Antenna apparatus

An antenna apparatus comprising:

• N (2=<N) transmitting antennas configured to transmit RF signals having Orbital Angular Momentum (OAM) of designated modes;
• and
• N receiving antennas configured to make N pairs with the N transmitting antennas, respectively, and to receive the RF signals having OAM of the designated modes transmitted from the corresponding N transmitting antennas within the N pairs,
• wherein the transmitting antennas include output parts that output the RF signals, first transmitting filters that transmit the RF signals output from the output parts, and first parabola reflectors that reflect the RF signals transmitted through the first transmitting filters, and total delays of delays given by the first transmitting filters to the RF signals and delays given by the first parabola reflectors realize mode conversion of the RF signals output from the output parts to the RF signals having OAM of the designated modes, and
• wherein the receiving antennas include second parabola reflectors that reflect the RF signals having OAM of the designated modes transmitted from the transmitting antennas, second transmitting filters that give delays to the RF signals output from the second parabola reflectors, and receiving parts that receives the RF signals transmitted through the second transmitting filters, and total delays of delays given by the second parabola reflectors to the RF signals and delays given by the second transmitting filters to the RF signals realize reverse mode conversion of the RF signals input to second parabola reflectors to planar wave RF signals.

A signal transmitting system comprising:

• transmitting antennas configured to have axes as Orbital Angular Momentum (OAM) axes and to transmit signals having OAMs, respectively, the OAMs having distributions of phase delays, respectively, the distributions being obtained by multiplying an angle by proportionality factors, respectively, the proportionality factors being integer numbers, respectively, different to each other, the angle being obtained around the OAM axes;
• and
• receiving antennas configured to have axes as OAM axes and to receive the respective signals,
• wherein the OAM axes of the transmitting antennas and the OAM axes of the receiving antennas are in line with the same lines, respectively,
• wherein the transmitting antennas and the receiving antennas are arranged in pairs, respectively, the OAM axes included in the pairs are arranged on different lines, respectively, and the signals having OAM are transmitted within the same frequency band at the same time period,
• wherein the transmitting antennas include output parts that output the RF signals, first transmitting filters that transmit the RF signals output from the output parts, and first parabola reflectors that reflect the RF signals transmitted through the first transmitting filters, and total delays of delays given by the first transmitting filters to the RF signals and delays given by the first parabola reflectors realize mode conversion of the RF signals output from the output parts to the RF signals having OAM of the designated modes, and
• wherein the receiving antennas include second parabola reflectors that reflect the RF signals having OAM of the designated modes transmitted from the transmitting antennas, second transmitting filters that give delays to the RF signals output from the second parabola reflectors, and receiving parts that receives the RF signals transmitted through the second transmitting filters, and total delays of delays given by the second parabola reflectors to the RF signals and delays given by the second transmitting filters to the RF signals realize reverse mode conversion of the RF signals input to second parabola reflectors to planar wave RF signals.