GNSS base station antenna system with reduced sensitivity to reflections from nearby objects
An antenna system includes an electromagnetic radiator assembled on a ground plane. The ground plane containing a nontransparent area in a center of the ground plane and a semitransparent area surrounding the nontransparent area. The nontransparent area is circular in shape. The semitransparent area is generally circular in shape and contains at least one slot. A plurality of vertical conducting elements are in proximity of a boundary between the nontransparent area and the semitransparent area on a bottom side of the ground plane. The vertical conducting elements are arranged in a circle around a center of the electromagnetic radiator.
1. A GNSS (global navigation satellite system) antenna system comprising:
an electromagnetic radiator configured for reception of Right Hand Circularly Polarized GNSS signals, and assembled on an upper side of a ground plane,
wherein the ground plane includes a nontransparent area in a center of the ground plane and a partially transparent area surrounding the nontransparent area, and wherein the partially transparent area reflects 10% to 90% of the GNSS signals at frequency ranges 1165-1300 MHz and 1530-1610 MHz,
wherein either the nontransparent area or the partially transparent area is circular; and
a plurality of vertical conducting elements near a boundary between the nontransparent area and the partially transparent area in the nontransparent area on a bottom side of the ground plane and extending downwards from the ground plane, the vertical conducting elements arranged in a circle of a diameter of at least 155 mm, around a center of the electromagnetic radiator and connected to the ground plane at the nontransparent area.
2. The antenna system of claim 1 , wherein the nontransparent area is a conductive metal surface.
3. The antenna system of claim 1 , wherein the nontransparent area is an impedance surface with imaginary surface impedance of an open circuit.
4. The antenna system of claim 1 , wherein the partially transparent area is a metal surface with a set of slots with discrete or distributed elements.
5. The antenna system of claim 4 , further comprising only one annular slot on a boundary between the nontransparent area and the partially transparent area.
6. The antenna system of claim 1 , wherein the vertical conducting elements are parasitic conducting pins.
7. The antenna system of claim 6 , wherein the conducting pins are cylindrically-shaped.
8. The antenna system of claim 6 , wherein the conducting pins are mushroom-shaped.
9. The antenna system of claim 1 , wherein the conducting pins are bolts inserted into corresponding holes in a ground plane from a top side, and further comprising a nut at an end of each bolt, the nut being galvanically connected to an expanded tip of each pin.
10. The antenna system of claim 1 , further comprising a plurality of resistive elements connecting the nontransparent area and the partially transparent area.
11. The antenna system of claim 10 , wherein the resistive elements are discrete.
12. The antenna system of claim 10 , wherein the resistive elements are distributed.
13. The antenna system of claim 1 , further comprising a plurality of inductive elements connecting the nontransparent area and the partially transparent area.
14. The antenna system of claim 13 , wherein the inductive elements are discrete.
15. The antenna system of claim 13 , wherein the inductive elements are distributed.
16. The antenna system of claim 1 , wherein the partially transparent area is divided into multiple sections arranged circumferentially and having gaps between the sections.
17. The antenna system of claim 16 , further comprising inductive or resistive elements connecting the sections.
18. The antenna system of claim 16 , further comprising inductive or resistive elements connecting at least some of the sections.
19. The antenna system of claim 1 , wherein the partially transparent area is divided into a first set of multiple sections arranged circumferentially and having gaps between the sections, and a second set of multiple sections arranged circumferentially and having gaps between the sections and surrounding the first set.