Self-resonating antenna
An antenna includes a U-shaped radiator portion having a first extending arm and a second extending arm parallel and adjacent the first extending arm and coupled to the first extending arm by a junction portion, where the first and second extending arms and the junction portion defining a slot. The antenna further includes a ground plane physically coupled only to the first extending arm and a distributed feed element disposed at least partially within the slot and operable to radiate electromagnetic signals within a first frequency range and electrically excite at least portions of the radiator portion at at least a second frequency range having frequencies outside the first frequency range, thereby causing the radiator portion to radiate electromagnetic signals within the second frequency range.
1. An antenna comprising:
a distributed feed element;
a first coupler portion and a second coupler portion sandwiching the distributed feed element, the first coupler portion having first and second ends, the second coupler portion having first and second ends;
a first resonant line portion having a first resonant end physically coupled to the second end of the first coupler portion and a second resonant end;
a second resonant line portion having a first resonant end physically coupled to the second end of the second coupler portion and a second resonant end;
a shunt portion coupling the second resonant end of the first resonant line portion to the second resonant end of the second resonant line portion, the first coupler portion, the second coupler portion, the first resonant line portion, the second resonant line portion, and the shunt portion defining a slot;
a capacitive element bridging the slot and capacitively coupling the first coupler portion to the second coupler portion; and
a ground plane physically coupled only to the first end of the first coupler portion.
2. The antenna according to claim 1 , wherein:
the slot is rectangular.
3. The antenna according to claim 1 , wherein:
the first coupler portion, the second coupler portion, the first resonant line portion, and the second resonant line portion define an approximately 90-degree bend in the slot.
4. The antenna according to claim 3 , further comprising:
an approximately 90-degree bend in the distributed feed element that coincides with the bend in the slot.
5. The antenna according to claim 1 , wherein:
the first end of the second coupler portion defines a gap between the second coupler portion and the ground plane.
6. The antenna according to claim 5 , wherein:
the gap is between approximately 3 mm and approximately 6 mm wide.
7. The antenna according to claim 1 , wherein:
the first resonant line portion is substantially parallel to the second resonant line portion; and
the first and second resonant line portions are substantially perpendicular to the first and second coupler portions.
8. The antenna according to claim 7 , wherein:
the ground plane has a proximal edge; and
the first and second resonant line portions are substantially parallel to the proximal edge of the ground plane.
9. An antenna, comprising:
a ground plane having a proximal edge and an element attached thereto, the element including:
a first foot portion having a proximal end and a distal end, the proximal end physically coupled to the proximal edge of the ground plane;
a second foot portion spaced away from and substantially parallel to the first foot portion, the second foot portion having a proximal end and a distal end, the proximal end spaced away from the proximal edge of the ground plane to define a gap between the second foot portion and the ground plane;
a first leg portion substantially perpendicular to the first and second foot portions and having a proximal end and a distal end, the proximal end coupled to the distal end of the first foot portion;
a second leg portion spaced away from and substantially parallel to the first leg portion, the second leg portion having a proximal end and a distal end, the proximal end coupled to the distal end of the second foot portion, the first and second foot portions and the first and second leg portions defining a continuous slot;
a capacitive element disposed within a portion of the slot and capacitively coupling the first and second foot portions; and
a junction portion coupling the first and second leg portions at their respective distal ends;
a first resonant mode at a first frequency band;
a second resonant mode at a second frequency band; and
a third resonant mode at a third frequency band;
wherein:
in the first resonant mode, the capacitive element resonates and receives electromagnetic radiation;
in the second resonant mode, the capacitive element excites the slot and the slot resonates and receives electromagnetic radiation; and
in the third resonant mode, the first and second foot portions, the first and second leg portions, and the junction portion resonate and receive electromagnetic radiation.
10. The antenna according to claim 9 , wherein:
the slot is rectangular.
11. The antenna according to claim 9 , wherein:
the first and second foot portions and the first and second leg portions define an approximately 90-degree bend in the slot.
12. The antenna according to claim 9 , wherein:
the first frequency band is higher than the second and third frequency bands; and
the second frequency band is higher than the third frequency band.
13. The antenna according to claim 9 , wherein:
the gap is between approximately 3 mm and approximately 6 mm wide.
14. The antenna according to claim 9 , wherein the element is L-shaped.