We claim:
1. A beamformer comprising:
an input port configured to receive an input electromagnetic signal;
output ports configured to provide output electromagnetic signals; and
controllable time delay elements disposed between the input port and the output ports;
wherein the time delay elements are distributed within a feed network that includes a fractal tree.
2. The beamformer of claim 1, wherein power of each output electromagnetic signal is substantially identical.
3. The beamformer of claim 1, wherein each time delay element is controlled by an analog signal, the analog signal being one of a voltage and a current.
4. The beamformer of claim 1, wherein each time delay element is controlled by a digital signal.
5. The beamformer of claim 4, each time delay element comprising a plurality of branches, each having a pair of switching devices connected in series with different time delays, the branches connected in parallel, wherein the digital signal selects one of the different time delays to act as the time delay.
6. The beamformer of claim 4, wherein each time delay element comprises a plurality of delayers connected in series, each delayer having a different time delay, wherein the digital signal activates from none to all of the plurality of delayers.
7. The beamformer of claim 1, wherein one of a plurality of control signals control a plurality of the time delay elements.
8. The beamformer of claim 7, the fractal tree comprising:
an initiator pattern including a first set of the time delay elements connected with the input port; and
a plurality of generator patterns connected with the initiator pattern, each generator pattern including a second set of the time delay elements and connected with one of a set of the output ports and a set of the plurality of generator patterns,
wherein the time delay elements are controlled by a number of unique control signals equal to 1-2 signals per dimension of beam scanning.
9. The beamformer of claim 8, wherein each generator pattern for a given fractal stage in the fractal feed network is substantially identical.
10. The beamformer of claim 8, wherein the first set of the time delay elements has substantially twice the number of time delay elements as the second set of the time delay elements.
11. The beamformer of claim 10, wherein the time delay elements have substantially identical ranges of controlled time delays.
12. The beamformer of claim 9, wherein the time delay elements of the first set of the time delay elements have different time delays from corresponding time delay elements of the second set of the time delay elements.
13. The beamformer of claim 12, wherein the time delay elements of the first set of the time delay elements have time delays about twice as long as corresponding time delay elements of the second set of the time delay elements.
14. The beamformer of claim 8, wherein the first set of the time delay elements and the second set of the time delay elements have different numbers of time delay elements.
15. The beamformer of claim 14, wherein the time delay elements have substantially identical time delays.
16. The beamformer of claim 14, wherein each time delay element of the first set of the time delay elements corresponds to a plurality of time delay elements of the second set of the time delay elements.
17. The beamformer of claim 14, wherein each time delay element of the first set of the time delay elements corresponds to two time delay elements of the second set of the time delay elements.
18. The beamformer of claim 1, wherein a pointing angle of an electromagnetic beam radiated from the beamformer remains substantially constant over a wide range of frequencies of the electromagnetic beam, being limited by a spacing and bandwidth of radiating elements connected with the output ports.
19. The beamformer of claim 1, wherein the fractal tree is symmetrically arranged around the input port.
20. The beamformer of claim 1, wherein the fractal tree is arranged such that a plurality of T junction power dividers are disposed between the input port and each output port, power of an electromagnetic signal entering each power divider is split substantially equally at a junction of the T junction.
21. The beamformer of claim 1, wherein the fractal tree is arranged such that a plurality of T junction power dividers are disposed between the input port and each output port, power of an electromagnetic signal entering some of the power dividers being split unequally at a junction of the T junction.
22. The beamformer of claim 21, further comprising amplitude tapers disposed within the fractal feed network to reduce sidelobe levels of an antenna pattern formed from electromagnetic signals emitted from the fractal feed network.
23. The beamformer of claim 21, wherein the output ports of the fractal tree form a non-square shape.
24. The beamformer of claim 22, comprising any number of time delay elements other than 3*(22n2n), where n is a natural number.
25. The beamformer of claim 1, wherein the output ports of the fractal tree form a square shape.
26. The beamformer of claim 1, comprising exactly 3*(22n2n) time delay elements, where n is a natural number.
27. The beamformer of claim 1, wherein the beamformer comprises only radio frequency passive components.
28. The beamformer of claim 1, wherein the beamformer comprises integrated printed-circuit antenna elements.
29. The beamformer of claim 1, wherein the beamformer comprises an integrated, monolithic system on a printed circuit board.
30. The beamformer of claim 1, wherein the output electromagnetic signals have a maximum wavelength of transmission such that the output ports are spaced between about 0.4 to about 0.8 of the maximum free space wavelength apart.
31. The beamformer of claim 1, wherein a time delay of the time delay elements is adjustable only once thereby permanently setting the time delay of the time delay elements.
32. The beamformer of claim 1, wherein a time delay of each time delay element is increased from an unactivated time delay when a control signal is applied to the time delay element to activate the time delay.
33. The beamformer of claim 1, wherein a time delay of each time delay element is decreased from an unactivated time delay when a control signal is applied to the time delay element to activate the time delay.
34. The beamformer of claim 1, wherein a time delay of each time delay element is both increasable and decreasable from an unactivated time delay dependent on a control signal applied to the time delay element to activate the time delay.
35. A beamformer comprising:
an input means for receiving an input electromagnetic signal;
a plurality of output means for providing an output electromagnetic signal;
distribution means for distributing electromagnetic signals through a fractal tree; and
a plurality of time delay means for selectively delaying the distributed electromagnetic signals, the time delay means distributed within the fractal tree.
36. The beamformer of claim 35, wherein each time delay means is controlled by a digital electronic signal.
37. The beamformer of claim 35, wherein one of a plurality of control signals control a plurality of the time delay means.
38. The beamformer of claim 37, wherein the time delay means are controlled by a number of unique control signals equal to 1-2 signals per dimension of beam scanning.
39. The beamformer of claim 35, wherein each time delay means is substantially identical.
40. The beamformer of claim 35, wherein each time delay means has a substantially different time delay from other time delay means.
41. The beamformer of claim 35, wherein the time delay means are distributed symmetrically.
42. The beamformer of claim 35, wherein a pointing angle of an electromagnetic beam radiated from the beamformer remains substantially constant over a wide range of frequencies of the electromagnetic beam, being limited by a spacing and bandwidth of radiating means connected with the output means.
43. The beamformer of claim 35, wherein power of the output electromagnetic signals is substantially identical.
44. The beamformer of claim 35, wherein power of at least one output electromagnetic signal is different from power of the other output electromagnetic signals.
45. The beamformer of claim 44, further comprising a taper means for reducing sidelobe levels of the output electromagnetic signals.
46. The beamformer of claim 35, wherein the time delay means are radio frequency passive.
47. The beamformer of claim 35, wherein a time delay of the time delay means are adjustable only once thereby permanently setting the time delay of the time delay means.
48. The beamformer of claim 35, wherein a time delay of each time delay means is increased from an unactivated time delay when a control signal is applied to the time delay means to activate the time delay.
49. The beamformer of claim 35, wherein a time delay of each time delay means is decreased from an unactivated time delay when a control signal is applied to the time delay means to activate the time delay.
50. The beamformer of claim 35, wherein a time delay of each time delay means is both increasable and decreasable from an unactivated time delay dependent on a control signal applied to the time delay means to activate the time delay.
51. A method for forming an electromagnetic beam, the method comprising:
receiving an input electromagnetic signal in an input port;
responsive to the input electromagnetic signal, distributing electromagnetic signals through a fractal tree;
transmitting the distributed electromagnetic signals through time delay elements distributed throughout the fractal tree;
emitting the delayed distributed electromagnetic signal from a plurality of output ports; and
radiating a main beam into space from an array of antenna elements connected to the output ports.
52. The method of claim 51, further comprising controlling a time delay of the time delay elements.
53. The method of claim 51, wherein the electromagnetic signals are distributed such that power of each output electromagnetic signal is substantially identical.
54. The method of claim 52, further comprising scanning the main beam from the fractal array of radiating elements in exactly one dimension.
55. The method of claim 52, further comprising scanning the main beam from the fractal array of radiating elements in exactly two dimensions.
56. The method of claim 52, further comprising continuously varying the time delay of at least one the time delay element using an analog signal.
57. The method of claim 52, further comprising incrementally varying the time delay of at least one the time delay element using a digital signal.
58. The method of claim 51, further comprising selecting one time delay by completing a transmission path through one of a plurality of parallel-connected delayers having different time delays.
59. The method of claim 51, further comprising activating from none to all of a plurality of series-connected delayers having different time delays.
60. The method of claim 52, further comprising controlling the time delay elements using fewer unique control signals than a number of time delay elements.
61. The method of claim 51, further comprising distributing the electromagnetic signals symmetrically from the input port to the output ports.
62. The method of claim 52, further comprising permanently setting the time delay of the time delay elements by adjusting the time delay of the time delay elements exactly once.
63. The method of claim 52, further comprising increasing the time delay of at least one time delay element from an unactivated time delay when controlling the time delay element.
64. The method of claim 52, further comprising decreasing the time delay of at least one time delay element from an unactivated time delay when controlling the time delay element.
65. The method of claim 52, further comprising one of increasing and decreasing the time delay of at least one time delay element, whose time delay is both increasable and decreasable, from an unactivated time delay when controlling the time delay element.
66. A beamformer comprising:
an input port configured to receive an input electromagnetic signal;
output ports configured to provide output electromagnetic signals; and
time delay elements disposed between the input port and the output ports, a plurality of the time delay elements being controllable by one of a plurality of control signals; the time delay elements being distributed within a feed network arranged in a fractal tree, the fractal tree having an initiator pattern including a first set of the time delay elements connected with the input port and having a plurality of generator patterns connected with the initiator pattern, each generator pattern including a second set of the time delay elements and being connected with one of a set of the output ports and recursively to another stage of the plurality of generator patterns.
67. The beamformer of claim 66, wherein power of each output electromagnetic signal is substantially identical.
68. The beamformer of claim 66, wherein each time delay element is controlled by an analog signal, the analog signal being one of a voltage and a current.
69. The beamformer of claim 66, wherein each time delay element is controlled by a digital signal.
70. The beamformer of claim 69, each time delay element comprising a plurality of branches, each having a pair of switching devices connected in series with different time delays, the branches being connected in parallel, wherein the digital signal selects one of the different time delays to act as the time delay.
71. The beamformer of claim 69, wherein each time delay element comprises a plurality of delayers connected in series, each delayer having a different delay, wherein the digital signal activates from none to all of the plurality of delayers.
72. The beamformer of claim 66, wherein the number of unique control signals are equal to 1-2 signals per dimension of beam scanning.
73. The beamformer of claim 72, wherein each generator pattern for a given fractal stage in the fractal feed network is substantially identical.
74. The beamformer of claim 72, wherein the first set of the time delay elements has substantially twice the number of time delay elements as the second set of the time delay elements.
75. The beamformer of claim 74, wherein the time delay elements have substantially identical ranges of controllable time delays.
76. The beamformer of claim 73, wherein the time delay elements of the first set of the time delay elements have different time delays from corresponding time delay elements of the second set of the time delay elements.
77. The beamformer of claim 76, wherein the time delay elements of the first set of the time delay elements have time delays about twice as long as corresponding time delay elements of the second set of the time delay elements.
78. The beamformer of claim 72, wherein the first set of the time delay elements and the second set of the time delay elements have different numbers of time delay elements.
79. The beamformer of claim 78, wherein the time delay elements have substantially identical time delays.
80. The beamformer of claim 78, wherein each time delay element of the first set of the time delay elements corresponds to a plurality of time delay elements of the second set of the time delay elements.
81. The beamformer of claim 66, wherein the fractal tree is arranged such that a plurality of T junction power dividers are disposed between the input port and each output port, power of an electromagnetic signal entering each power divider being split substantially equally at a junction of the T junction.
82. The beamformer of claim 66, wherein the fractal tree is arranged such that a plurality of T junction power dividers are disposed between the input port and each output port, power of an electromagnetic signal entering some of the power dividers being split unequally at a junction of the T junction.
83. The beamformer of claim 82, further comprising amplitude tapers disposed within the fractal feed network to reduce sidelobe levels of an antenna pattern formed from electromagnetic signals emitted from the fractal feed network.
84. The beamformer of claim 66, wherein the fractal tree has a square shape with exactly 3*(22n2n) time delay elements, where n is a natural number.
85. The beamformer of claim 66, wherein the beamformer comprises only radio frequency passive components.
86. The beamformer of claim 66, wherein the output electromagnetic signals have a maximum wavelength of transmission such that the output ports are spaced between about 0.4 to about 0.8 of the maximum free space wavelength apart.
87. The beamformer of claim 66, wherein a time delay of the time delay elements are adjustable only once thereby permanently setting the time delay of the time delay elements.
88. The beamformer of claim 66, wherein a time delay of each time delay element is increased from an unactivated time delay when the control signal is applied to the time delay element to activate the time delay.
89. The beamformer of claim 66, wherein a time delay of each time delay element is decreased from an unactivated time delay when the control signal is applied to the time delay element to activate the time delay.
90. The beamformer of claim 66, wherein a time delay of each time delay element is both increasable and decreasable from an unactivated time delay dependent on the control signal applied to the time delay element to activate the time delay.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A system for mounting a sign to a post, the system comprising an elongated channel member adapted to be mounted on a backside of the sign, a bracket adapted to be mounted to the post to which the sign is to be mounted, the bracket having a channel engaging portion adapted to be slidably engaged into the channel member on the backside of the sign, wherein the bracket comprises an endless collar adapted to be fitted over the post, said collar defining at least one transversally oriented hole in which a threaded fastener is threadably engaged with a leading end thereof projecting inwardly of the endless collar for exerting a pushing action on the post in order to secure the collar on the post while at the same time drawing the channel member against the post so as to prevent relative movement between the sign and the bracket.
2. A system as defined in claim 1, wherein said collar has a top edge and a bottom edge, and wherein said channel engaging portion extends beyond said top and bottom edges.
3. A system as defined in claim 2, wherein said channel engaging portion is integrally provided on an outer surface of said collar.
4. A system as defined in claim 3, wherein said channel engaging portion is provided in the form of an enlarged mounting pad on said outer surface of said collar.
5. A system as defined in claim 4, wherein at least two enlarged mounting pads are provided at different locations on said outer surface of said collar.
6. A system as defined in claim 5, wherein two pairs of diametrically opposed mounting pads are provided on said outer surface of said collar.
7. A system as defined in claim 4, wherein said at least one transversally oriented hole comprises a through hole in said enlarged mounting pad.
8. A system as defined in claim 1, wherein said collar has a generally elliptical shape.
9. A system for mounting a sign to a post, the system comprising a collar adapted to tightly surround the post, said collar being provided on an outer surface thereof with at least two rail engaging members each of which is adapted to be located on a different side of the post once the collar has been mounted thereabout, at least one rail slidably engageable with a selected one of said at least two rail engaging members, said at least one rail being adapted to be mounted to a rear surface of the sign, thereby allowing signs to be mounted on at least two different sides of the post, wherein at least one threaded hole is defined in said collar for receiving a threaded fastener, said threaded fastener having a leading end extending internally of said collar for engaging the post, and wherein said at least one threaded hole extends thicknesswise through one of said at least two rail engaging members.
10. (canceled)
11. (canceled)
12. A system as defined in claim 9, wherein said collar is provided in the form of a one-piece extrusion.
13. A system as defined in claim 9, wherein said collar is endless and extends along a continuous line circumscribing a closed space in which the pole is adapted to be received.
14. A system for mounting a sign to an outdoor post, the system comprising an elongated rail adapted to be mounted on a rear surface of the sign, a bracket adapted to be mounted to the outdoor post to which the sign is to be mounted, the bracket having a rail engaging portion adapted to be slidably engaged with the rail, wherein once the position of the sign relative to the post has been adjusted, further sliding movement between the rail engaging portion and the rail is prevented by tightening a threaded fastener extending internally of the bracket against the outdoor post, wherein said bracket includes an endless collar defining a closed space for receiving the post, wherein a threaded hole is defined thicknesswise through said collar for allowing said threaded fastener to project into said closed space in order to engage the post, and wherein said rail engaging portion is provided in the form of a mounting pad integrally formed on an outer surface of said collar, said mounting pad projecting beyond an upper edge and a bottom edge of said collar.
15. (canceled)
16. (canceled)
17. A system as defined in claim 16, wherein a plurality of rail engaging portions are provided at different locations about said collar.
18. (canceled)