Tunable antenna

A tunable broadband antenna, comprising:

• a ground plane, wherein the ground plane is a metallic material of a satellite structure or a base of a ground station antenna;
• a cage structure attached to the ground plane and a top plane, wherein the cage structure includes four leg structures in electrically-conductive contact with the top plane where the top plane is a cross-element with eight equilateral elements;
• a first half-loop and a second half-loop, wherein the first and second half-loops are independent from each other, located diagonally to each other within the cage structure, and support transmitting and receiving an electromagnetic field orthogonal to each other;
• and
• a hybrid phase shifter, wherein the hybrid phase shifter shifts a frequency of the first and second half-loops to 90° from each other;
• wherein the ground plane has an inner ground plane with two or more capacitors embedded therein.