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Planar Band Gap Materials

This improved material relates to novel planar materials having band gap properties, and in particular to such materials formed with fractal patterns. Band gap materials are ideal for shielding electromagnetic (EM) radiation as they have a gap in the transmission band thus blocking transmission of EM radiation. Their conventional three-dimension crystal structures and properties restricted their size and corresponding wavelength range for practical applications. Usually, they are too large and bulky, and must be of the same order of the wavelength of the band gap.

These new planar band gap materials comprise of a conductive fractal pattern formed on a non-conducting planar substrate. They can provide an EM radiation shield where the location of the fractal pattern forming the band gap can be controlled and the band gap properties can be easily altered. They also allow frequency selectivity at a range of incident angles as well as turning the band gap "on" and "off". More important is, yet to perform all these purposes, the dimensions of the material can be smaller than the wavelength at said band gap which is not found in conventional metal reflectors. One of the uses of material is shielding the user of a mobile phone from electromagnetic radiation from the phone antenna. Other possible applications are with radios and microwave ovens.
Technology Benefits
1. Its thickness can be much smaller than the wavelength of the EM wave.
2. Very easy and economical to fabricate
3. It is an "active" photonic band gap system whose property can be controlled by an "external knob"
4. Band gap properties and location can be easily altered
Technology Application
- Cellular phones, radio, microwave ovens, radars, and any applications requiring electromagnetic radiation shielding
Supplementary Information
Patent Number: US6727863B2
Application Number: US2001983852A
Inventor: Wen, Weijia | Sheng, Ping | Chan, Che Ting | Ge, Weikun | Zhou, Lei | Li, Jensen
Priority Date: 26 Oct 2001
Priority Number: US6727863B2
Application Date: 26 Oct 2001
Publication Date: 27 Apr 2004
IPC Current: H01Q000138 | H01Q000500 | H01Q001500 | H01Q001514 | H01Q001700
US Class: 343909 | 343700MS | 343756
Assignee Applicant: The Hong Kong University of Science & Technology
Title: Planar band gap materials
Usefulness: Planar band gap materials
Summary: Used in photonic crystals, e.g. for high pass filters. A sub-wavelength fractal plane can be used to improve the focus of a perpendicular monopole antenna.
Novelty: Planar bandgap material for photonic crystals, has conductive fractal pattern formed on non-conductive planar substrate by subjecting H-shaped mother unit to repeated fine transformation
Sub Category
Application Date
26 Oct 2001
Application No.
US 09/983852
Patent Information
US 6727863
ID No.
Hong Kong

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