Monopole antenna design for improved RF antenna efficiency
An electronic device includes a printed circuit board (PCB) with electronics configured to generate and receive data by a radio-frequency carrier signal via a signal terminal. A monopole antenna having first and second ends is connected to a signal terminal of the PCB at the first end. A first section of the antenna extends away from the signal terminal by a first length in a first direction. A second section of the antenna extends away from the first section by a second greater length in a second direction different from the first direction. The first section is spaced apart from the PCB by a third section of the antenna, and the second end of the antenna is spaced apart from the PCB by a dielectric spacer. The length of the antenna may be ¼ of a carrier frequency provided by the signal terminal.
1 . An antenna, comprising:
an antenna element having first and second ends;
a first section of the antenna element extending from the first end to a first bend, the first section including the first end;
a second section of the antenna element extending from the first bend to a second bend;
a third section of the antenna element extending from the second bend to a third bend parallel to the first section; and
a fourth section of the antenna element extending from the third bend to the second end, wherein the fourth section is bendless and is perpendicular to the second section.
2 . The antenna of claim 1 , wherein the antenna element comprises a copper rod.
3 . The antenna of claim 1 , wherein the third section has a first length and the fourth section has a second length and wherein the second length is at least twice the first length.
4 . The antenna of claim 3 , wherein the second section has a third length less than half the first length.
5 . The antenna of claim 4 , wherein the antenna element is formed from a metallic rod, and the third length is about a diameter of the metallic rod.
6 . The antenna of claim 3 , wherein the second length is about 20 mm.
7 . The antenna of claim 1 , wherein the antenna element is driven with a signal having a frequency in a range from 2.40 GHz to 2.48 GHz.
8 . The antenna of claim 1 , wherein the second, third, and fourth sections have a total length of about 29 mm.
9 . The antenna of claim 8 , wherein the second section has a length of about 1 mm, the third section has a length of about 8 mm, and the fourth section has a length of about 20 mm.
10 . The antenna of claim 1 , wherein the antenna element is coupled to a printed circuit board (PCB) by solder, and the fourth section is spaced apart from the PCB.
11 . The antenna of claim 10 , wherein the fourth section is spaced apart from the PCB by a spacer.
12 . The antenna of claim 11 , wherein the spacer comprises dielectric material.
13 . A system, comprising:
a first circuit;
an amplifier coupled to the first circuit; and
an antenna coupled to the amplifier, wherein the antenna comprises an antenna element having first and second ends, a first section of the antenna element extending from the first end to a first bend, the first section including the first end, a second section of the antenna element extending from the first bend to a second bend, a third section of the antenna element extending from the second bend to a third bend parallel to the first section, and a fourth section of the antenna element extending from the third bend to the second end, wherein the fourth section is bendless and is perpendicular to the second section.
14 . The system of claim 13 , wherein the third section has a first length and the fourth section has a second length and wherein the second length is at least twice the first length.
15 . The system of claim 14 , wherein the second section has a third length less than half the first length.