An Offset-Fed X-Band Reflectarray Antenna Using a Modified Element Rotation Technique

Abstract

1619the hollow shell needs to have r 390 to yield Q=Q Chu = 1:05, whereas the magnetic coating on the PEC core requires only r 100 to reach the same Q=Q Chu = 1:05. IV. CONCLUSIONThe radiation problem for the TM 10 electric current on the surface of a material-coated spherical PEC core is solved analytically using vector spherical wave functions. Closed-form expressions for the electric and magnetic stored energy as well as for the radiation quality factor Q are presented. The optimum relative radius of the PEC core b=a providing the lowest possible Q for a given antenna electrical size ka and material parameters "r and r of the coating is found. It is shown that a PEC core with an electrically thin high-permeability magnetic coating significantly reduces the internal stored energy, and thus the Q of the electric dipole antenna closely approaches the Chu lower bound. For instance, an antenna of the size ka = 0:5 with the relative radius of the PEC core b=a = 0:975 and a pure magnetic coating with r = 400 yields the quality factor Q = 1:01Q Chu . REFERENCES[1] L.

A Low Cross-Polarization Reflectarray Antenna Based on SIW Slot Antenna

“…Up to now, a lot of works have been done to realize the phase response of the reflected surface, such as a phase delay microstrip line and strip line [1], [2], a variable size cell [3], [4], a rotation unit [5], [6]. However, these techniques suffer high cross-polarization level and the antenna efficiency is deteriorated.…”

Single-Layer Dual-Band Dual-Linear-Polarization Reflectarray Antenna With Different Beams for Each Band

“…The main principle for designing a reflectarray antenna is to control the phase of the wave reradiated from the radiating elements to form a planar phase front in the desired direction. Several methods have been used as the phase shift mechanism to obtain the desired reflecting phase, such as using element with variable size [2], phase delay line [3], and element rotation [4].…”

Ka-Band Low Profile Circularly Polarized Reflectarray

“…So, a variety of CP reflectarrays have been proposed in the literature using LP feeder [2][3][4][5][6][7][8] and CP feeder [9][10][11][12][13][14][15]. A reflectarrays using linearly polarized feed can be used where its polarization runs parallel to the diagonal line of the square cell element by tilting the feed by 45 • , and its linearly polarized field is decomposed into two equal components along the sides of the square cell.…”

“…Moreover, each element has the same dimensions and same resonant frequency. Commonly employed elements are short-circuited circular discs [12] and single-layer split square-ring elements [13]. For improving the band of CP reflectarray, a realized single-layer multiple-resonance structure to design two broadband CP reflectarray elements was introduced [14].…”