Beam shaping techniques for wideband antenna
A technique is described wherein one or multiple reflectors are integrated into a wideband antenna to provide directional radiation pattern characteristics across the frequency range serviced by the antenna. Distributed filters are designed into the reflector assembly to alter electrical performance as a function of frequency. The directive properties provided by the reflector assembly can be adjusted at specific frequency bands to provide a more or less directive radiation pattern. The reflector assembly is designed to maintain low Passive Intermodulation (PIM) characteristics making the technique applicable to high quality Distributed Antenna Systems (DAS) and other applications which require low PIM levels and/or a radiation pattern that can be controlled as a function of frequency.
1. A wideband antenna assembly, comprising:
a radiating element positioned above a ground plane; and
a first reflector positioned in proximity to the radiating element, the first reflector being dimensioned to resonate at a first frequency and to reflect power radiated from the radiating element,
the first reflector comprising a first distributed filter, the first distributed filter,
defining a first resonant slot and a second resonant slot, the first distributed filter further comprising an inductive trace positioned between the first resonant slot and the second resonant slot.
2. The wideband antenna assembly of claim 1 , wherein two or more reflectors are positioned in proximity to the radiating element, wherein each of the two or more reflectors are dimensioned to resonate at one or more frequencies and to reflect power radiated from the radiating element.
3. The wideband antenna assembly of claim 1 , wherein the first distributed filter is designed to alter the electrical characteristics of the first reflector.
4. A wideband antenna assembly, comprising:
a radiating element positioned above a ground plane;
a first reflector positioned adjacent to the radiating element, the first reflector comprising at least one distributed filter;
wherein the first reflector is configured to reflect power radiated from the radiating element and shape a radiation pattern associated with the antenna assembly, and
wherein the at least one distributed filter is configured to alter electrical characteristics of the first reflector;
wherein the at least one distributed filter defines a first resonant slot and a second resonant slot; and
wherein the at least one distributed filter further comprises an inductive trace positioned between the first resonant slot and the second resonant slot.
5. The wideband antenna assembly of claim 4 , wherein the at least one distributed filter is configured to reduce the electrical length of the first reflector as a function of increasing frequency allowing the electrical length of the first reflector to remain optimized as the frequency of operation of the antenna assembly changes.
6. The wideband antenna assembly of claim 4 , the first reflector configured to shape a radiation pattern of the antenna assembly at a first frequency band, the antenna assembly further comprising: a second reflector positioned adjacent to the radiating element, the second reflector configured to shape the radiation pattern of the antenna assembly at a second frequency band, wherein the second frequency band is higher than the first frequency band.
7. The wideband antenna assembly of claim 6 , wherein said second reflector comprises a distributed filter integrated therein.
8. The wideband antenna assembly of claim 4 comprising a plurality of reflectors each positioned adjacent to the radiating element, wherein one or more of the plurality of reflectors comprises a distributed filter integrated therein.
9. The wideband antenna assembly of claim 4 , wherein the first reflector comprises a cross-shape having a horizontal portion and a vertical portion, and wherein one or more distributed filters are disposed about each of the horizontal and vertical portions.
10. The wideband antenna assembly of claim 4 , wherein the first reflector comprises a first conductor portion, a second conductor portion, and a component coupled therebetween.
11. The wideband antenna assembly of claim 10 , wherein the component comprises an inductor, capacitor, or resistor.
12. The wideband antenna assembly of claim 10 , wherein the component comprises a diode, switch, tunable capacitor, field effect transistor (FET), or MEMS device.
13. The wideband antenna assembly of claim 4 , wherein a component is disposed between the pair of resonant slot regions.
14. The wideband antenna assembly of claim 4 , further comprising a radome configured to cover at least the radiating element.
15. The wideband antenna assembly of claim 14 , wherein the first reflector is coupled to the radome.
16. The wideband antenna assembly of claim 4 , wherein the first reflector comprises two or more distributed filters.
17. A wideband antenna assembly, comprising:
a radiating element positioned above a ground plane;
a plurality of first reflectors each positioned adjacent to the radiating element at one or more first distances therefrom, the first reflectors being configured for a first frequency band,
a plurality of second reflectors each positioned adjacent to the radiating element at one or more second distances therefrom, the second reflectors being configured for a second frequency band and each comprising a second distributed filter;
wherein the first frequency band is higher than the second frequency band;
wherein the second distances are further from the radiating element than the first distances;
wherein at least one of the first distributed filter and the second distributed filter defines a first resonant slot and a second resonant slot; and
wherein the at least one of the first distributed filter and the second distributed filter further comprises an inductive trace positioned between the first resonant slot and the second resonant slot.
18. The wideband antenna assembly of claim 1 , wherein the two planar conductive portions are disposed to be coplanar and separated by the first distributed filter.