Planar antenna apparatus

An apparatus comprising:

• a signal source, and
• an antenna for emitting an electromagnetic wave according to a signal from the signal source,
• wherein said antenna has a frequency band selected between 3 GHz and 10 GHz,
• wherein said antenna comprises a dielectric substrate, a planar antenna element disposed on the substrate, and a waveguide for propagating electromagnetic waves to or from the planar antenna element, and
• wherein the waveguide comprises at least a first conductor and a second conductor extending along each other, and near a connection portion formed between the first and second conductors and the planar antenna element, there is provided a taper region in which a distance between mutually-facing edge portions of the first conductor and the second conductor increases approximately monotonically toward the planar antenna element.

An apparatus comprising:

• a signal source, and
• an antenna for emitting an electromagnetic wave according to a signal from the signal source,
• wherein said antenna has a frequency band selected between 3 GHz and 10 GHz,
• wherein said antenna comprises a dielectric substrate, and a planar antenna element disposed on the substrate, and
• wherein the planar antenna element comprises teardrop-shaped structures, each composed of a portion of an isosceles triangular shape with a vertical angle of a desired value and an arc of a circle inscribed in the isosceles triangle, arranged with their apexes facing each other.