Part B utilizes the wideband elements developed in Part A, in the RA environment and introduces the performance of the antenna. It is impossible to design a broadband RA using narrowband elements, so wideband elements are developed in a unit cell of a periodic structure to further provide wider overall antenna bandwidth.
New wideband elements for linear polarization LP and circular polarization CP are utilized. The effect of the edge diffraction on Reflectarray antenna thesis phase correction is also investigated. An FSS based flexible portable and rollable circularly polarized TRA design is also presented using the wideband cross Bowtie elements.
This method shows a significant improvement in the RA bandwidth. The element analysis and measurements show promising results.
The measured results of the first ever built flexible, portable textile-RA show good antenna performance.
The RA bandwidth is primarily limited by two factors, the element bandwidth, and the spatial phase delay. The narrow bandwidth is one of the distinct disadvantages of RA. Several RA antennas operating in the Ka-Band are designed and fabricated to learn an understanding of the RA with wideband characteristics.
This issue is solved by introducing a new split aperture into panels that reduce the difference in the path length between the center and those away towards the RA edge. As the RA size is fixed with a proper focal distance, the second factor is hard to be used in the RA bandwidth optimization.
However, when implemented in the RA, the shielded fabric does not perform as expected. The RA provides the advantages of both reflectors and arrays.
The proposed work is categorized into three Parts. This problem is resolved by introducing a dual-sided embroidered reflectarray antenna where a flexible frequency selective surface FSS embroidered at the textile material using a conductive thread is used at the back side of the radiating elements replacing the ground plane.
The experimental results show possible improvements. Therefore, few methods are implemented to improve the antenna reflection coefficients. The radiating elements are embroidered using conductive thread. In part C, textile-reflectarray TRA is proposed using conductive thread and shielded fabric, which is the first to be considered as a new trend in the field of RA.
The initial study showed little effect, but the considered RA size is small to highlight this effect. The matching of the feed is deteriorated when placed in front of the reflector.Fig. Reflectarray with the feed antenna .
84 Fig. Measured radiation pattern of the reflectarray at GHz .
84 Fig. Rectifying antenna: (a) top view and (b) side view . 86 Fig. Table 4. 1. Dimensions of the reflectarray element. 38 Table 4. 2.
Dielectric layers of the reflectarray element . 38 Table 4. 3. Miniaturize element FSS design parameters at X-band .
46 Table 4. 4. Paraboloidal reflector antennas and constrained-fed planar array antennas were for a long time the only options available to the designer to achieve such performance.
However, over the past two decades the reflectarray antenna [1,2] has emerged as an alternative. antenna composed of several dipole antennas of different sizes connected to the same feed; and there is the dish antenna, which works by focusing incoming signals to a small antenna located at the focal point of the dish.
Capability improvement of reflectarray antennas: bandwidth enhancement and reconfigurable design Li, Yuezhou ().
Capability improvement of reflectarray antennas: bandwidth enhancement and reconfigurable design PhD Thesis, School of Information Technology and Electrical Engineering, The University of Queensland. iii Approval of the Thesis: EFFICIENT NUMERICAL ANALYSIS AND DESIGN OF REFLECTARRAY ANTENNAS submitted by ERDİNÇ ERÇİL in partial fulfillment of the requirements for the.Download