A novel low-cost beam-steering technique based on the extended-resonance power-dividing method
A novel phased array based on the extended-resonance power-dividing method has been presented. This method eliminates the need for separate power splitter and phase shifters in a conventional phased-array system, resulting in a substantial reduction in circuit complexity and cost. As a proof of principle, a 2-GHz extended-resonance-based phased array using varactor diodes and microstrip patch antennas has been designed, fabricated, and tested. The measured scan range is 20/spl deg/ and the measured efficiency of the extended-resonance phased-array feed is typically 80%, which corresponds to 1 dB of insertion loss.
A Novel Millimeter-Wave Dual-Fed Phased Array for Beam Steering
A novel beam-steering approach is presented based on the superposition of two squinted antenna beams. The two antenna beams are realized by exciting the opposite feeds of a dual-fed array antenna. A change in phase difference and amplitude ratio between the input signals, possibly using only one phase shifter and one variable gain amplifier, steers the main beam in different directions. Additionally, sum and difference patterns can be obtained using this concept, allowing for a monopulse operation with a broad peak or a deep null at broadside. Using this approach, beam nulls can also be steered toward interference directions, while keeping the shape and direction of the main beam unchanged. To verify the concept, a 77-GHz demonstrator using a linear patch array antenna and monolithic microwave integrated circuit in-phase/quadrature modulators has been designed and fabricated. The measurement results show a beam-scanning range of 16 °, well in accord with the simulation results.
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.