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How well do upper millimeter-wave and terahertz frequency bands enable wireless communications? In this work, we approximate the current and estimate the future communication potential with emphasis on antenna and radio frequency hardware technologies, and radio propagation challenges. This is done by performing link budget evaluations with justified estimates of link budget calculus terms, such as the achievable or required noise figure, transmit power, and antenna gain. Estimates are based on current enabling technologies and needs to advance those. In RF viewpoint the bottlenecks are in generating sufficiently high transmit power and low noise with the support of very high antenna gains. As an example, we discuss opportunities around 300 GHz frequency. Challenges to support 100 Gb/s bit rate at 30 GHz bandwidth on 10-meter link distance is analyzed for different kind of devices.

This paper presents a study on the power distribution within the tissues for abdominal monitoring and implant communications systems. This study is carried out using finite integration technique based simulations with an anatomical voxel model as well as with recently introduced directive on-body antennas designed for in-body communications. The investigation is conducted by evaluating 2D power flow on the cross-cut of the abdomen area to illustrate the propagation inside the different abdominal tissues. Additionally, power values in different parts of the abdomen area, such as in different parts of the small intestine (SI), colon, stomach etc., are calculated. The main purpose is to examine power distribution in the abdominal area with different antenna location options suitable for abdomen monitoring systems. Furthermore, channel characteristics between an endoscope capsule and an on-body antenna are evaluated in two different areas of the SI tract: close to the on-body antenna and further from the on-body antenna. Power distribution information is useful when designing the medical and health monitoring devices for the abdomen area, such as capsule endoscope, gastrointestinal activity monitoring systems, etc.

This study evaluates the feasibility of plane-wave field synthesis (PWS) technique for multiple-input multipleoutput (MIMO) over-the-air (OTA) test facility, where a reference channel model is implemented. The test facility is based on a fading emulator and an anechoic chamber, equipped with multiple field emulating probes. The test facility emulates a radio channel condition using the PWS technique, based on the spherical wave theory. A simulation tool implementing the MIMO OTA field synthesis based on the PWS technique, named WIN-OTA, is established where the WINNER II is chosen as the reference channel model. The simulation results show that the PWS technique reproduces the reference channels accurately in terms of envelope distribution, spatial and temporal correlation, and channel capacity. The WIN-OTA implementation was verified by comparing the emulated fields and the throughput (TP) from the simulations with measurements for a practical MIMO OTA test facility. The results support the feasibility and accuracy of the field synthesis technique and the WIN-OTA implementation in MIMO OTA antenna testing.Index Terms-MIMO, MIMO OTA testing, plane wave, spherical wave expansion. . His current research interests are in the field of millimeter-wave CMOS circuits for integrated radio frontends.

Human body tissues have a strong effect on the antenna operation in wireless body area networks (WBANs). In this study, the authors present the deep investigations of the effect of body tissue thicknesses on the performance of an ultra wideband (UWB) loop antenna by simulations when the antenna is operated on contact with tissues. The planar UWB loop antenna is designed for the examinations, which is targeted to be used in UWB WBAN applications. The effect of tissue thicknesses on the antenna performance is analysed and characterised in the terms of reflection coefficient S11, gain and total antenna efficiency, group delay, radiation patterns and specific absorption rate by simulations. A parametric layered human body tissue model with the frequency‐dependent behaviour is exploited in the investigations. Further, the reflection coefficient of the presented antenna is measured in the different locations of the author's body. The main aim of these investigations is to demonstrate how the thickness of outermost body tissues affects the antenna performance.