Synthesis of a dielectric rod array for a multiple beam reflector antenna
At the Delft University of Technology a new transportable atmospheric radar (TARA), having a sophisticated antenna system, is under construction. The antenna of TARA has multiple beams pointing in different directions. The beams are switched electronically by means of a parabolic dish fed by a dielectric rod array located in the focal plane. Moumen and Ligthart (1999) showed that an array consisting of two dielectric rods separated by 0.77/spl lambda/, where /spl lambda/ stands for the wavelength, is needed in order to achieve a well focused beam at 15/spl deg/ with low side-lobes. However, due to this small separation distance, degradation of the radiation pattern and mismatches, due to mutual coupling, become a serious problem. This paper presents a method to synthesise the dielectric rod array (amplitude and phase distribution) that takes into account mutual coupling effects.
TARA: Transportable Atmospheric Radar
In this article, a new atmospheric profiler is described. The system is mobile in the sense that it can be disassembled and built up at a different location. Some specific characteristics of the antenna system and transportability are highlighted. Less attention is paid to the transmitter and receiver systems as they are of more conventional FM-CW design. A description of the data acquisition and processing system is given.
Microwave source with enhanced radiation power based on orbitron MASERs
We have proposed the design of high power microwave source in a vacuum tube based on the theory of negative mass instability. The proposed source does not operate based on a slow-wave structure but instead makes use of accelerated charged particles. In our structure, an electron emitter injects the charged particles into to the cavity. Emitted particles move around the anode, which leads to electron acceleration and emission of electromagnetic waves with a specific frequency. In this paper, we have enhanced the output power and frequency of microwave source by variation of particles initial energy and the number of anodes incorporating their specific arrangement and applied voltages. Working at room temperature, compactness, wide bandwidth, and tunability of output frequency are among the advantages of the proposed source.