A Wideband Waveguide Antenna with Nearly Equal E- and H-Plane Radiation Patterns

Abstract

A novel wideband waveguide antenna with excellent performance is proposed, which is composed of a coaxial-waveguide transition and an open-ended rectangular waveguide loaded with a pair of horizontal umbrella-shaped metallic brims. The brims perpendicular to two broad walls of the waveguide are constructed to modulate the antenna to radiate nearly identical E- and H-plane radiation patterns. A wideband impedance matching performance is achieved with a fractional bandwidth of 40% through the introduction of short-stepped ladders. The antenna has the advantages of simple structure, symmetric radiation pattern, low-cross polarization, moderate back lobe, and almost constant beamwidth.

A Broadband Bessel Beam Launcher Using Metamaterial Lens

“…3 . It can be observed that the distributions are rotationally symmetric, which is guaranteed by the feed with axially symmetric radiation patterns 36 . The symmetric property of the aperture field also guarantees the symmetric property of the beams generated by the lens.…”

“…1(a) . This Bessel beam launcher includes two parts: one is the planar GRIN metamaterial lens and the other is a feed with axially symmetric radiation patterns 36 . In contrast to the axicon setup which needs Gaussian beams for excitation, the GRIN lens is illuminated by a nearly spherical wave emitted from the feed, a broadband waveguide antenna.…”

“…Aditionally, the paraxial approxiamtion is assumed in the design, therefore, the launcher is designed based on the refractive index of the lens without consideration for polarization conversion. The polarization of the beam is based on that of the feed 36 .…”

Multi-beam reflections with flexible control of polarizations by using anisotropic metasurfaces

“…If a feeding source is placed in front of the metasurface with v polarization, then the incident waves are v -polarized waves, and the electric-field vector of E v can be decomposed to E x and E y with | E x | = | E y |, so the x - and y -polarized waves can be controlled independently by phase distributions of the metasurface in x and y directions, respectively. We remark that the feeding source used in our simulations and experiments is a linearly polarized Ku-band (12 GHz–18 GHz) coax-to-waveguide device with nearly equal E- and H-plane radiation patterns39. In the following, three specific examples are investigated by simulations to show the powerful ability of the proposed anisotropic metasurfaces in multi-beam reflections with independent control of polarizations.…”

“…The metasurfaces are composed of Jerusalem Cross structures and a grounded plane spaced by a dielectric substrate. A Ku-band coax-to-waveguide device is placed in front of the metasurfaces used as the feeding source, which can generate quasi-spherical incident waves with linear polarization39. The quasi-spherical incident waves can be reflected by the metasurfaces with high efficiency, while the reflected phases of x - and y -polarized waves can be controlled independently by changing the dimensions of the I-shaped structures on x and y directions, respectively.…”