints on the size and position of receiver optics components. Due to these constraints, the designs of the corrugated feed horn and lens optics are highly optimized to comply with the stringent ALMA optical requirements. In this paper, we perform several tolerance analyses to check the impact of fabrication errors in such an optimized design. Secondly, we analyze the effects of operating this optics inside the ALMA cryostat, in particular the effects of having the cryostat IR filters placed next to the band 1 feed horn aperture, with the consequent near-field effects. Finally, we report on beam measurements performed on the first three ALMA band 1 receivers inside test cryostats, which satisfy ALMA specifications. In these measurements, we can clearly observe the effects of fabrication tolerances and IR filter effects on prototype receiver performance. [ABSTRACT FROM AUTHOR]

Frequency bands above 6 GHz are being considered for future 5G wireless systems because of the larger bandwidth availability and of the smaller wavelength, which can ease the implementation of high-throughput massive MIMO schemes. However, great challenges are around the corner at each implementation level, including the achievement of a thorough multi-dimensional characterization of the mm-wave radio channel, which represents the base for the realization of reliable and high-performance radio interfaces and system architectures. The main properties of the indoor radio channel at 70 GHz, including angular and temporal dispersion as well as an assessment of the major interaction mechanisms, are investigated in this study by means of UWB directional measurements and ray tracing simulations in a reference, small-indoor office environment. [ABSTRACT FROM AUTHOR]