GPS navigation and differential-correction beacon antenna combination

• US 5,568,162 A
• Filed: 08/08/1994
• Issued: 10/22/1996
• Est. Priority Date: 08/08/1994
• Status: Expired due to Fees

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Samsel, Robert A., Westfall, Brian G., Will, Stephen K.
• Primary Examiner(s): Le, Hoanganh
• Application Number:
  US08/287,188
• Time in Patent Office: 806 Days
• Field of Search: 343/842, 343/841, 343/787, 343/788, 343/725, 343/726, 343/727, 343/728, 343/729, 343/730
• US Class Current: 343/842
• CPC Class Codes: H01Q 1/526 Electromagnetic shields
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H01Q 7/04 Screened antennas H01Q7/02, H01Q7/06 take precedence
• CPC Class Codes: H01Q 9/0407 Substantially flat resonant element parallel to ground plane, e.g. patch antenna dipole H01Q9/285; monopole H01Q9/40

Abstract

An antenna system comprises a stack of elements that include a GPS patch antenna on a groundplane with an associated low-noise amplifier (LNA), a first Faraday shield of flat ribbon cable covering a first ferrite rod magnetic field antenna, a second ferrite rod magnetic field antenna separated from and orthogonal to the first ferrite rod magnetic field antenna, a second Faraday shield of flat ribbon cable covering the second ferrite rod magnetic field antenna and having a LNA for each of the ferrite rod magnetic field antennas. A third Faraday shield is positioned between the first and second ferrite rod magnetic field antennas. All the Faraday shields are connected to ground such that there are no loops that may act as shorted turns to avoid desensitizing the ferrite rod magnetic field antennas.

Claims

1. An antenna system, comprising:

a microwave receiver antenna for receiving microwave radio transmissions from orbiting global positioning system (GPS) satellites and for connection to a GPS navigation receiver;

magnetic loop antenna means for connection to said GPS navigation receiver, and proximate to the microwave receiver antenna, and for receiving radio beacon transmissions that include differential correction information;

a radome providing for the enclosure and protection from weather and mechanical injury of the microwave receiver antenna and the magnetic loop antenna means disposed within, wherein the radome is comprised of material transparent to microwave radio signals and the relative placement of the microwave receiver antenna and the magnetic loop antenna means within the radome provides for a view of the sky by the microwave receiver antenna that is unobstructed by the magnetic loop antenna means; and

radio electrostatic field shielding means comprising a plurality of similarly-oriented conductors that surround the magnetic loop antenna means where each of said conductors is open-ended and has a single connection to ground, wherein parasitic currents that would otherwise desensitize the magnetic loop antenna are prevented by open-ending said conductors.

2. An antenna system, comprising:

a microwave receiver antenna for receiving microwave radio transmissions from orbiting global positioning system (GPS) satellites and for connection to a GPS navigation receiver;

magnetic loop antenna means for connection to said GPS navigation receiver, and proximate to the microwave receiver antenna, and for receiving radio beacon transmissions that include differential correction information; and

radio electrostatic field shielding means comprising a plurality of similarly-oriented conductors that surround the magnetic loop antenna means where each of said conductors is open-ended and has a single connection to ground, wherein parasitic currents that would otherwise desensitize the magnetic loop antenna are prevented by open-ending said conductors;

wherein, the microwave receiver antenna is oriented in an enclosure for upward vertical hemispherical radio signal reception; and

wherein, the magnetic loop antenna means comprises a pair of ferrite rods mounted at right angles to one another and mounted beneath the microwave receiver antenna in said enclosure for horizontal omni-directional radio signal reception.

3. An antenna system, comprising:

a microwave receiver antenna for receiving microwave radio transmissions from orbiting global positioning system (GPS) satellites and for connection to a GPS navigation receiver;

magnetic loop antenna means for connection to said GPS navigation receiver, and proximate to the microwave receiver antenna, and for receiving radio beacon transmissions that include differential correction information; and

radio electrostatic field shielding means comprising a plurality of similarly-oriented conductors that surround the magnetic loop antenna means where each of said conductors is open-ended and has a single connection to ground, wherein parasitic currents that would otherwise desensitize the magnetic loop antenna are prevented by open-ending said conductors;

wherein, the magnetic loop antenna means comprises two ferrite rods set at right angles to one another; and

wherein, the radio electrostatic field shielding means comprises a plurality of conductors in a fan arrangement each positioned above, below and between said ferrite rods and spaced away from the magnetic loop antenna means to reduce antenna desensitization.

4. The antenna system of claim 3, wherein:

the radio electrostatic field shielding means comprises a flat ribbon conductor wrapped around the magnetic loop antenna means.

5. The antenna system of claim 3, wherein:

the radio electrostatic field shielding means comprises a flat ribbon conductor wrapped around the circumference of each of said ferrite rods with a spacing to reduce antenna desensitization and folded over an end of each of said ferrite rods.

6. An antenna system, comprising:

a microwave receiver antenna for receiving microwave radio transmissions from orbiting global positioning system (GPS) satellites and for connection to a GPS navigation receiver;

magnetic loop antenna means for connection to said GPS navigation receiver, and proximate to the microwave receiver antenna, and for receiving radio beacon transmissions that include differential correction information; and

radio electrostatic field shielding means comprising a plurality of similarly-oriented conductors that surround the magnetic loop antenna means where each of said conductors is open-ended and has a single connection to ground, wherein parasitic currents that would otherwise desensitize the magnetic loop antenna are prevented by open-ending said conductors;

wherein, the magnetic loop antenna means comprises two ferrite rods set at right angles to one another with a set of three plates with one each plate positioned above, between and below said ferrite rods; and

wherein, the radio electrostatic field shielding means comprises a flat ribbon conductor laid flat against each of said plates and spaced away from the magnetic loop antenna means to reduce antenna desensitization and having ends of said flat ribbon conductor folded over an end of each of said ferrite rods to embrace at least two of said plates.