Improving the capabilities from the antenna point of view at THZ and SUB-THZ frequencies

• Autores: Javier Montero de Paz
• Directores de la Tesis: Daniel Segovia Vargas (dir. tes.)
• Lectura: En la Universidad Carlos III de Madrid ( España ) en 2014
• Idioma: inglés
• Tribunal Calificador de la Tesis: Jordi Romeu Robert (presid.), Luis Emilio Garcia Castillo (secret.), Yi Huang (voc.)
• Materias:
  • Ciencias tecnológicas
    • Tecnología electrónica
      • Antenas
• Enlaces
  • Tesis en acceso abierto en: e-Archivo
• Resumen

  • The main objective of this Ph.D. dissertation is to improve the capabilities of devices (emitters and detectors) and wireless systems (focusing system) at terahertz and sub-terahertz frequencies from the antenna point of view. It has been proved that only acting over the antenna side, devices with better capabilities can be obtained (increased emitted power in emitters and improved responsivity in detectors). This thesis is focused on the analysis and design of planar antennas, so their behaviour at terahertz and sub-terahertz frequencies has been studied. While obtaining the radiation pattern of planar antennas lying on semi-infinite substrate, an anomaly which appears in the radiation pattern is observed. This anomaly does not have a physical meaning but appears in all the published papers. The origin of such anomaly is explained in this thesis. In addition a program capable to obtain in an accurate way the radiation pattern of planar antennas lying on dielectric hyperhemispherical lenses has been designed. Regarding terahertz and sub-terahertz sub-systems a continuous-wave photomixer based power emitter working at 1.05 terahertz has been designed in such a way that maximum power is transferred from the active device to the antenna. The main contribution is that the design has been simplified in such a way that no external elements (filters, etc.) are needed. This emitter is intended to be the local oscillator of a heterodyne detector for radioastronomy applications. In addition, an equivalent circuit based on Hertzian dipoles to obtain the radiation pattern of the so-called “Large Are Emitters" has been derived. Such devices are photomixer based emitters with the main characteristic of not needing an antenna to emit terahertz power. Other important contributions to this Ph.D. dissertation are the complete design of Quasi-Optical Schottky based receiver working within the E-Band (60 - 90 gigahertz) where the power transferred from the antenna to the diode is maximized. This receiver will be part of a complete very high speed wireless communications system. Also in the detectors section, a CMOS FET based receiver working at 300 gigahertz has been designed. Finally, work over a focusing system for a 300 gigahertz radar for security purposes has been done. The main contribution regarding this aspect is that the focusing system, based on two elliptical mirror and a plane one, has been designed in such a way that the beam is capable to scan over a very large area without distortion. To do so it has been imposed that the target distance is always places at the focus of the output mirror.