Communications device with helical slot radiating antenna and related antenna device and method
A communications device may include an RF device, and an antenna coupled to the RF device. The RF device may have a conductive ground plane, a conductive support rod carried by the conductive ground plane and extending outwardly therefrom, and a conductive body coupled to and surrounding the conductive support rod. The conductive body may have a helical slot to define a helical slot radiating antenna.
1. A communications device comprising:
a radio frequency (RF) device; and
an antenna coupled to the RF device and comprising
a conductive ground plane,
a conductive support rod carried by the conductive ground plane and extending outwardly therefrom, and
a conductive body coupled to and surrounding the conductive support rod, the conductive body extending from the conductive support rod to define an outer radial edge, the conductive body having a helical slot extending from the conductive support rod to the outer radial edge of the conductive body and to define a helical slot radiating antenna, the conductive body having a proximal end defining a first gap with adjacent portions of the conductive ground plane; and
a first coaxial cable coupling the RF device and the antenna, the first coaxial cable comprising an inner conductor and an outer conductor surrounding the inner conductor, the outer conductor coupled to the conductive ground plane and the inner conductor extending through the conductive ground plane and coupled to the proximal end of the conductive body.
2. The communications device of claim 1 wherein the conductive ground plane has a width greater than a diameter of the conductive body.
3. The communications device of claim 1 wherein the conductive ground plane comprises a conductive tuning body extending upwardly to define a second gap with the proximal end of the conductive body, the second gap being smaller than a width of the first gap.
4. The communications device of claim 1 wherein the antenna comprises a conductive disc element coupled to a distal end of the conductive support rod.
5. The communications device of claim 4 comprising a second coaxial cable coupling the RF device and the antenna, the second coaxial cable coupled to the conductive disc element.
6. The communications device of claim 5 wherein the second coaxial cable comprises an inner conductor, and an outer conductor surrounding the inner conductor, the inner conductor of the second coaxial cable helically wrapping around the conductive body and being coupled to the conductive disc element.
7. The communications device of claim 1 wherein the helical slot has an increasing helical pitch in a direction extending from the conductive ground plane.
8. The communications device of claim 1 wherein the helical slot has a varying diameter in a direction extending from the conductive ground plane.
9. The communications device of claim 1 wherein the antenna has an operating frequency; wherein the helical slot has a diameter between 0.9 and 1.3 wavelengths of the operating frequency; wherein the conductive support rod has a diameter between 0.2 and 0.4 wavelengths of the operating frequency; and wherein a thickness of each turn of the helical slot is between 0.1 and 0.3 wavelengths of the operating frequency.
10. An antenna device for a radio frequency (RF) device, the antenna device comprising:
a conductive ground plane;
a conductive support rod carried by the conductive ground plane and extending outwardly therefrom;
a conductive body coupled to and surrounding the conductive support rod, the conductive body extending from the conductive support rod to define an outer radial edge, the conductive body having a helical slot extending from the conductive support rod to the outer radial edge of the conductive body and to define a helical slot radiating antenna, the conductive body having a proximal end defining a first gap with adjacent portions of the conductive ground plane; and
a first coaxial cable for coupling to the RF device, the first coaxial cable comprising an inner conductor and an outer conductor surrounding the inner conductor, the outer conductor coupled to the conductive ground plane and the inner conductor extending through the conductive ground plane and coupled to the proximal end of the conductive body.
11. The antenna device of claim 10 wherein the conductive ground plane has a width greater than a diameter of the conductive body.
12. The antenna device of claim 10 wherein the conductive ground plane comprises a conductive tuning body extending upwardly to define a second gap with the proximal end of the conductive body, the second gap being smaller than a width of the first gap.
13. The antenna device of claim 10 comprising a conductive disc element coupled to a distal end of the conductive support rod.
14. The antenna device of claim 13 wherein a second coaxial cable is coupled to the RF device, the second coaxial cable coupled to the conductive disc element.
15. The antenna device of claim 14 wherein the second coaxial cable comprises an inner conductor, and an outer conductor surrounding the inner conductor, the inner conductor of the second coaxial cable helically wrapping around the conductive body and being coupled to the conductive disc element.
16. The antenna device of claim 10 wherein the helical slot has an increasing helical pitch in a direction extending from the conductive ground plane.
17. The antenna device of claim 10 wherein the helical slot has a varying diameter in a direction extending from the conductive ground plane.
18. A method for making an antenna for a communications device, the method comprising:
forming a conductive body coupled to and surrounding a conductive support rod carried by a conductive ground plane and extending outwardly therefrom, the conductive body extending from the conductive support rod to define an outer radial edge, the conductive body having a helical slot extending from the conductive support rod to the outer radial edge of the conductive body and to define a helical slot radiating antenna, and the conductive body having a proximal end defining a first gap with adjacent portions of the conductive ground plane; and
coupling a first coaxial cable to the antenna, the first coaxial cable comprising an inner conductor and an outer conductor surrounding the inner conductor, the outer conductor coupled to the conductive ground plane and the inner conductor extending through the conductive ground plane and coupled to the proximal end of the conductive body.
19. The method of claim 18 wherein the conductive ground plane has a width greater than a diameter of the conductive body.
20. The method of claim 18 wherein the conductive ground plane comprises a conductive tuning body extending upwardly to define a second gap with the proximal end of the conductive body, the second gap being smaller than a width of the first gap.