Abstract: In a double glazing where a pair of transparent glass sheets are arranged at an interval by having a spacer at the circumferential end portion and where a hollow layer sealed between the pair of glass sheets is formed, there is provided an electromagnetic absorption board used for wireless LAN, which is characterized in that the thickness of the glass sheet is in a range of 2.5-20 mm, that the thickness of the hollow layer is in a range of 2.5-15 mm, that at least one glass sheet of the pair of glass sheets is formed with a resistive film having a surface resistance (surface resistivity) in a range of 20?/? to 2 k?/?, and that the resistive film is formed on a glass sheet side on the hollow layer side.

Abstract: An electromagnetic wave absorbing plate composed of a transparent plate-like dielectric, wherein a thickness of the dielectric is determined such that an electromagnetic wave absorption quantity determined by using an incident side impedance Zxi at a time at which the electromagnetic wave becomes incident on a surface of the dielectric is equal to or higher than 10 dB.

Abstract: In a double glazing where a pair of transparent glass sheets are arranged at an interval by having a spacer at the circumferential end portion and where a hollow layer sealed between the pair of glass sheets is formed, there is provided an electromagnetic absorption board used for wireless LAN, which is characterized in that the thickness of the glass sheet is in a range of 2.5-20 mm, that the thickness of the hollow layer is in a range of 2.5-15 mm, that at least one glass sheet of the pair of glass sheets is formed with a resistive film having a surface resistance (surface resistivity) in a range of 20-2K?/?, and that the resistive film is formed on a glass sheet side on the hollow layer side.

Abstract: An electromagnetic wave absorbing plate composed of a transparent plate-like dielectric, wherein a thickness of the dielectric is determined such that an electromagnetic wave absorption quantity determined by using an incident side impedance Zxi at a time at which the electromagnetic wave becomes incident on a surface of the dielectric is equal to or higher than 10 dB.

Abstract: The invention relates to a method of strengthening a glass article formed of sheet glass produced by the float process. The strengthening method includes a known ion exchange treatment to replace alkali metal ions in the surface layers of the glass with, e.g., alkali metal ions larger in ionic radius such as potassium ions. To prevent warping of the glass article during the ion exchange treatment by the influence of a metal element such as tin used as the molten metal in the float process and diffused into one surface of the sheet glass, the glass article is pretreated by contacting at least said surface with an external source of sodium ions and/or lithium ions and heating the glass article together with the external source of the alkali metal ions at 350.degree.-650.degree. C. for 0.01-100 hr. The pretreatment is neither preceded nor followed by grinding or polishing of said surface of the glass.

Abstract: The invention relates to a method of strengthening a glass article formed of sheet glass produced by the float process. The strengthening method includes a known ion exchange treatment to replace alkali metal ions in the surface layers of the glass with, e.g., alkali metal ions larger in ionic radius such as potassium ions. To prevent warping of the glass article during the ion exchange treatment by the influence of a metal element such as tin used as the molten metal in the float process and diffused into one surface of the sheet glass, the glass article is pretreated by contacting at least said surface with an external source of sodium ions and/or lithium ions and heating the glass article together with the external source of the alkali metal ions at 350.degree.-650.degree. C. for 0.01-100 hr. The pretreatment is neither preceded nor followed by grinding or polishing of said surface of the glass.