Ultra-wideband antenna matching
An electronic device may be provided with an antenna resonating element on a first substrate that is mounted to a second substrate. A signal conductor may be coupled to a feed terminal on the antenna resonating element. The signal conductor may include impedance matching structures for the antenna. The impedance matching structures may include an open transmission line stub, a grounded transmission line stub, and a phase shifting segment. The impedance matching structures may configure the antenna to exhibit a wide bandwidth in an ultra-wideband (UWB) frequency band. If desired, the signal conductor may have a phase-shifting segment configured to match a non-50 Ohm impedance of a radio-frequency front end coupled to the signal conductor.
1 . An electronic device comprising:
a flexible printed circuit board with a main body portion and a tail;
a printed circuit mounted to the flexible printed circuit board;
an antenna resonating element on the printed circuit; and
a radio-frequency transmission line having a signal conductor on the flexible printed circuit board that is coupled to the antenna resonating element on the printed circuit, wherein the signal conductor comprises impedance matching structures for the antenna resonating element, the impedance matching structures comprising a grounded transmission line stub on the tail, an open transmission line stub on the main body portion, and a phase shifting segment coupled between the open transmission line stub and the grounded transmission line stub, the phase shifting segment extending between the main body portion and the tail.
2 . The electronic device of claim 1 , further comprising:
a first conductive via that couples the signal conductor to the antenna resonating element through the printed circuit, wherein the phase shifting segment and the grounded transmission line stub are coupled to the first conductive via.
3 . The electronic device of claim 2 , further comprising:
a ground trace on the flexible printed circuit board; and
a second conductive via coupled to the ground trace through the flexible printed circuit board, wherein the grounded transmission line stub extends from the first conductive via to the second conductive via.
4 . The electronic device of claim 3 , wherein the phase shifting segment has a first end coupled to the first conductive via and an opposing second end coupled to the open transmission line stub.
5 . The electronic device of claim 1 , further comprising:
a first conductive via that couples the signal conductor to the antenna resonating element through the printed circuit, wherein the open transmission line stub is coupled to the first conductive via, and the phase shifting segment has a first end coupled to the first conductive via and an opposing second end coupled to the grounded transmission line stub.
6 . The electronic device of claim 1 , further comprising:
peripheral conductive housing structures;
an additional antenna resonating element formed from a segment of the peripheral conductive housing structures; and
an additional signal conductor on the flexible printed circuit board and coupled to a positive antenna feed terminal on the segment.
7 . The electronic device of claim 6 , wherein the antenna resonating element is configured to radiate in an ultra-wideband (UWB) frequency band, further comprising:
a display mounted to the peripheral conductive housing structures; and
a housing wall mounted to the peripheral conductive housing structures opposite the display, wherein the housing wall comprises a dielectric cover layer and a conductive support plate, the conductive support plate has an opening aligned with the antenna resonating element, and the dielectric cover layer is separated from the printed circuit by an air gap.
8 . An electronic device comprising:
a first printed circuit, wherein the first printed circuit comprises a flexible printed circuit board having a main body portion and a tail;
a second printed circuit comprising a rigid printed circuit board mounted to the tail;
an antenna resonating element on the second printed circuit; and
a radio-frequency transmission line having a signal conductor on the first printed circuit that is coupled to the antenna resonating element on the second printed circuit, wherein the signal conductor comprises impedance matching structures for the antenna resonating element, the impedance matching structures comprising:
a grounded transmission line stub on the tail;
an open transmission line stub on the main body portion; and
a phase shifting segment coupled between the grounded transmission line stub and the open transmission line stub, the phase shifting segment extending between the main body portion and the tail.
9 . The electronic device of claim 1 , wherein the signal conductor is coupled to the antenna resonating element at an antenna feed terminal, the grounded transmission line stub is coupled to the antenna feed terminal, and the phase shifting segment has a first end coupled to the antenna feed terminal and has an opposing second end, the open transmission line stub being coupled to the second end of the phase shifting segment.
10 . The electronic device of claim 9 , further comprising:
a radio-frequency connector on the flexible printed circuit board and coupled to the second end of the phase shifting segment and the open transmission line stub.
11 . The electronic device of claim 10 , further comprising:
a transceiver coupled to the radio-frequency connector.
12 . The electronic device of claim 9 , further comprising:
a ground trace on the flexible printed circuit board, wherein the grounded transmission line stub couples the antenna feed terminal to the ground trace.
13 . The electronic device of claim 1 , wherein the printed circuit comprises a rigid printed circuit board.
14 . The electronic device of claim 9 , wherein the antenna resonating element is configured to receive radio-frequency signals in an ultra-wideband (UWB) frequency band.
15 . The electronic device of claim 1 , further comprising:
a radio-frequency front end coupled to the signal conductor and having a non-50 Ohm impedance, wherein the phase shifting segment is configured to match the non-50 Ohm impedance of the radio-frequency front end.
16 . The electronic device of claim 15 , wherein the phase shifting segment is coupled between the radio-frequency front end and the antenna resonating element, the antenna resonating element being configured to convey radio-frequency signals in an ultra-wideband (UWB) frequency band.
17 . An electronic device comprising:
a first printed circuit comprising a flexible printed circuit board, wherein the first printed circuit has a main body portion and a tail;
a second printed circuit mounted to the first printed circuit;
an antenna resonating element on the second printed circuit; and
a radio-frequency transmission line having a signal conductor on the first printed circuit that is coupled to the antenna resonating element on the second printed circuit at an antenna feed terminal, wherein the signal conductor comprises impedance matching structures for the antenna resonating element, the impedance matching structures comprising:
a grounded transmission line stub on the tail and coupled to the antenna feed terminal;
an open transmission line stub on the main body portion; and
a phase shifting segment having a first end coupled to the antenna feed terminal and an opposing second end, wherein the phase shifting segment extends between the main body portion and the tail.