Sökning: "radio frequency waves"
Visar resultat 6 - 10 av 35 avhandlingar innehållade orden radio frequency waves.
6. Opening New Radio Windows and Bending Twisted Beams
Sammanfattning : In ground based high frequency (HF) radio pumping experiments, absorption of ordinary (O) mode pump waves energises the ionospheric plasma, producing optical emissions and other effects. Pump-induced or natural kilometre-scale field-aligned density depletions are believed to play a role in self-focussing phenomena such as the magnetic zenith (MZ) effect, i. LÄS MER
7. Millimeter-Wave Photonics: Signal Sources and Transmission Links
Sammanfattning : With the use of higher and higher frequencies in a number of current and future wireless millimeter-wave applications it is beneficial to use photonics for several reasons. The use of optical fibers is an advantageous way to transport millimeter-waves in terms of loss, mechanical flexibility, weight, and insensitivity to electromagnetic interference. LÄS MER
8. Secondary Electromagnetic Radiation Generated by HF Pumping of the Ionosphere
Sammanfattning : Electromagnetic waves can be used to transmit information over long distances and are therefore often employed for communication purposes. The electromagnetic waves are reflected off material objects on their paths and interact with the medium through which they propagate. LÄS MER
9. Theory and Applications of Tri-Axial Electromagnetic Field Measurements
Sammanfattning : Polarisation, which was first studied in optics, is a fundamental property of all electromagnetic fields. A convenient way to describe the polarisation of two dimensional electromagnetic fields is given by the Stokes parameters. This thesis deals with different aspects of wave polarisation and electromagnetic field measurements. LÄS MER
10. Wireless Sensor Network and Radio Wave Propagation in Harsh Environments
Sammanfattning : This licentiate thesis cover two important subjects regarding the application of wireless sensor networks (WSNs). Both subjects are related to propagation mechanisms. The first subject is what the radio channel looks like and how it behaves. LÄS MER