1. Field of the Invention
The present invention generally relates to an antenna apparatus and an electronic device, and more particularly to an antenna apparatus and an electronic device including a film-like dielectric substrate on which an element including a conductive material pattern is formed.
2. Description of the Related Art
In recent years and continuing, a wireless communication technology using UWB (Ultra-Wide Band) is drawing attention for its ability to perform radar positioning and large capacity communications. In 2002, the U.S Federal Communication Commission (FCC) approved the use of the UWB in a frequency band of 3.1-10.6 GHz.
The UWB is a communications technology for communicating pulse signals in an ultra wide band. Therefore, an antenna used for UWB is desired to have a configuration that allows transmission/reception in an ultra wide band.
As for an antenna to be used at least in the frequency band of 3.1-10.6 GHz approved by the FCC, an antenna having an earth plate and a feeder member (power supply member) is proposed (See Institute of Electronics, Information and Communication Engineers, B-1-133, “Horizontal In-Plane Non-Directional/Low VSWR Antenna for FCC Approved UWB”, Takuya Taniguchi, Takehiko Kobayashi, Tokyo Denki University, Class B201, Presented on Mar. 22, 2003).
FIGS. 1A and 1B are schematic drawings showing conventional antenna apparatuses.
FIG. 1A shows an antenna apparatus 10 having an inverted circular cone-shaped feeder member 12 situated on an earth plate 11.
The side plane of the circular cone-shaped feeder member 12 is configured to form an angle of θ degrees with respect to the surface of the earth plate 11. A desired property can be obtained by adjusting the angle.
FIG. 1B shows another antenna apparatus 20 having a droplet (teardrop) shaped feeder member 22 situated on the earth plate 11. The feeder member 22 includes a circular cone part 22a and a sphere part 22b inscribed to the circular cone part 22a. 
In such state, the feeder member 12, 22 of the antenna 10, 20 is connected to a filter 31, as shown in FIG. 2. The filter 31 extracts a desired frequency band component from the radio waves received by the feeder member 12, 22. The component extracted by the filter 31 is supplied to a transmission/reception unit 32. The transmission/reception unit 32 performs a signal process on the received radio wave as a pre-process or a post-process.
Since the conventional antenna apparatuses 10, 20 are configured having a circular cone shape or a teardrop shape feeder member 12, 22 on a flat earth plate 11, the conventional antenna apparatuses 10, 20 have a relatively large size. Accordingly, it is desired to fabricate an antenna apparatus having a smaller and thinner size.
In terms of an antenna apparatus for low frequency band communication, there is a loop antenna which includes an element(s) fabricated by forming a conductive pattern on a flexible substrate.
Nevertheless, the conventional antenna apparatus for ultra wideband communication has a bulky large size. Therefore, it is difficult to mount the antenna apparatus for ultra wideband communication on an electronic device. Accordingly, there is a demand for an antenna apparatus for ultra wideband communication that has a small and thin configuration, such as the loop antenna for low frequency band communication.