Wide-band active antenna system for HF/VHF radio reception
An active antenna system for receiving electromagnetic radiation at frequencies below 100 MHz. The system includes a vertical support mast; a front end electronics unit including an active balun, the front end electronics unit affixed to the support mast; two crossed-dipole antennas affixed oriented at about 90 degrees to each other, each crossed-dipole antenna having two arms formed of electrically conductive material, each arm having an isoceles triangular frame with an apex of the frame electrically connected to a feedpoint of the front end electronics unit, each arm also having a longitudinal member extending from the apex to the center of the base of the triangular shape and a cross member extending between sides of the triangular frame. The system can operate independently or as part of a long wavelength array for astronomical radio telescope applications.
1. An active antenna system for receiving electromagnetic radiation comprising:
a vertical support mast;
a front end electronics unit including an active balun and two circuit boards, the front end electronics unit affixed to the support mast; and
two crossed-dipole antennas oriented at about 90 degrees to each other, each crossed-dipole antenna having two arms formed of electrically conductive material, each arm having an isoceles triangular frame with an apex of the frame electrically connected to a feedpoint of the front end electronics unit, each arm also having a longitudinal member extending from the apex to the center of the base of the triangular frame and a cross member extending between sides of the triangular frame,
each of the two circuit boards having feed points for electrical connection to one of the two crossed-dipole antennas.
2. The active antenna system according to claim 1 , wherein each arm is oriented downward at about 45 degrees from a horizontal plane.
3. The active antenna system according to claim 1 , further comprising:
a ground screen positioned below the cross dipole antennas.
4. The active antenna system according to claim 3 , wherein the ground screen is an electrically conductive wire mesh with a lattice spacing less than twelve inches.
5. The active antenna system according to claim 1 , wherein the circuit boards are affixed back-to-back with their ground planes connected to each other.
6. The active antenna system according to claim 5 , wherein one of the circuit boards is oriented at about 90 degrees with respect to the other of the circuit boards.
7. An active antenna system for receiving electromagnetic radiation comprising:
a vertical support mast;
a front end electronics unit including an active balun, the front end electronics unit affixed to the support mast; and
two crossed-dipole antennas oriented at about 90 degrees to each other,
the front end electronics unit comprising two circuit boards, with each of the two circuit boards having feed points for electrical connection to one of the two crossed-dipole antennas, and
wherein the circuit boards are affixed back-to-back with their ground planes connected to each other, and wherein one of the circuit boards is rotationally oriented at about 90 degrees with respect to the other of the circuit boards.