摘要:
A gyrotropic metamaterial structure that include a plurality of chiral metamaterials forming one or more pairs of dipole structures. A plurality of lumped circuits are positioned between the one or more pairs of dipole structures. The lumped circuits have a plurality of subwavelengths antennas that are combined to change the polarization states of an incident polarized wave by producing Faraday-like rotation allowing for nomeciprocal propagation of the incident polarized wave.
摘要:
Methods and systems for mitigating disturbances in a dual gridded reflector antenna are provided. An antenna system that includes a first reflective surface, a second reflective surface, and an intercostal ring is provided. The intercostal ring is configured to connect the first reflective surface and the second reflective surface. A baffle is disposed between the intercostal ring and a path of the electromagnetic waves. The baffle is configured to redirect the electromagnetic waves away from the intercostal ring. Alternatively, the baffle is not present, and the intercostal ring is configured to redirect a perturbed portion of an electromagnetic wave away from wave paths of electromagnetic waves reflected by the first reflective surface and the second reflective surface, respectively.
摘要:
A frequency selective medium that is adapted to receive an incident electromagnetic radiation at an angle of incidence of about 45.degree. has two arrays of conductive elements on opposite parallel surfaces (20, 22) of a dielectric substrate. In one embodiment, the conductive elements are cross-dipoles (6) each having a horizontal dipole (10) and a vertical dipole (8) of different lengths and widths. In another embodiment, the conductive elements comprise a plurality of conductive gridded rectangular loops (40). The frequency selective medium allows incident waves that are within a passband of transmit frequencies to transmit through the medium, and reflects waves at frequencies within a stopband adjacent the passband. In other embodiments, meanderline polarizers (28) are added to cross-dipole and gridded rectangular loop frequency selective media to circularly or dual-linearly polarize incident linearly polarized waves.
摘要:
A microwave oven for radiating microwaves generated from a magnetron into a cavity to heat and cook foodstuff disposed therein, the microwave oven comprising an antenna disposed between a magnetron and the cavity for converting the microwaves to circularly polarized waves to radiate same into the cavity, the microwave oven having the advantage in that the foodstuff in the cavity is heated by radiation of the circularly polarized waves, thereby enabling a uniform heating of the foodstuff and improving an absorption efficiency of microwave energy.
摘要:
A pulse radar for operation at 94 GHz and higher frequencies is shown to include an antenna, a diplexer and first detector that are each optically fed so that radio frequency signals may be, when transmitting, passed through the diplexer to the antenna and, when receiving, from the antenna through the diplexer to the first detector.
摘要:
A spatial filter is provided for electromagnetic waves with circular polarization comprising three parallel conducting networks, the central network being totally reflecting for a rectilinear polarization of given direction and having a non zero reflection coefficient for a rectilinear polarization having a direction perpendicular to the preceding one.
摘要:
A re-polarization means for generating circular polarized electro-magnetic waves using single or multi-layer lattice structure mounted in front of a radiation aperture with the lattice structure comprising a plurality of conductors which extend parallel to each other and/or meander shaped and wherein the lattice structure has one or more additional layers which are closer to the radiation aperture and which has a plurality of parallel conductors but that are inclined by an angle of 45.degree. relative to the direction of the conductors mounted on the other layers which meander. Additionally, orthogonal polarization suppression is achieved with the apparatus of the invention. The invention can be applied to a radom of a target tracking radar antenna, for example.