Integrated front end antenna
View Patent ↗A radio frequency transmitting and receiving apparatus comprising a filter and an antenna, wherein the input reactance of the antenna is substantially equal in magnitude and opposite in sign to the output reactance of the filter. This reactance relationship permits the antenna and filter to be collocated and avoids transformation of the input and output impedances to the conventional 50 ohms such that the filter and antenna can be connected with a conventional 50 ohm transmission line.
1. An apparatus for receiving radio frequency signals, comprising:
an antenna for operating within a frequency band having an antenna reactance at antenna terminals;
a filter having a filter reactance at filter input terminals, the filter for producing a filtering effect on certain radio frequency signals; and
wherein the antenna reactance and the filter reactance are opposite in sign and substantially equal in magnitude at frequencies within the frequency band, and wherein the antenna terminals are differentially connected to the filter input terminals to substantially cancel the effects of the antenna reactance and the filter reactance.
2. The apparatus of claim 1 further comprising receiving components responsive to the filter.
3. The apparatus of claim 2 further comprising a transmission line connecting the filter and the receiving components.
4. The apparatus of claim 3 wherein the transmission line comprises one of a fiber optic transmission line and a coaxial cable transmission line.
5. The apparatus of claim 1 wherein the antenna and the filter are disposed within a hand-held communications device.
6. The apparatus of claim 1 further comprising an antenna mast, wherein the filter and the antenna are located in an upper region of the mast.
7. The apparatus of claim 6 further comprising signal receiving components located proximate a base of the mast, and wherein the signal receiving components are connected to the filter by a transmission line.
8. The apparatus of claim 1 wherein the filter exhibits filtering characteristics, further comprising a controller for providing a signal to the filter for changing the filter characteristics.
9. An apparatus for receiving radio frequency signals:
an antenna for operating within a frequency band having an antenna reactance and comprising first and second spaced apart elements, wherein the first element is connected to an antenna feed terminal and the second element is connected to ground;
an electronics module disposed between the first and the second elements, wherein the electronics module comprises a filter having a filter reactance between first and second filter terminals and further comprising the first terminal and the second terminal differentially connected respectively to the first element and to the second element; and
wherein the antenna reactance and the filter reactance are opposite in sign and substantially equal in magnitude at frequencies within the frequency band, and wherein the differential connection causes the antenna reactance to substantially cancel the filter reactance.
10. The apparatus of claim 9 wherein the antenna comprises a meanderline loaded antenna having a top plate, and wherein the first and the second spaced apart elements comprise a first and a second spaced apart leg element of the meanderline antenna, and wherein each of the first and the second leg elements are connected to the top plate via a meanderline conductor.
11. The apparatus of claim 9 operative for receiving and transmitting radio frequency signals, wherein the electronics module further comprises a power amplifier and a switch, and wherein the switch switchably connects one of the power amplifier and the filter to the first and the second spaced apart elements, and wherein the power amplifier is switchably connected to the first and the second elements when the apparatus is operative in the transmitting mode, and the filter is switchably connected to the first and the second elements when the apparatus is operative in the receiving mode.
12. An apparatus for receiving radio frequency signals, comprising:
a substrate;
antenna elements supported by the substrate, wherein each antenna element has an element reactance at element terminals; and
a filter associated with each antenna element, each filter having input terminals, wherein a filter reactance of the filter is opposite in sign and substantially equal in magnitude to the element reactance of the associated antenna element, wherein the antenna element terminals are differentially connected to the filter input terminals causing the filter reactance to substantially cancel the element reactance.
13. The apparatus of claim 12 wherein the substrate comprises a cylindrical sleeve, and wherein the antenna elements are mounted on an outer surface of the sleeve.
14. The apparatus of claim 12 wherein the substrate comprises a polyhedron comprising a plurality of surfaces, and wherein the antenna elements are mounted on one or more of the surfaces.
15. The apparatus of claim 12 further comprising a signal processing element associated with each of the antenna elements for processing the signal received by the associated antenna element, wherein each signal processing element independently processes the signal received by the associated antenna element.
16. The apparatus of claim 15 wherein the filter exhibits filter characteristics, and wherein the signal processing element comprises a controller for controlling the filter characteristics.
17. The apparatus of claim 12 wherein each antenna element is collocated with the associated filter.
18. The apparatus of claim 12 wherein each antenna element is disposed in adjacent relationship with the associated filter.
19. The apparatus of claim 12 further comprising a power amplifier associated with each antenna element, wherein the apparatus operates in a transmitting mode and in a receiving mode, and wherein the power amplifier is operative in the transmitting mode and the filter is operative in the receiving mode.