Circularly polarized omnidirectional in-building signal booster apparatus and method

• US 8,036,594 B2
• Filed: 12/12/2007
• Issued: 10/11/2011
• Est. Priority Date: 12/12/2007
• Status: Expired due to Fees

• Current Assignee: SPX Corporation
• Original Assignee: SPX Corporation
• Inventors: Schadler, John L.
• Primary Examiner(s): Lee; John J
• Application Number:
  US11/954,694
• Publication Number:
  US 20090156118A1
• Time in Patent Office: 1,399 Days
• Field of Search: 455/3.01, 455/7, 455/13.3, 455/15, 455/24, 455/66.1, 455/67.11, 455/562.1, 455/313, 455/341, 455/25, 455/260, 455/271, 455/3.02, 343/795, 343/872, 343/890
• US Class Current: 455/25
• CPC Class Codes: H01Q 21/205 providing an omnidirectional coverage turnstile aerials H01Q21/26
• CPC Class Codes: H01Q 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• CPC Class Codes: H01Q 21/29 Combinations of different interacting antenna units for giving a desired directional characteristic H01Q25/00 takes precedence
• CPC Class Codes: H04B 7/1555 Selecting relay station antenna mode, e.g. selecting omnidirectional -, directional beams, selecting polarizations

Abstract

A rebroadcasting apparatus for mobile media includes a receiving antenna and a transmitting antenna. The signal to be rebroadcast is received with a circularly polarized directional antenna. The transmitting antenna has circular polarization opposite to the polarization of the receiving antenna. Amplifiers and filters may be included between receiving and transmitting antennas to regulate retransmitted signal quality. The transmitting antenna uses one or more bays of quasi-helical dipole radiators excited using manifold feed equipped with tuning paddles. The transmitting antenna may be formed from light-weight sheet metal or other readily mass-produced materials. The transmitting antenna may be housed within an ordinary security camera enclosure or similar radio-transparent housing.

Claims

1. A system for rebroadcasting a source signal originating from a location external to the system, comprising:

a receiving antenna configured to acquire a broadcast radio transmission, wherein directionality of the receiving antenna in elevation and azimuth and receiving antenna gain are prescribed, and wherein receiving antenna polarization is elliptical with a first handedness;

a transmitting antenna configured to radiate a broadcast radio transmission, wherein a radiation pattern of the transmitting antenna is substantially omnidirectional with respect to azimuth, and wherein transmitting antenna polarization is elliptical with a second handedness; and

an interconnecting signal line coupling the receiving and transmitting antennas.

2. The system of claim 1, further comprising:

an amplifier interposed between the receiving and transmitting antennas, wherein the amplifier has an input port and an output port; and

a second interconnecting signal line, wherein the respective signal lines couple signals from the receiving antenna to the amplifier input port and from the amplifier output port to the transmitting antenna.

3. The system of claim 2, wherein at least one interconnecting signal line is a coaxial cable.

4. The system of claim 2, wherein the amplifier further comprises:

a gain stage, wherein the gain stage provides a prescribed extent of amplification for broadcasting;

an automatic gain control (AGC), wherein a broadband signal power level at the amplifier output port is so regulated by the AGC as to have a lesser variation than the source signal applied to the amplifier input port; and

a filter, wherein signal energy applied to the amplifier input port that falls outside a prescribed frequency passband is attenuated at least in part.

5. The system of claim 4, wherein the filter compensates in-band signals at least in part for frequency-dependent signal phase and magnitude changes introduced within the system.

6. The system of claim 2, wherein at least one interconnecting signal line is a fiber optic cable.

7. The system of claim 1, further comprising a transmitting antenna radome, wherein the transmitting antenna radome encloses the transmitting antenna at least in part.

8. The system of claim 1, further comprising a receiving antenna radome, wherein the receiving antenna radome encloses the receiving antenna at least in part.

9. The system of claim 1, further comprising:

a receiving antenna mount configured to permit positioning and retention of the receiving antenna in an orientation that supports reception of the source signal, wherein a range and precision of adjustment and a characteristic of mechanical stability of the receiving antenna mount are compatible with the directionality of the receiving antenna and of an anticipated level of system maintenance; and

a transmitting antenna mount configured to permit positioning and retention of the transmitting antenna in an orientation that supports propagation of the signal emitted by the transmitting antenna.

10. The system of claim 1, further comprising a signal passthrough fitting, wherein the receiving antenna is located externally to an enclosing structure that impedes electromagnetic wave propagation over a range of frequencies, wherein the transmitting antenna is located internally to the enclosing structure, and wherein the signal passthrough fitting accommodates passage of a signal carried by the interconnecting signal line between the respective antennas.

11. The system of claim 1, wherein the receiving antenna and the transmitting antenna are both located internally to an enclosing structure that impedes propagation of electromagnetic signals over a range of frequencies.

12. The system of claim 1, further comprising:

a second receiving antenna;

a signal combiner configured to accept a plurality of electromagnetic signals over a frequency range, applied to a plurality of input ports thereof, and further configured to provide a single output signal substantially inclusive of the input signal content, on an output port thereof; and

a plurality of interconnecting signal lines that establish connectivity between the respective receiving antennas and the respective signal combiner input ports, and between the combiner output port and the transmitting antenna.

13. The system of claim 1, further comprising:

a second transmitting antenna;

a signal splitter, configured to accept an electromagnetic signal over a frequency range, applied to an input port thereof, and further configured to provide a plurality of output signals, substantially inclusive of the input signal content, on a plurality of output ports thereof; and

a plurality of interconnecting signal lines that establish connectivity between the receiving antenna and the signal splitter input port, and between the respective splitter output ports and the respective transmitting antennas.

14. The system of claim 1, wherein the transmitting antenna further comprises a bay wherein four dipoles have quasi-helical orientation and approximate fourfold rotational symmetry with reference to a common vertical axis.

15. The system of claim 1, wherein the transmitting antenna further comprises:

a coupling body, wherein the coupling body further comprises an input port; and

a manifold feed plate, wherein the manifold feed plate further comprises;

a central node configured to connect via the coupling body to an interconnecting signal line;

a plurality of feed blades whereby signals are distributed from the central node to a plurality of dipole feed points; and

a plurality of tuning paddles connected to the respective feed blades, wherein the tuning paddle orientations and dimensions determine transmitting antenna impedance, at least in part, with reference to the coupling body input port.

16. A system for rebroadcasting a source signal originating from a location external to the system, comprising:

means for receiving an electromagnetic signal from a broadcast radio transmission, wherein the means for receiving has elliptical polarization with a first handedness;

means for retransmitting an electromagnetic signal from a broadcast radio transmission, wherein the means for retransmitting has elliptical polarization with a second handedness, opposite to the handedness of the means for receiving; and

means for coupling a signal from the means for receiving to the means for retransmitting.

17. The system for rebroadcasting of claim 16, further comprising means for controlling signal characteristics, interposed between the means for receiving and the means for retransmitting, wherein the means for controlling signal characteristics comprises:

means for accepting a received signal supplied from the means for receiving;

means for supplying an output signal for application to the means for retransmitting;

means for adjusting relative amplitudes of a plurality of component frequencies of the received signal;

means for adjusting relative phase between a plurality of component frequencies of the received signal;

means for increasing output signal power with reference to received signal power; and

means for regulating output signal power, as supplied to the means for retransmitting, with reference to received signal power.

18. The system for rebroadcasting within a structure of claim 16, wherein the means for retransmitting further comprises:

means for accepting a signal to be retransmitted;

means for distributing energy of an accepted signal to a plurality of spatially discrete emitters with substantially equal magnitude and phase, wherein the emitters are positioned with rotational symmetry with reference to a reference axis of the means for accepting a signal;

means for terminating a plurality of emitters, wherein the means for terminating cause the means for accepting a signal to exhibit a substantially nonreactive net impedance; and

means for propagating distributed signal energy in the form of electromagnetic radiation from a like plurality of discrete locations, wherein the electromagnetic radiation exhibits elliptical polarization with a specified axial ratio.

19. The system for rebroadcasting within a structure of claim 16, wherein the means for retransmitting further comprises means for concealing the means for retransmitting from view at least in part, wherein the means for concealing introduces less than 3 dB of attenuation of the retransmitted broadcast radio signal.

20. A method for rebroadcasting a source signal originating from a location external to the system, comprising:

receiving an electromagnetic signal from a broadcast radio transmission having a first handedness of elliptical polarization;

transferring the signal to an amplifier, wherein the amplifier performs the steps of;

accepting the signal;

attenuating out-of-band signal energy;

adjusting relative phase of in-band signal frequency components;

increasing overall signal power;

regulating overall signal power; and

furnishing the amplified signal for retransmission;

applying the received and amplified signal to a radio signal emitter having a second handedness of elliptical polarization; and

coupling the signal from the emitter to a surrounding region.

21. The method for rebroadcasting within a structure of claim 20, wherein applying the received and amplified signal to the radio signal emitter further comprises:

establishing n arcuate dipoles disposed with approximate n-fold rotational symmetry and quasi-helical orientation about a vertical axis;

interconnecting midpoints of the respective dipoles at a reference potential common to the received and amplified signal;

distributing the received and amplified signal to the arcuate dipoles at feed points distal to the midpoints of the respective dipoles; and

providing impedance cancellation proximal to the feed points using tuning paddles.

22. The method for rebroadcasting within a structure of claim 21, wherein establishing n arcuate dipoles further comprises:

cutting a conductive material to form m components having p dipoles each, wherein m is an integer number of components, p is an integer number of dipoles per component, and n is the number of dipoles; and

conductively stacking the components with rotational symmetry of position.