Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
  • H01Q9/04—Resonant antennas
  • H01Q9/30—Resonant antennas with feed to end of elongated active element, e.g. unipole
  • H01Q9/42—Resonant antennas with feed to end of elongated active element, e.g. unipole with folded element, the folded parts being spaced apart a small fraction of the operating wavelength
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
  • G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
  • G01S3/14—Systems for determining direction or deviation from predetermined direction
  • G01S3/16—Systems for determining direction or deviation from predetermined direction using amplitude comparison of signals derived sequentially from receiving antennas or antenna systems having differently-oriented directivity characteristics or from an antenna system having periodically-varied orientation of directivity characteristic
  • G01S3/18—Systems for determining direction or deviation from predetermined direction using amplitude comparison of signals derived sequentially from receiving antennas or antenna systems having differently-oriented directivity characteristics or from an antenna system having periodically-varied orientation of directivity characteristic derived directly from separate directional antennas
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
  • G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
  • G01S3/14—Systems for determining direction or deviation from predetermined direction
  • G01S3/38—Systems for determining direction or deviation from predetermined direction using adjustment of real or effective orientation of directivity characteristic of an antenna or an antenna system to give a desired condition of signal derived from that antenna or antenna system, e.g. to give a maximum or minimum signal
  • G01S3/40—Systems for determining direction or deviation from predetermined direction using adjustment of real or effective orientation of directivity characteristic of an antenna or an antenna system to give a desired condition of signal derived from that antenna or antenna system, e.g. to give a maximum or minimum signal adjusting orientation of a single directivity characteristic to produce maximum or minimum signal, e.g. rotatable loop antenna or equivalent goniometer system
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/29—Combinations of different interacting antenna units for giving a desired directional characteristic
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
  • G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
  • G01S3/04—Details
  • G01S3/043—Receivers
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
  • G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
  • G01S3/04—Details
  • G01S3/046—Displays or indicators

Definitions

• the present disclosure is directed to direction finding antenna systems and, more specifically, to direction finding antenna systems employing a plurality of antennas.
• PCB patch antenna includes a radiating portion that is disposed on a layer of a PCB and a ground plane that is disposed on another layer either above or below the radiating portion (where "above” and “below” refer to positions in the stack of layers). Since the radiating portion of a patch antenna utilizes the ground plane, it is called a grounded antenna. Other antenna elements are not oriented above or below a ground plane and are referred to as ungrounded antennas.
• a Planar Inverted F Antenna (PIFA) can be made from some patch antennas by shorting an end of a patch element to ground. Many antenna elements are associated with parasitic elements to change a pattern and/or add frequency bands to the antenna' s operational spectrum.
• Direction finding antenna systems include finding sources of Radio Frequency (RF) interference (sometimes called “electromagnetic interference” or “EMI”) or finding beacons.
• RF Radio Frequency
• the prior art includes some designs for indicating a direction of a Radio Frequency (RF) beacon.
• RF Radio Frequency
• Prior art direction-finding antennas use one of two technologies.
• the first technology is a highly directive antenna beam, such as that produced by a Yagi antenna or a phased array.
• a highly directive antenna beam can sometimes give a good indication about the direction of an RF beacon.
• Highly directive antenna systems are often large and unwieldy, thereby causing them to be unfit for portable or casual use.
• the other technology that is employed in current direction finding antenna systems includes calculating a signal strength difference in two antenna beams.
• One antenna beam is substantially uniform in all azimuthal directions, whereas the other antenna beam includes a plurality of nulls.
• An example prior art system includes a dipole and a slot antenna placed on a PCB. When a beacon is along an azimuth with a null, the signal strength difference between the uniform beam and the beam with the null is large, thereby giving an indication of direction.
• multiple nulls means that there is more than one azimuthal direction that shows a large signal strength difference.
• the nulls are 180 degrees apart, so that a large signal strength difference either means a user is directed in the right direction or exactly in the wrong direction.
• Various embodiments of the present invention are directed to a systems and methods which include at least two antenna elements providing a first and second antenna patterns, the antenna elements configured such that the greatest difference in received signal strength of the two antenna patterns occurs at a null of one of the antenna patterns.
• a system includes an antenna A and an antenna B.
• a third element is configures to act as a parasitic element for antenna A and as a reflector for antenna B.
• Antennas A and B and the third element are arranged so that antenna B has a substantially omnidirectional pattern, whereas antenna A has a cardioid pattern with one null.
• An RF circuit receives signals from the antennas and compares the signal strengths. The azimuthal direction that shows the greatest difference signal strength can also be considered the direction of a signal.
• the antenna elements can be any of a variety of antennas, such as PIFAs, patches, monopoles, helixes, horns and the like.
• the antenna elements (including the third element) can be grounded or ungrounded, shorted to ground or floating.
• FIGURE 1 is an illustration of an exemplary antenna system adapted according to one embodiment of the invention
• FIGURE 2 is an illustration of exemplary antenna patterns associated with the respective antennas of FIGURE 1;
• FIGURE 3 is an illustration of an exemplary antenna system, adapted according to one embodiment of the invention.
• FIGURE 4 is an illustration of antenna patterns for the antenna elements of FIGURE 3 at various points in the operating band
• FIGURE 5 is an illustration of an exemplary antenna system adapted according to one embodiment of the invention.
• FIGURE 6 is an illustration of an exemplary antenna system adapted according to one embodiment of the invention.
• FIGURE 7 is an illustration of an exemplary antenna system adapted according to one embodiment of the invention.
• FIGURE 8 is an illustration of an exemplary antenna system adapted according to one embodiment of the invention.
• FIGURE 9 is an illustration of an exemplary antenna system adapted according to one embodiment of the invention.
• FIGURE 10 is an illustration of an exemplary antenna system adapted according to one embodiment of the invention.
• FIGURE 11 is an illustration of an exemplary antenna system adapted according to one embodiment of the invention.
• FIGURE 12 is an illustration of an exemplary method adapted according to one embodiment of the invention.
• FIGURE 1 is an illustration of exemplary antenna system 100 adapted according to one embodiment of the invention.
• Antenna system 100 includes two antenna elements 102 and 103. Between antenna elements 102 and 103 is parasitic element 104, and also there is switch 105 that is used to select signals from one antenna element 102/103 at a time.
• the various components are disposed on PCB 101, which also hosts ground plane 106 on a lower layer, the outline of which is indicated by a dashed line.
• Parasitic element 104 is disposed so as to provide an RF trap on antenna 103, thereby creating a single null on the direction of a line between the parasitic element and antenna 103.
• System 100 also includes RF module 106 in communication with switch 105 to receive the signals from antennas 102 and 103.
• RF module 106 has a control circuit operating switch 105 to switch between receiving the signals of antenna 102 and antenna 103. Switch 105 alternatingly feeds signals from antennas 102 and 103 to RF module 106.
• RF module 106 is in communication with computing circuit 107, which compares the strengths of the respective signals from antennas 102 and 103.
• Computing circuit 107 outputs an indication of direction (derived from comparing signal strengths) to, e.g., a user interface (not shown).
• RF module 106 includes a Received Signal Strength Indicator (RSSI).
• RSSI Received Signal Strength Indicator
• antenna system 100 is a grounded antenna system.
• Other embodiments may move any one or more of antenna elements 102 and 103 (and also parasitic element 104) away from the ground plane, thereby making an ungrounded antenna system.
• FIGURE 2 is an illustration of exemplary antenna patterns 201 and 202 associated with antennas 102 and 103 (of FIGURE 1), respectively.
• pattern 202 includes a null between thirty and sixty degrees, while pattern 201 is substantially uniform in all azimuthal directions.
• a computing circuit such as circuit 107 of FIGURE 1, compares the signal strengths and outputs an indication of the comparison.
• FIGURE 3 is an illustration of exemplary antenna system 300, adapted according to one embodiment of the invention.
• Antenna system 300 includes ground plane 301, antenna elements 303 and 304, as well as parasitic element 305 disposed on Printed Circuit Board (PCB) 302.
• PCB Printed Circuit Board
• the conductive portions are made of copper; however, other conductors can be used. Substrates other than PCBs can be used as well.
• Parasitic element 305 is parasitic with respect to antenna element 304 and acts as a reflector with respect to antenna element 303.
• Antenna elements 303 and 304 and parasitic element 305 are configured such that the greatest signal strength difference between antenna elements 303 and 304 occurs at an azimuthal direction corresponding to a null of antenna element 304.
• some embodiments of system 300 also include an RF module such that the RF module receives signals alternatingly from antenna elements 303 and 304.
• Suitable switches include those made from pin diodes, transistors, integrated circuits, manual switches, and the like.
• Various embodiments provide a signal from each antenna to the RF circuit at least once each time the user orients the direction-finding device to a direction. Some embodiments provide for periodic switching, such as at five Hertz, ten Hertz, or the like. Other embodiments of the invention may omit the switch and instead provide for two RF inputs to the RF module.
• FIGURE 3 includes dimensions and is drawn to scale.
• System 300 is operable in the band from 2.4 GHz to 2.48 GHz. While the dimensions of system 300 are given, it should be noted that not all embodiments of the invention are so limited. For instance, antenna systems can typically be scaled to work at different operating bands, and the same is true for system 300 (as well as for system 100 of FIGURE 1). In fact, embodiments of the invention can be created for any RF band.
• antenna elements, ground planes, and parasitic elements can differ from that shown in FIGURES 1 and 3.
• antenna elements and parasitic elements can be chosen from a variety of forms, such as monopoles, helixes, PIFAs, loops, horns, and the like. Any or all of the elements can be grounded or ungrounded, shorted to ground or not shorted to ground (i.e., floating).
• FIGURE 4 is an illustration of antenna patterns for antenna elements 303 and 304 of FIGURE 3 at various points in the operating band.
• the greatest difference between the signal strengths is at the azimuth that includes null 401 of antenna element 304 (i.e., about OdB from antenna 303 compared to about -15dB from antenna 304 at the azimuth of null 401).
• Antenna element 303 also has null 402, but the difference between the signal strengths at that azimuth is less than at the azimuth of null 401 (i.e., less than the 15dB difference at null 401).
• the value of the difference at null 401 is around +15dB (i.e.
• FIGURE 5 is an illustration of exemplary antenna system 500 adapted according to one embodiment of the invention.
• Antenna system 500 is somewhat similar in structure to system 300 of FIGURE 3, but is not to scale and is more generalized for illustrative purposes.
• System 500 includes ground plane 501 disposed on substrate 502.
• System 500 also includes PIFA antenna elements 503 and 504, as well as parasitic element 505.
• Switch 506 operates to supply the signals from antenna elements 503 and 504 alternatingly to module 507 that receives the signals and compares signal strengths. As with any of the embodiments shown herein the design may omit switch 506 and use a two-input RF module instead.
• Blocks 510 are conceptual and illustrate that any one or more of elements SOS- SOS can be shorted to ground or floating.
• the operating frequency of system 500 can be changed by modifying the effective radiating lengths of elements 503 and 504.
• the azimuthal direction of the null of antenna element 505 can be tuned by modifying the saw tooth structure of parasitic element 505.
• the lengths of protrusions 505a-d affect the direction of the null, such that the lengths of protrusions 505a-d can be designed to give a desired null direction.
• Antenna element 503 sees element 505 not as a parasitic element, but as a reflector.
• antenna element 503 and element 505 are configured within system 500 so that the electric field on antenna element 503 is highest at points furthest from element 505.
• FIGURE 6 is an illustration of exemplary system 600 adapted according to one embodiment of the invention.
• System 600 is similar to system 500 of FIGURE 5, with the addition of slots 601-605.
• Slots 601-605 are used in this example to provide matching between switching circuit 506 and antenna elements 503 and 504. Slots 601-605 also fine tune the operating band of system 600.
• FIGURE 7 is an illustration of exemplary system 700 adapted according to one embodiment of the invention.
• System 700 is similar to system 500 of FIGURE 5 with the addition of notches 701-703.
• Notches 701-703 are used in system 700 to suppress mutual coupling between elements 503 and 504 and to shape the patterns of antenna elements 503 and 504.
• Other embodiments use notches to create additional operating bands and/or fine tune operating bands.
• FIGURE 8 is an illustration of exemplary system 800 adapted according to one embodiment of the invention.
• System 800 adds strips 801-803.
• additional strips 801-803 are used for pattern shaping and impedance matching.
• additional strips add operating bands to antenna systems.
• FIGURE 9 is an illustration of exemplary system 900 adapted according to one embodiment of the invention.
• System 900 employs additional parasitic elements 901 and 902.
• Parasitic elements 901 and 902 provide pattern shaping, impedance matching, and/or additional operating bands.
• Parasitic elements 901 and 902 are shown shorted to ground, but in other embodiments can be floating.
• FIGURE 10 is an illustration of exemplary system 1000 adapted according to one embodiment of the invention.
• System 1000 illustrates that a given embodiment can incorporate one or more of slots, notches, additional strips, and additional parasitic elements.
• FIGURE 11 is an illustration of exemplary system 1100 adapted according to one embodiment of the invention.
• System 1100 is an example consumer device that employs one or more antenna systems, such as the systems described above with respect to FIGURES 1- 10. In this example, system 1100 is small enough for a consumer to carry in a pocket and/or attach to a key chain.
• System 1100 includes housing 1105, which conceals and protects the antenna system (not shown), and which hosts keychain attaching mechanism 106.
• Activation button 1101 turns system 1100 on and begins the process of receiving signals and comparing signal strengths. As the difference in receive signal strength increases, lights 1102-1104 are successively illuminated. When all three lights 1102-1104 are illuminated, a human user has a reliable indication of direction to a beacon (not shown).
• FIGURE 12 is an illustration of exemplary method 1200 adapted according to one embodiment of the invention. Method 1200 may be performed, for example, by a device employing one or more of the systems described above.
• step 1201 a signal is received from a transmitter using a pattern of the first antenna element.
• step 1202 a signal is received from the transmitter using a pattern of the second antenna element.
• the greatest difference in gain between the patterns of the first and second antenna elements occurs at an azimuth of a null of the first antenna element's pattern.
• the difference in gain is a known value, as is the azimuth angle of the null of the first antenna.
• a difference in received signal strengths of the first and second antennas is ascertained.
• an RSSI can be used to ascertain the signal strengths.
• the transmitter is at the same azimuth angle as the null of the first antenna pattern.
• an indication of direction is output and is based, at least in part, upon the compared received signal strengths. For example, an analog signal that is proportional to the difference in received signal strengths can be output to computing circuitry that logically calculates how close the direction is to the azimuth of the null. Indications of direction can be fed to a User Interface (UI). For instance, a user interface (such as lights 1102-1104 of FIGURE 11) can indicate whether the direction is close (and/or getting closer) or far (and/or getting farther) from the azimuth of the transmitter. In the consumer device shown as system 1100 in FIGURE 11, a signal strength difference corresponding to the azimuth angle with the greatest gain difference causes all three lights to light up.
• UI User Interface
• steps 1201 and 1202 are performed at the same time. In other embodiment, such as those that switch between the inputs of the antennas, steps 1201 and 1202 are repeated alternatingly.
• beacons can be placed on children or pets, allowing a parent or pet owner to more quickly locate the child or pet when visual contact is lost.
• a beacon can be placed in a car so that the car's owner can locate the car in a crowded or large parking area.
• Various embodiments can also be used to locate EMI sources and jammers.
• embodiments of the invention provide one or more advantages over prior art systems. For example, embodiments that include patterns with one null provide more certain indications than do systems that employ patterns with two or more nulls. Furthermore, embodiments of the invention can be made to be more compact than more highly-directive systems that employ, e.g., Yagi antennas or phased arrays.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Variable-Direction Aerials And Aerial Arrays (AREA)

Priority Applications (2)

Applications Claiming Priority (1)

Publications (1)

Family

ID=41124210

Family Applications (1)

Country Status (2)

Cited By (1)

Families Citing this family (3)

Citations (4)

Family Cites Families (3)

• 2008
  • 2008-07-18 WO PCT/CN2008/071689 patent/WO2010006484A1/en active Application Filing
  • 2008-07-18 CN CN200880000083.7A patent/CN101542839B/zh not_active Expired - Fee Related

Patent Citations (4)

Also Published As

Similar Documents

Legal Events