%0 Journal Article
%T Passive and Active Reconfigurable Scan-Beam Hollow Patch Reflectarray Antennas
%A M. Hajian
%A B. Kuijpers
%A K. Buisman
%A A. Akhnoukh
%A M. Pelk
%A L. C. N. de Vreede
%A J. Zijdeveld
%A L. P. Ligthart
%A C. Spitas
%J ISRN Communications and Networking
%D 2012
%R 10.5402/2012/290534
%X The design concept of passive and active reconfigurable reflectarray antennas has been proposed and tested. The antenna elements in the array are identical hollowed patches. In the first phase of study the slots are loaded with a SMD capacitor to set the required phase shift needed for array implementation. Simulations show promising results. Mounting a SMD capacitor in such a configuration can be considered as the first step in using capacitive loading on a slotted patch for active microstrip reflectarrays. It is shown that by adjusting the capacitance values it is possible to scan the beam. In the second phase, the patch elements are loaded with active varactor-diode device which its reflected phase can be varied. This phase alteration is based on the variation of the diode capacitance which can be achieved by varying the biasing voltage of the active varactor device. In latter approach by activating these varactor devices, the phase of each antenna element in the array configuration can be adopted dynamically and consequently, its beam direction can be reconfigured. The reflectarrays incorporating passive and active elements have been built and tested at 7.0£¿GHz and 6.0£¿GHz, respectively. The performance of the proposed reconfigurable antennas is excellent, and there is good agreement between the theoretical and measurement results which pioneers design of arbitrarily reconfigurable antennas. 1. Introduction In the past decade the research and development on analytical and experimental techniques for Microstrip ReflectArray (MRA) antennas have received a considerable attention. This is due to the their low-cost production, low-weight, and very thin flat leading to a excellent alternative to the traditional reflector antennas. The main objective of recent studies is the development of active reflectarrays. In this paper the passive and active phase shifting techniques for hollowed microstrip antenna elements loaded with Surface Mounted Device (SMD) capacitor and varactor-diode device, respectively, are addressed. There are different types of phasing techniques reported in the literature: stubs [1, 2], where patch antenna elements are loaded with different stubs length, rotation [3], where patch antenna elements are rotated, and variable size [4, 5], where the resonance length of the antenna is adjusted. These conventional methods require alternation of the patch elements geometry in an array. The phase shift technique proposed in this paper is capacitive loading. The antenna element is hollowed patch antenna [6]. The passive and active phasing
%U http://www.hindawi.com/journals/isrn.communications.networking/2012/290534/