Abstract
In reflector system design, achieving high stability of phase center position with changes in frequency in reflector feed antennas is highly desired. However, obtaining highly stable phase center is not possible for UWB feed antennas, specially for planar ones. Thus, an optimum positioning for the UWB feed antenna should be defined. Optimization of the positioning of the feed antenna is essential since this process lowers resulting phase error losses significantly. In this work, a novel method for optimizing the UWB feed position of a prime focus reflector antenna from phase and amplitude recordings of the measured radiated field is introduced. An automatic and fast design procedure, based on Genetic Algorithms, is described. The proposed methodology has been numerically and experimentally assessed. The procedure is introduced by an application example to one of the most commonly used UWB feed antennas in high-performance reflector antenna systems: Linear Tapered Slot Antenna (LTSA). A LTSA antenna operating in 6–25 GHz frequency band is designed and manufactured. The performance of the method is quantified in terms of its phase error losses inE- andH-planes for reflector illumination.
Highlights
One of the critical issues in reflector antenna system design is obtaining a stable phase center at the feed antenna and preventing efficiency reduction due to the defocusing at the frequency band extremes [1]
One way to reduce the phase error loss (PEL) due to ultrawide band (UWB) feed antenna may be to design the UWB feed antenna with an appropriate profile giving a stable phase center. This procedure is applied to horn antennas in [1] and high stability of the phase center position with respect to frequency is achieved at the frequency band extremes
The procedure is introduced with given examples of a reflector system with Linear Tapered Slot Antenna feed working in the 6–25 GHz frequency band
Summary
One of the critical issues in reflector antenna system design is obtaining a stable phase center at the feed antenna and preventing efficiency reduction due to the defocusing at the frequency band extremes [1]. One way to reduce the PELs due to UWB feed antenna may be to design the UWB feed antenna with an appropriate profile giving a stable phase center This procedure is applied to horn antennas in [1] and high stability of the phase center position with respect to frequency is achieved at the frequency band extremes. The goal of this contribution is to propose an optimization technique for the determination of the feed antenna positioning giving the lowest PELs within the predetermined frequency band In this approach, radiation patterns of the feed antenna are used. The position giving the lowest total PEL for the reflector system is determined by shifting the feed antenna pattern on zdirection at every frequency and recalculating the resulting PEL at every iteration This design procedure is automated with Genetic Algorithm (GA) approach. The considerations on the results are given in the last section
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