Sökning: "active antennas"

Visar resultat 1 - 5 av 40 avhandlingar innehållade orden active antennas.

1. 1. Wideband Active and Passive Antenna Solutions for Handheld Terminals

   Författare :Peter Lindberg; Anders Rydberg; Anders Pers; Nicholas Buris; Uppsala universitet; []
   Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Engineering physics; active antennas; impedance matching; dipole antennas; baluns; slot antennas; microstrip antennas; mobile antennas; multifrequency antennas; antenna proximity factors; receiving antennas; ferrite devices; Teknisk fysik;

   Sammanfattning : This thesis presents solutions and studies related to the design of wideband antennas for wireless handheld terminal applications. A method of electrically shortening the terminal chassis length to obtain resonance at high frequencies has been proposed and evaluated, thereby increasing the antennas impedance bandwidth. LÄS MER

3. 2. Integrated Antennas : Monolithic and Hybrid Approaches

   Författare :Erik Öjefors; Anders Rydberg; Sayan Mukherjee; Duixian Liu; Uppsala universitet; []
   Nyckelord :Electronics; antenna travelling wave arrays; antenna phased arrays; phase shifters; micromachining; silicon; monolithic microwave integrated circuits; dipole antennas; loop antennas; slot antennas; Elektronik;

   Sammanfattning : This thesis considers integration of antennas and active electronics manufactured on the same substrate. The main topic is on-chip antennas for commercial silicon processes, but hybrid integration using printed circuit board technology is also addressed. LÄS MER

4. 3. Miniaturized Hard Waveguides in Multifunction Array Antennas

   Författare :Malcolm Ng Mou Kehn; Chalmers University of Technology; []
   Nyckelord :interlaced arrays; Floquet theorem; reflector antennas; focal plane array; multifunction antennas; miniaturized waveguides; multilayer structures; spectral domain technique; periodic structures; aperture reuse; method of moments; soft and hard surfaces; array antennas;

   Sammanfattning : Recent advances in technologies of wireless communications systems have led to an increasing desire for several antennas performing diverse functions at different frequencies to be integrated into a common radiating aperture. This gives rise to the so-called multifunction antenna, which affords the saving of scarce premium real estate and can alleviate problems arising from excessive antenna protrusions in aspects such as aerodynamics, aesthetics, and stealth capability in military applications. LÄS MER

5. 4. Integrated Antenna Solutions for Wireless Sensor and Millimeter-Wave Systems

   Författare :Shi Cheng; Anders Rydberg; Paul Hallbjörner; Zhining Chen; Uppsala universitet; []
   Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; harmonic radar HR ; liquid alloy; millimeter-wave; micromachining; phase shifters; planar inverted cone antennas PICA ; printed circuit boards PCB ; quasi-Yagi antennas; radio frequency microelectromechanical system RF MEMS ; stretchable antennas; substrate integrate waveguides SIW ; T-matched dipole antennas; tapered slot antennas; traveling wave array antennas; ultrawideband UWB ; wireless sensor networks.; Electrical engineering; Elektroteknik; Elektronik; Electronics;

   Sammanfattning : This thesis presents various integrated antenna solutions for different types of systems and applications, e.g. wireless sensors, broadband handsets, advanced base stations, MEMS-based reconfigurable front-ends, automotive anti-collision radars, and large area electronics. LÄS MER

7. 5. Modeling Approaches for Active Antenna Transmitters

   Författare :Parastoo Taghikhani; Chalmers University of Technology; []
   Nyckelord :thermal model.; MIMO; power amplifier; Active antenna transmitter; hybrid beamforming; electrothermal; active subarray antenna; nonlinear distortion;

   Sammanfattning : The rapid growth of data traffic in mobile communications has attracted interest to Multiple-Input-Multiple-Output (MIMO) communication systems at millimeter-wave (mmWave) frequencies. MIMO systems exploit active antenna arrays transmitter configurations to obtain higher energy efficiency and beamforming flexibility. LÄS MER