Single-layered radial line slot antenna

An inner-feed-type planar antenna of single-layered structure excited by an axially symmetric mode for propagating radio waves from the center toward an outer periphery within a propagation layer having an antenna surface, comprising:

• (a) an axially symmetric mode waveguide member;
• (b) radio-wave connecting means connected to the center of said axially symmetric mode waveguide member;
• (c) a plurality of coupling slots formed in said antenna surface and following along a spiral curve on said antenna surface of said axially symmetric mode waveguide member wherein a proportional coefficient of radiation power per unit length in the radial direction is high at the outer periphery and becomes successively lower as the center is approached;
• (d) a circular, ring-shaped slot provided in the antenna surface at an outer portion of said axially symmetric mode waveguide member;
• and
• (e) a phase adjusting member consisting of dielectric material disposed in a space between a front side and a rear side of said axially symmetric mode waveguide member and in the vicinity or the outer portion of said axially symmetric mode waveguide member for applying a predetermined amount of phase conforming to a circumferential angle.

An inner-feed-type planar antenna of single-layered structure excited by an axially symmetric mode for propagating radio waves from the center toward an outer periphery within a propagation layer having an antenna surface, comprising:

• (a) an axially symmetric mode waveguide member;
• (b) radio-wave connecting means connected to the center of said axially symmetric mode waveguide member;
• (c) a plurality of coupling slots formed in said antenna surface and following along a spiral curve on said antenna surface of said axially symmetric mode waveguide member wherein a proportional coefficient of radiation power per unit length in the radial direction is high at the outer periphery and becomes successively lower as the center is approached;
• (d) a circular, ring-shaped slot provided in the antenna surface at an outer portion of said axially symmetric mode waveguide member;
• and
• (e) at least three waveguide regions which, as seen from the center in the radial direction of said axially symmetric mode waveguide member, are a first waveguide region closest to the center, and having a first dielectric constant, a second waveguide region adjacent to and on a circumference of the first waveguide region, and having a second dielectric constant, and a third waveguide region adjacent to and on a circumference of said second waveguide region, and having a third dielectric constant;
• (f) a phase adjusting member consisting of a dielectric plate, the diameter of which enlarges along a spiral curvature in dependence upon a circumferential angle from the center to the periphery of said waveguide member is arranged inside the radial waveguide formed by a slotted plate and a base plate of said waveguide member, in such a manner that said second dielectric constant being greater than said first dielectric constant, and said second dielectric constant applying a predetermined amount of phase, which conforms to a circumferential angle, to propagating radio waves.