Plane antenna and method for manufacturing the same

1. A method for manufacturing a plane antenna that coats dielectric with conductor and forms a pattern free of the conductor using a surface of the dielectric which is otherwise coated with conductor and is made of material having a coefficient of water absorption of 0.01% or less, said method comprising the step of:

molding the dielectric to form the pattern therein through injection molding using a mold that includes the pattern,

forming a first conductor film on the dielectric formed by said molding step, using electroless plating, evaporation or sputtering; and

forming a second conductor film on the dielectric on which the first conductor film has been formed by said step of forming a first conductor film.

2. A method according to claim 1 , wherein the second conductor film is formed by electroplating, and the step of forming the second conductor film includes controlling a film thickness of the second conductor film formed by the electroplating.

3. A method according to claim 1 , wherein the pattern has a concave shape, and the step of forming the first conductor film uses evaporation or sputtering, and includes the step of arranging a patterned surface oblique to an ejection direction of a material of the conductor in the evaporation or sputtering.

4. A method according to claim 3 , wherein the step of forming the second conductor film uses evaporation or sputtering of aluminum.

5. A plane antenna comprising a plate dielectric and a conductor that coats a surface of the dielectric, the plate antenna forming a resonant slot of a predetermined pattern at a predetermined position uncovered with the conductor,

wherein the dielectric is made of a material having a coefficient of water absorption of 0.01% or less, and has a convex section forming the pattern at the predetermined position,

wherein the conductor is arranged approximately as high as the dielectric around the dielectric having the convex section and forms a convex section together with the dielectric having the convex section; and

wherein said plane antenna serves as a high frequency wave array antenna for use with 50 GHz or higher.

6. A plane antenna comprising a plate dielectric and a conductor that coats a surface of the dielectric, the plate antenna forming a resonant slot of a predetermined pattern at a predetermined position on the dielectric uncovered with the conductor,

wherein the dielectric is made of material having a coefficient of water absorption of 0.01% or less, and has a convex section forming the pattern at the predetermined position,

wherein the conductor is arranged approximately as high as the dielectric around the dielectric having the convex section, and forms a convex section together with the dielectric having the convex section, and

wherein d≦h≦λg/10 is satisfied where d is a thickness of the conductor at a location other than the predetermined position, λg is a wavelength of an electric wave, and h is a height of the dielectric having the convex section.

7. A plane antenna according to claim 6 , wherein the wave has a frequency of 50 GHz or higher.

8. A plane antenna comprising a plate dielectric and a conductor that coats a surface of the dielectric, the plate antenna forming a resonant slot of a predetermined pattern at a predetermined position on the dielectric uncovered with the conductor,

wherein the dielectric is made of material having a coefficient of water absorption of 0.01% or less, and has a convex section forming the pattern at the predetermined position,

wherein the conductor is arranged approximately as high as the dielectric around the dielectric having the convex section, and forms a convex section together with the dielectric having the convex section, and

wherein 25 μm≦h≦250 μm is satisfied where h is a height of the dielectric having the convex section.