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A phased array antenna system with variable electrical tilt comprises an array of antenna elements etc. incorporating a divider dividing a radio frequency (RF) carrier signal into two signals between which a phase shifter introduces a variable phase shift. A phase to power converter converts the pha

A phased array antenna system with variable electrical tilt comprises an array of antenna elements etc. incorporating a divider dividing a radio frequency (RF) carrier signal into two signals between which a phase shifter introduces a variable phase shift. A phase to power converter converts the phase shifted signals into signals with powers dependent on the phase shift. Power splitters divide the converted signals into two sets of divided signals with total number equal to the number of antenna elements in the array. Power to phase converters etc. combine pairs of divided signals from different power splitters this provides vector sum and difference components with appropriate phase for supply to respective pairs of antenna elements etc. located equidistant from an array center. Adjustment of the phase shift provided by phase shifter changes the angle of electrical tilt of the antenna array.

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1. A phased array antenna system with variable electrical tilt and including an array of antenna elements, the phased array antenna system configured to receive a first signal and a second signal, comprising: a variable phase shifter for receiving the first signal and for introducing a variable rela

1. A phased array antenna system with variable electrical tilt and including an array of antenna elements, the phased array antenna system configured to receive a first signal and a second signal, comprising: a variable phase shifter for receiving the first signal and for introducing a variable relative phase shift between the first signal and the second signal;a phase to power converter for converting the first signal and the second signal having the variable relative phase shift into signals whose powers are a function of the variable relative phase shift;first and second power splitters for dividing the first signal and the second signal that are converted into at least two sets of divided signals; andpower to phase converters for combining pairs of the divided signals from different power splitters to provide vector sum and difference components for supply to respective pairs of antenna elements located at like distances with respect to an array center. 2. The phased array antenna system of claim 1, wherein the array of antenna elements comprises an odd number of antenna elements comprising a central antenna element located centrally of each pair of like distant antenna elements. 3. The phased array antenna system of claim 2, further comprising a third power splitter connected between the phase to power converter and one of the first and second power splitters and arranged to divert to the central antenna element a proportion of power from the phase to power converter. 4. The phased array antenna system of claim 1, wherein the phase to power converter and the power to phase converters are combinations of phase shifters and quadrature hybrid couplers. 5. The phased array antenna system of claim 1, wherein the phase to power converter and the power to phase converters are combinations of phase shifters and 180 degree hybrid couplers. 6. The phased array antenna system of claim 1, wherein the variable phase shifter, the phase to power converter, the power to phase converters and the first and second power splitters are co-located with the array of antenna elements as an antenna assembly. 7. The phased array antenna system of claim 1, wherein the variable phase shifter is located remotely from the phase to power converter, the power to phase converters, the first and second power splitters and the array of antenna elements which are co-located as an antenna assembly, and the antenna assembly has dual radio frequency input power feeds from a remote source. 8. The phased array antenna system of claim 7, wherein the variable phase shifter is co-located with the remote source for use by an operator in varying an angle of electrical tilt. 9. The phased array antenna system of claim 7, further comprising duplexers to combine signals passing from or divide signals passing to different operators which share the phased array antenna system. 10. The phased array antenna system of claim 1, wherein the first and second power splitters are arranged to provide for the array of antenna elements to receive drive voltages which fall from a maximum centrally of the array of antenna elements to a minimum at array ends. 11. The phased array antenna system of claim 1, wherein one power splitter of the first and second power splitters is arranged to provide a set of voltages which rise from a minimum to a maximum associated with the array center and ends of the array of antenna elements respectively, to establish a phase front across the array of antenna elements, the phase front being substantially linear as an angle of tilt is increased in a working range of tilt. 12. The phased array antenna system of claim 1, wherein the variable phase shifter is a first variable phase shifter associated with a transmit path, wherein the phased array antenna system comprises a second variable phase shifter associated with a receive path, wherein angles of electrical tilt in a transmit mode and a receive mode are independently adjustable via the first variable phase shifter and the second variable phase shifter, respectively. 13. A method of providing a variable electrical tilt in a phased array antenna system including an array of antenna elements, the phased array antenna system receiving a first signal and a second signal, comprising: introducing a variable relative phase shift between the first signal and the second signal;converting the first signal and the second signal having the variable relative phase shift into signals whose powers are a function of the variable relative phase shift;using power splitters to divide the first signal and the second signal that are converted into at least two sets of divided signals, andcombining pairs of the divided signals from different power splitters to provide vector sum and difference components for supply to respective pairs of antenna elements located at like distances with respect to an array center. 14. The method of claim 13, wherein the array of antenna elements has an odd number of antenna elements comprising a central antenna element located centrally of each pair of like distant antenna elements. 15. The method of claim 14, wherein the phased array antenna system includes a third power splitter connected to receive one of the signals whose power is a function of the variable relative phase shift and the method further comprises using the third power splitter to divert to the central antenna element a proportion of the power. 16. The method of claim 13, wherein the converting of the first signal and the second signal having the variable relative phase shift and the combining of the pairs of divided signals are implemented respectively using phase to power and power to phase converters incorporating 90 or 180 degree hybrid couplers. 17. The method of claim 13, wherein the introducing, the converting, the using, and the combining are implemented using components co-located with the array of antenna elements to form an antenna assembly. 18. The method of claim 13, wherein the introducing is implemented using components located remotely of the array of antenna elements and the converting, the using, and the combining are implemented using components co-located with the array of antenna elements and forming therewith an antenna assembly having dual radio frequency input power feeds from a remote source. 19. The method of claim 18, wherein the introducing includes varying the variable relative phase shift to vary an angle of electrical tilt. 20. The method of claim 18, further comprising: combining signals passing from or dividing signals passing to different operators which share the phased array antenna system. 21. The method of claim 13, further comprising: providing for the array of antenna elements to receive drive voltages which fall from a maximum centrally of the array of antenna elements to a minimum at array ends of the array of antenna elements. 22. The method of claim 13, wherein the using includes providing for one set of divided signals to rise from a minimum to a maximum associated with the array center and ends of the array of antenna elements respectively, to establish a phase front across the array of antenna elements, the phase front being substantially linear as an angle of tilt is increased in a working range of tilt.