Relevant Radio Frequency Research Articles

Implications of Incident Power Density Limits on Power and EIRP Levels of 5G Millimeter-Wave User Equipment

User equipment (UE) is required to comply with the relevant radio frequency (RF) electromagnetic field (EMF) exposure limits, which are of relevance to establish the maximum permissible transmitted power and the maximum equivalent isotropically radiated power (EIRP). Recently, international RF EMF exposure guidelines, such as those published by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) as well as by the IEEE, have been updated. In this paper, the implications of the revised incident power density limits are investigated in terms of maximum permissible transmitted power and the maximum EIRP for devices operating in close proximity of the user. A similar analysis is conducted according to the US Federal Communications Commission (FCC) regulation on RF exposure. EMF compliance of UE is studied by means of numerical modelling of patch antenna arrays of different array sizes taking into consideration of possible beam-steering operations, at frequencies ranging from 10 GHz to 100 GHz. The results are compared with the 3rd Generation Partnership Project (3GPP) requirements on the total radiated power (TRP) and EIRP levels. The present implications of the incident power density limits for 5G millimeter-wave UE will give valuable insights to mobile equipment manufacturers, network operators, and standardization bodies.

Directive electric–magnetic antenna for ultra‐wideband applications

A novel planar non-dispersive antenna for ultra-wideband radar applications is introduced. The antenna concept is based on the combination of the electromagnetic characteristics of a loop and a planar monopole. A detail discussion on the proposed antenna topology and architecture is presented, and a dedicated backfeeding technique that shows a low transmission loss over a very wide frequency band is suggested. A frequency-independent equivalent circuit of the proposed antenna, useful in the codesign and optimisation of the relevant radio frequency front end is also extracted. It is experimentally demonstrated that the considered radiating element features a fractional bandwidth of 67%, good impedance matching, reasonably constant group delay and uni-directional stable over frequency radiation patterns with front-to-back isolation of about 12 dB.

De Novo Radio Frequency Ablation Therapy: Application of Unexplored Electromagnetic Spectral Resources of mm-Wave/THz Band in Clinical Ablation Procedures – A Review

Review Focus: General considerations on ablation procedure advocated in clinical contexts using electromagnetic (EM) energy are comprehensively reviewed. Relevant radiofrequency (RF) and/or microwave ablation techniques that have been in vogue and in traditional use across clinical procedures are revisited. Traditionally, RF/microwave ablations have been applied to a variety of pathological states, ( in lieu of surgical methods and/or electrocautry procedures) so as to remove unwanted/cancerous tissue layers. Relevantly, new avenues of adopting unexplored electromagnetic (EM) energy falling in the spectral range of mm-wave/THz frequencies for such medical ablation purposes are studied. These higher frequencies for ablation can be considered either to supplant or used in parallel with the existing RF/microwave bands (at 915 MHz and 2.45 GHz). The motivation thereof is to identify certain improved ablation feasibility and derivable merits in clinical sense. Hence, the efficacy of the proposed scheme is identified for two exemplar ablation therapy procedures pertinent to Barrett’s esophagus and menorrhagia. Pertinent pros and cons are discussed and practical ablator designs

Feasibility of future epidemiological studies on possible health effects of mobile phone base stations

The increasing deployment of mobile communication base stations led to an increasing demand for epidemiological studies on possible health effects of radio frequency emissions. The methodological challenges of such studies have been critically evaluated by a panel of scientists in the fields of radiofrequency engineering/dosimetry and epidemiology. Strengths and weaknesses of previous studies have been identified. Dosimetric concepts and crucial aspects in exposure assessment were evaluated in terms of epidemiological studies on different types of outcomes. We conclude that in principle base station epidemiological studies are feasible. However, the exposure contributions from all relevant radio frequency sources have to be taken into account. The applied exposure assessment method should be piloted and validated. Short to medium term effects on physiology or health related quality of life are best investigated by cohort studies. For long term effects, groups with a potential for high exposure need to first be identified; for immediate effect, human laboratory studies are the preferred approach.

Larmor radius expansion for the warm-plasma dielectric tensor

A Larmor radius expansion for the dielectric tensor of an inhomogeneous plasma is derived directly from the relativistic Vlasov equation. Various wave equations for relevant radiofrequency heating problems can be derived, together with a generalized Poynting theorem. The validity of Kadomtsev’s assumption is discussed.