Space-Time Medium Functions as a Perfect Antenna-Mixer-Amplifier Transceiver

We show that a space-time-varying medium can function as a front-end transceiver, i.e., an antenna-mixer-amplifier. Such a unique functionality is endowed by space-time surface waves associated with complex space-time wave vectors in a subluminal space-time medium. The proposed structure introduces pure frequency up- and down-conversions and with very weak undesired time harmonics. In contrast to other recently proposed space-time mixers, a large frequency up-/down conversion ratio, associated with gain is achievable. Furthermore, as the structure does not operate based on progressive energy transition between the space-time modulation and the incident wave, it possesses a subwavelength thickness (metasurface). Such a multi-functional, highly efficient and compact medium is expected to find various applications in modern wireless telecommunication systems

Theoretical derivation of the stochastic behavior of a WCDMA signal measured with a spectrum analyzer

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A heuristic tool for exposure reduction in indoor wireless networks

A heuristic indoor network planner for exposure calculation and optimization in wireless networks is developed. The model for the electric-field strength in the vicinity of an access point is presented and the WiFi networks are optimized in order not to exceed a maximal electric-field strength at a certain separation from the access points. The influence of the maximally allowed field strength and the assumed minimal separation between the access point and the human is assessed for a typical office building

Evaluacija ljudske izloženosti neionizirajućem zračenju u blizini telekomunikacijskih uređaja u Republici Hrvatskoj

This paper gives an overview of the regulatory acts in non-ionising radiation in the world, with a special emphasis on basic guidelines issued by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). ICNIRP Guidelines are implemented in many countries worldwide. Croatia has also implemented them indirectly through the European Recommendation 1999/519/EC. The Croatian regulatory acts include the Non-Ionising Radiation Protection Act, Ordinance on Electromagnetic Fields (EMF) Protection, and the Ordinance on Basic Requirements for Devices which produce Optical Radiation and Measures for Optical Radiation Protection. Dosimetry and densitometry are compliant with relevant international and European standards. The paper presents an example of densitometric human exposure assessment in complex indoor exposure conditions. In spite of a high number of indoor and outdoor sources and the “worst-case exposure assessment”, the results are within the limits defined by the Croatian EMF Ordinance.Članak daje pregled zakonodavnih akata u svijetu uz popratno objašnjenje ICNIRP naputaka. ICNIRP naputci primjenjuju se u mnogo zemalja diljem svijeta na izravan ili neizravan način. Republika Hrvatska također primjenjuje ove naputke, i to neizravno, prema Preporuci Vijeća Europe 1999/519/EC. U članku je nadalje objašnjeno hrvatsko zakonodavstvo u području neionizirajućeg zračenja. Osnove dozimetrije i denzitometrije su pojašnjene za specijalan slučaj telekomunikacijskih uređaja. Prikazan je jedan primjer mjerenja u unutrašnjosti zgrade s relativno kompleksnom izloženosti GSM osnovnih postaja, jer se radi o postavljenim vanjskim osnovnim postajama, kao i o postajama u unutrašnjosti zgrade. Na kraju su prikazani rezultati mjerenja i uspoređeni s relevantnim vrijednostima u postojećem hrvatskom Pravilniku

Exposure optimization in indoor wireless networks: application to heterogeneous WiFi-LTE case

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