An antenna apparatus includes 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.

An antenna system includes a first antenna element, a second antenna element, a dielectric substrate, a first reflective plate, and a second reflective plate. The first antenna element and the second antenna element are disposed on the dielectric substrate. The first reflective plate is adjacent to the dielectric substrate. The second reflective plate is coupled to the first reflective plate. A first angle is formed between the first reflective plate and the second reflective plate. The antenna system provides a relative large HPBW (Half-Power Beamwidth).

A deployable reflector is configured to transition from a stowed position to a deployed position, passing through various intermediate positions characterized by peaks and valleys, achieving a paraboloid shape when fully deployed. The reflector includes a central polygonal section, which takes the form of an n-sided polygon, and is supported by a set of 2n radial sections. These radial parts extend from the central polygon and widen towards the outer edge. The radial sections are connected by folds that originate from the vertices of the central polygon and extend outward. These folds are arranged so that in the intermediate positions, the valleys alternate with peaks. When the reflector is in its deployed position, the radial sections form a quadratic surface. On the non-reflective side of the radial folds, there are backing elements made from a material that is more elastic than that of the radial parts.

A multi-diameter reflector and a method of assembling the multi-diameter reflector are provided. The reflector includes a reflector shell having a shell diameter, a multi-diameter ring having first and second opposing edges, the multi-diameter ring being structurally adhered to the reflector shell at the first edge, the multi-diameter ring having an outer diameter less than the shell diameter and an inner diameter less than the outer diameter, a panel structurally adhered to the multi-diameter ring at the second edge, the multi-diameter ring having a continuous profile to support structural loads and maintain the reflector shell in a predefined shape.