Mitigating beam squint in multi-beam forming networks
Systems and methods relating to multi-beam forming networks using an antenna array. A matrix circuit for feeding elements of an antenna array to produce multiple beams is provided. To address beam squint issues, beam squint is mitigated by using a series of phase shifters with specific phase-delay performances between the matrix circuit and the antenna array elements. A linearly increasing or decreasing phase difference in the signals fed into adjacent antenna array elements across the array mitigates or eliminates beam squint in the resulting multiple beams. The phase shifters are programmed to provide this increasing or decreasing phase differences.
1. An antenna system for producing multiple beams, the antenna system comprising:
a plurality of antenna elements;
a multi-beam forming network (MBFN) of circuit elements, said MBFN forming a matrix of circuit elements, said MBFN being coupled between matching loads and said plurality of antenna elements and said MBFN receiving a plurality of input beams;
wherein
said matrix of circuit elements forms rows and columns of couplers, each row of couplers comprising a plurality of row couplers coupled in series by delay lines and each column of couplers comprising a plurality of column couplers coupled in series, at least one column of couplers being between an output port and a column load; and
said antenna system is configured for use in cellular applications.
2. The antenna system according to claim 1 , wherein multiple columns of couplers are between an output port and a column load.
3. The antenna system according to claim 1 , further comprising phase shifters that generate linearly decreased phase differences for cancelling beam squint in beams produced by said antenna system.
4. The antenna system according to claim 1 , further comprising phase shifters that generate linearly increased phase differences for cancelling beam squint in beams produced by said antenna system.
5. The antenna system according to claim 1 , further comprising phase shifters, said phase shifters having a same phase delay at a center frequency and said phase shifters having different gradients when a frequency changes.
6. The antenna system according to claim 1 , further comprising phase shifters, said phase shifters having a same phase delay at a center frequency and said phase shifters having different gradients when a frequency changes such that gradients on each signal path in said antenna system will gradually increase with a same difference between adjacent paths.
7. The antenna system according to claim 1 , further comprising phase shifters, said phase shifters having a same phase delay at a center frequency and said phase shifters having different gradients when a frequency changes such that gradients on each signal path in said antenna system will gradually decrease with a same difference between adjacent paths.
8. The antenna system according to claim 1 , further comprising phase shifters wherein a phase shift for said antenna system is configurable such that, as a beam is swept across different frequencies, a phase delay is increased as the frequency increases.
9. The antenna system according to claim 1 , wherein at least one row is between an input port and a row load.
10. The antenna system according to claim 1 , wherein said MBFN of circuit elements is manufactured using a multi-layer structure, said multi-layer construction comprising:
a top copper layer;
a middle copper layer;
a bottom copper layer;
a top substrate layer between said top copper layer and said middle copper layer;
a bottom substrate layer between said middle copper layer and said bottom copper layer.
11. A multi-layer beam forming network (MBFN) circuitry for use with multiple antenna elements for producing multiple beams, the circuitry comprising:
a top copper layer;
a middle copper layer;
a bottom copper layer;
a top substrate layer between said top copper layer and said middle copper layer;
a bottom substrate layer between said middle copper layer and said bottom copper layer;
wherein said MBFN circuitry forms a matrix of circuit elements, s said MBFN receiving a plurality of input beams; and
wherein
said matrix of circuit elements forms rows and columns of couplers, each row of couplers comprising a plurality of row couplers coupled in series by delay lines and each column of couplers comprising a plurality of column couplers coupled in series, at least one column of couplers being between an output port and a column load.
12. The circuitry according to claim 11 , wherein said circuitry is for use in cellular applications.
13. The circuitry according to claim 11 , wherein each column of couplers is between an output port and a column load.
14. The circuitry according to claim 11 , wherein said circuitry further comprises a phase-shifter group, each phase shifter in said phase shifter group being coupled between an antenna element and an output of said matrix.
15. The circuitry according to claim 14 , wherein said phase shifters in said phase shifter group generate linearly decreased phase differences for cancelling beam squint in beams produced by an antenna system to which said MBFN is coupled.
16. The circuitry according to claim 14 , wherein said phase shifters in said phase shifter group generate linearly increased phase differences for cancelling beam squint in beams produced by an antenna system to which said MBFN is coupled.
17. The circuitry according to claim 14 , wherein said phase shifters in said phase shifter group have a same phase delay at a center frequency and said phase shifters have different gradients when a frequency changes.
18. The circuitry according to claim 14 , wherein said phase shifters in said phase shifter group have a same phase delay at a center frequency and said phase shifters have different gradients when a frequency changes such that gradients on each signal path in an antenna system to which said MBFN is coupled will gradually increase with a same difference between adjacent paths.
19. The circuitry according to claim 14 , wherein said phase shifters in said phase shifter group have a same phase delay at a center frequency and said phase shifters have different gradients when a frequency changes such that gradients on each signal path in an antenna system to which said MBFN is coupled will gradually decrease with a same difference between adjacent paths.
20. The circuitry according to claim 14 , wherein said phase shifters in said phase shifter group are configurable such that, as a beam is swept across different frequencies, a phase delay is increased as the frequency increases.
21. The circuitry according to claim 11 , wherein at least one row is between an input port and a row load.