The system is unable to accept submissions at this time.
Fundamental Limits on Antenna Size for Frequency and Time Domain Applications
MetadataShow full item record
As ubiquitous wireless communication becomes part of life, the demand on antenna miniaturization and interference reduction becomes more extreme. However, antenna size and performance are limited by radiation physics, not technology. In order to understand antenna radiation and energy storage mechanisms, classical and alternative viewpoints of radiation are discussed. Unlike the common sense of classical antenna radiation, it is shown that the entire antenna fields contribute to both radiation and energy storage with varying total energy velocity during the radiation process. These observations were obtained through investigating impedance, power, the Poynting vector, and energy velocity of a radiating antenna. Antenna transfer functions were investigated to understand the real-world challenges in antenna design and overall performance. An extended model, using both the singularity expansion method and spherical mode decomposition, is introduced to analyze the characteristics of various antenna types including resonant, frequency-independent, and ultra-wideband antennas. It is shown that the extended model is useful to understand real-world antennas. Observations from antenna radiation physics and transfer function modeling lead to both corrections and extension of the classical fundamental-limit theory on antenna size. Both field and circuit viewpoints of the corrected limit theory are presented. The corrected theory is extended for multi-mode excitation cases and also for ultra-wideband and frequency-independent antennas. Further investigation on the fundamental-limit theory provides new innovations, including a low-Q antenna design approach that reduces antenna interference issues and a generalized approach for designing an antenna close to the theoretical-size limit. Design examples applying these new approaches with simulations and measurements are presented. The extended limit theory and developed antenna design approaches will find many applications to optimize compact antenna solutions with reduced near-field interactions.
- Doctoral Dissertations 
Showing items related by title, author, creator and subject.
Cummings, Nathan Patrick (Virginia Tech, 2003-12-08)Reconfigurable antennas represent a recent innovation in antenna design that changes from classical fixed-form, fixed-function antennas to modifiable structures that can be adapted to fit the requirements of a time varying ...
Smart Antennas at Handsets for the 3G Wideband CDMA Systems and Adaptive Low-Power Rake Combining Schemes Kim, Suk Won (Virginia Tech, 2002-07-02)Smart antenna technology is a promising means to overcome signal impairments in wireless personal communications. When spatial signal processing achieved through smart antennas is combined with temporal signal processing, ...
M. Harun; Ellingson, S. W. (American Geophysical Union, 2011-10-18)A new feed system is designed for operation below 100 MHz. The only existing system on the EVLA operating below 100 MHz is the "4 m" (74 MHz) system which uses crossed half-wave dipoles located in front of the Cassegrain ...