Dunbao Yan

A circular waveguide antenna using high-impedance ground plane

A high-impedance ground plane (HIGP) is used for a circular waveguide antenna. The benefits of using such a HIGP are related to the suppression of surface waves excited by the circular waveguide mouth, because the HIGP has a very obvious surface wave bandgap. Suppression or reduction of surface waves is expected to improve antenna efficiency and to bring a reduction of sidelobe level due to diffraction of the surface waves. In agreement with the expected result, the measured radiation patterns show that a 2 dB addition in the antenna gain and a 10 dB reduction in the back lobes, if the circular waveguide antenna working frequency is in the HIGP surface wave bandgap.

A novel polarization convert surface based on artificial magnetic conductor

A novel polarization convert surface based on AMC structure is presented. For a linear polarized incident wave, a perpendicular linear polarized reflected wave, right-handed and left-handed circular polarized reflected wave can be achieved individually at different frequency. The surface can be applied to satellite communications to convert polarization state of transmitted and received wave, it can be used to stealth design, and can be used to achieve double circular polarization antenna.

Novel Compact Inter-Embedded AMC Structure for Suppressing Surface Wave

In this paper, a novel very compact inter-embedded artificial magnetic conductor (IE-AMC) structure is presented. Compared with conventional Sievenpiper AMC structure, for a desired band-gap frequency, the cell size of this novel IE-AMC structure is reduced about 70% with the same substrate used. Therefore, in practical application to microwave integrated circuits and antenna arrays for suppressing surface, for a given available space, more AMC structure cells can be used, and the performance of circuits and antennas can be improved more. On the other hand, low frequency surface wave band-gap which is applied to wireless communication band (GSM, PCS and ISM) can be obtained using IE-AMC structure.

Strip-Type AMC Structure and Analysis to Its Band-Gap Characteristic

In this paper, the patch size effect of mushroom-like Sievenpiper AMC (Artificial Magnetic Conductor) structure to reflection phase band-gap is studied. It is observed that the reflection phase band-gap is independent of the size in the direction perpendicular to polarization direction of incident plane wave. Consequently, striptype AMC structure is introduced, and it is noticed this structure has independent reflection phase property and surface wave band-gap property. Compared with mushroom-like Sievenpiper structure, strip-type AMC structure is easier to design and fabrication, and has many advantages in antenna applications to circular patch antenna, plane spiral antenna and corrugated horn antenna etc.

Microstrip dipole antenna with H-shaped aperture coupling

A novel microstrip dipole antenna with H-shaped slot coupled is presented. Several design variations are discussed. Compared to the traditional microstrip dipoles with rectangular coupling slot, this antenna which occupies smaller volume is more suitable to be integrated with other microstrip antenna or active devices.

Study on polarization characteristic of asymmetrical AMC structure

In this paper, the polarization characteristic of asymmetrical AMC structure is studied. And two structures are considered. For different polarization direction of incident wave, different band gap of reflection phase is observed. This characteristic can be utilized to change antenna polarizations.

Waveguide slot antenna using high-impedance surface

High-impedance surface (HIS) is a kind of electromagnetic bandgap (EBG) structure utilized as a ground plane for two waveguide slot antennas in order to improve their radiation characteristics. As compared to a solid metal ground plane, the results suggest that a high-impedance ground plane (HIGP) can significantly improve the patterns of the slot antennas. The ripples in the E-plane patterns of the slot antennas with a metal ground plane are found to vanish, the back lobes are reduced, and the gains are increased.

A novel two-layers compact EBG structure

In this paper, a novel two-layered compact EBG structure is studied. The results show that compared with the normal EBG structure this one can decrease the size of the circuit greatly and can be easily manufactured and applied. Several circuits are manufactured and the measured results are basically in agreement with the simulated results.