Methods and systems for calibrating LTE antenna systems

1. An antenna array calibration system, comprising:

a plurality of signal splitter/combiner networks, each of the signal splitter/combiner networks forming a signal input point and a plurality of signal output points;

a calibration network having a signal combining network forming a plurality of calibration source inputs and a calibration signal output, wherein RF signals applied to each of the inputs are combined by the signal combining network into a calibration signal at the calibration signal output, and

wherein each of the signal splitter/combiner networks has a calibration signal sampling point in electrical communication with said signal input point and said signal output points, and wherein each calibration signal sampling point is coupled to a respective calibration source input of the calibration network and located substantially at an electrical midpoint of the signal splitter/combiner network.

2. The antenna array calibration system of claim 1 , wherein each said calibration signal sampling point is capacitively coupled to a respective calibration source input.

3. The antenna array calibration system of claim 1 , further comprising a plurality of calibration signal transmission lines, wherein each of the calibration signal transmission lines comprises a first end connected to one of said calibration source inputs and a second end capacitively coupled to a corresponding one of said signal splitter/combiner networks.

4. The antenna array calibration system of claim 1 , wherein each said signal splitter/combiner networks comprises a capacitive coupling disposed in electrical connection with said calibration signal sampling point, and wherein each calibration signal sampling point is coupled to a respective calibration source input of the calibration network via said capacitive coupling.

5. The antenna array calibration system of claim 4 , wherein said capacitive coupling comprises a transmission line conductive path formed on or above a circuit board, and an air-gap disposed proximate to said transmission line conductive path and configured to receive a conductor of a calibration signal transmission line in communication with said calibration network.

6. The antenna array calibration system of claim 1 , wherein said calibration network further comprises a phase adjusting element associated with each of said inputs.

7. The antenna array calibration system of claim 1 , wherein said calibration network further comprises an amplitude adjusting element associated with each of said inputs.

8. The antenna array calibration system of claim 1 , wherein said plurality of signal splitter/combiner networks comprises at least one phase-shifting network.

9. An antenna array system, comprising:

a plurality of antenna elements arranged in an array having at least two columns, each column having a plurality of antenna elements;

a signal splitter/combiner network associated with each of said columns, each of the signal splitter/combiner networks forming a signal input point and a plurality of signal output points connected to respective antenna elements of said associated column;

an RF transceiver associated with each of said signal splitter/combiner networks, each RF transceiver being connected to the signal input point of said associated signal splitter/combiner networks whereby each RF transceiver is further associated with one of said columns;

a calibration network having a signal combining network defining a plurality of calibration source inputs and a calibration signal output, wherein RF signals applied to each of the inputs are combined by the signal combining network into a calibration signal at the calibration signal output, and wherein an amplitude adjusting element and a phase adjusting element are associated with each of said calibration source inputs, and

wherein each of the signal splitter/combiner networks has a calibration signal sampling point in electrical communication with said signal input point and said signal output points, and wherein each calibration signal sampling point is coupled to a respective calibration source input of the calibration network, and located substantially at an electrical midpoint of the signal splitter/combiner network.

10. The antenna array system of claim 9 , wherein each said calibration signal sampling point is capacitively coupled to its respective calibration source input.

11. The antenna array system of claim 9 , further comprising a plurality of calibration signal transmission lines, wherein each of the calibration signal transmission lines comprises a first end connected to one of said calibration source inputs and a second end capacitively coupled to a corresponding one of said signal splitter/combiner networks.

12. The antenna array system of claim 9 , wherein each said signal splitter/combiner networks comprises a capacitive coupling disposed in electrical connection with said calibration signal sampling point, and wherein each calibration signal sampling point is coupled to a respective calibration source input of the calibration network via said capacitive coupling.

13. The antenna array system of claim 12 , wherein said capacitive coupling comprises a transmission line conductive path formed on or above a circuit board, and an air-gap disposed proximate to said transmission line conductive path and configured to receive a conductor of a calibration signal transmission line in communication with said calibration network.

14. The antenna array system of claim 9 , wherein said plurality of signal splitter/combiner networks comprises at least one phase-shifting network.

15. A method for calibrating an antenna system, comprising:

forming a plurality of signal splitter/combiner networks, each of the signal splitter/combiner networks forming a signal input point and a plurality of signal output points;

forming a calibration network having a signal combining network forming a plurality of calibration source inputs and a calibration signal output,

combining RF signals applied to each of the inputs by the signal combining network into a calibration signal at the calibration signal output, wherein each of the signal splitter/combiner networks has a calibration signal sampling point in electrical communication with said signal input point and said signal output points and located substantially at an electrical midpoint of the signal splitter/combiner network, and

coupling each calibration signal sampling point to a respective calibration source input of the calibration network.

16. The method as in claim 15 further comprising capacitively coupling each calibration signal sampling point to a respective calibration source input.

17. The method as in claim 15 further comprising capacitively coupling each of said signal splitter/combiner networks to said calibration signal sampling point, and coupling each calibration signal sampling point to a respective calibration source input of the calibration network.

18. The method as in claim 17 comprising forming a transmission line conductive path on or above a circuit board, disposing an air-gap proximate to said transmission line conductive path and configured to receive a conductor of a calibration signal transmission line in communication with said calibration network.

19. The method as in claim 15 , wherein said calibration network further comprises an amplitude adjusting element and a phase adjusting element associated with each of said source inputs.

20. The method as in claim 15 , wherein said plurality of signal splitter/combiner networks comprises at least one phase-shifting network.