Antenna feed elements with constant inverted phase
A dipole antenna includes a feed line, first and second microstrip probes, a first signal transmission line coupled to the feed line and to the first microstrip probe, and a second signal transmission line coupled to the feed line and to the second microstrip probe. The first signal transmission line includes a first transmission line including a first signal conductor and a first ground conductor and a second transmission line including a second signal conductor and a second ground conductor. The first signal conductor is electrically coupled to the feed line and to the second ground conductor and the second signal conductor is electrically coupled to the first microstrip probe and the first ground conductor.
1. A crossover transmission line comprising:
an input port;
an output port;
a first transmission line including a first signal conductor and a first ground conductor; and
a second transmission line including a second signal conductor and a second ground conductor,
wherein the first signal conductor is coupled to the input port and to the second ground conductor and the second signal conductor is coupled to the output port and the first ground conductor,
wherein the first transmission line comprises a first coaxial cable including a first inner conductor corresponding to the first signal conductor and a first outer conductor corresponding to the first ground conductor,
wherein the second transmission line comprises a microstrip transmission line including a microstrip conductor corresponding to the second signal conductor and a ground plane corresponding to the second ground conductor,
wherein the first inner conductor is electrically coupled to the ground plane, and
wherein the first outer conductor is electrically coupled to the microstrip conductor.
2. The crossover transmission line of claim 1 , wherein:
the second transmission line comprises a second coaxial cable including a second inner conductor corresponding to the second signal conductor and a second outer conductor corresponding to the second ground conductor;
the first inner conductor is electrically coupled to the second outer conductor; and
the first outer conductor is electrically coupled to the second inner conductor.
3. The crossover transmission line of claim 1 , wherein the first transmission line comprises a first microstrip transmission line including a first microstrip conductor corresponding to the first signal conductor and a first ground plane corresponding to the first ground conductor and the second transmission line comprises a second microstrip transmission line including a second microstrip conductor corresponding to the second signal conductor and a second ground plane corresponding to the second ground conductor;
wherein the crossover transmission line further comprises:
a first balanced transmission line coupled to the first transmission line, the first balanced transmission line including a first signal line and a first ground line;
a second balanced transmission line coupled to the second transmission line, the second balanced transmission line including a second signal line and a second ground line; and
a crossover connection between the first balanced transmission line and the second balanced transmission line, wherein the first signal line is electrically coupled to the second ground line and the first ground line is electrically coupled to the second signal line.
4. The crossover transmission line of claim 3 , further comprising a substrate, wherein:
the first signal line comprises a first conductive trace on a first surface of the substrate;
the first ground line comprises a second conductive trace on a second surface of the substrate opposite the first signal line; and
the first signal line and the first ground line have the same width.
5. The crossover transmission line of claim 4 , wherein:
the second signal line comprises a third conductive trace on the first surface of the substrate;
the second ground line comprises a fourth conductive trace on the second surface of the substrate opposite the first signal line; and
the second signal line and the second ground line have the same width.
6. The crossover transmission line of claim 5 , further comprising:
a first conductive plug extending through the substrate and electrically coupling the first signal line and the second ground line; and
a second conductive plug extending through the substrate and electrically coupling the second signal line and the first ground line.
7. The crossover transmission line of claim 6 , wherein the first ground plane is wider in a direction transverse to a direction of signal propagation through the first transmission line than the first ground line; and
the second ground plane is wider in the direction transverse to current flow through the first transmission line than the second ground line.
8. The crossover transmission line of claim 6 in combination with:
a feed line;
a splitter including an input port and first and second output ports, wherein the feed line is connected to the input port of the splitter and a first end of the crossover transmission line is connected to the first output port of the splitter; and
a first radiating element coupled to a second end of the crossover transmission line.
9. The crossover transmission line of claim 8 , further in combination with:
a second radiating element; and
a non-crossover transmission line having a first end that is connected to the second output port of the splitter and a second end that is connected to the second radiating element.
10. The crossover transmission line of claim 9 , wherein the first and second radiating elements comprise respective first and second microstrip probes.
11. A crossover transmission line comprising:
a first transmission line including a first signal conductor and a first ground conductor;
a second transmission line including a second signal conductor and a second ground conductor, wherein the second transmission line comprises a microstrip transmission line including a microstrip conductor corresponding to the second signal conductor and a ground plane corresponding to the second ground conductor; and
a crossover coupler connected between the first and second transmission lines, wherein the crossover coupler is configured to electrically couple the first signal conductor to the ground plane and to electrically couple the microstrip conductor to the first ground conductor.
12. A crossover transmission line comprising:
an input port;
an output port;
a first microstrip transmission line including a first microstrip conductor coupled to the input port and a first ground plane;
a second microstrip transmission line comprising a second microstrip conductor coupled to the output port and a second ground plane; and
a crossover coupler connected between the first microstrip transmission line and the second microstrip transmission line,
wherein the crossover coupler is configured to electrically couple the first microstrip conductor to the second ground plane and to electrically couple the second microstrip conductor to the first ground plane.
13. The crossover transmission line of claim 12 ,
wherein the crossover coupler is configured to provide a signal at the second microstrip conductor that is approximately 180 degrees out of phase with a signal at the first microstrip conductor over an operational bandwidth.