# US 9,520,052 B2 · Security tag system with improved range consistency > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,520,052 B2 - Document ID: US9520052B2 - Status: Granted - Kind: B2 - Application number: 14/687,299 - Filed: 2015-04-15 - Published: 2016-10-20 - Granted: 2016-12-13 - Earliest claimed: 2015-04-15 - Assignees: Innovative Control Systems, Inc. - Applicants: Innovative Control Systems, Inc. - Inventors: James F. Stoffer; Mark Kiekhefer; Chris Hielsberg; Jason Guerrero - Web page: https://patentgrep.com/patent/US9520052B2 ## CPC - G08B 25/10: using wireless transmission systems {(G08B25/009 takes precedence)} - G06K 7/10346: {the antenna being of the far field type, e.g. HF types or dipoles} - G06K 7/10356: {using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas} - G06K 7/10366: {the interrogation device being adapted for miscellaneous applications} - G06K 7/10415: {the interrogation device being fixed in its position, such as an access control device for reading wireless access cards, or a wireless ATM (banking machines in general G07F19/00)} - G08B: SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS - G06K: GRAPHICAL DATA READING (image or video recognition or understanding G06V); PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS ## Abstract A radio transmitter used to transmit an activation signal for radio tags held by individuals or the like provides multi-dimensional polarization to an activation signal so as to allow more consistent range detection of an individual with a tag having a single axis of sensitivity. Circular or spherical polarization can be obtained using the system which may include an antenna design permitting decoupling of antennas necessary for the polarization, a quadrature locking system simplifying proper phase control of the necessary signals and a system for tuning the same. ## Claims ### Claim 1 A control unit for a wirelessly activated security tag comprising: a first and second antenna having mutually perpendicular first and second transmission axes respectively; a first radiofrequency amplifier communicating with the first antenna to provide a first activation signal at a first center frequency; a second radiofrequency amplifier communicating with the second antenna to provide a second activation signal at the first center frequency and having a 90 degrees phase shift with respect to the first activation signal; and including a third antenna orthogonal to the first and second antennas and a third radiofrequency amplifier communicating with the third antenna to provide a third activation signal deviating from the first center frequency to provide a varying phase shift with respect to the first and second activation signals; a radiofrequency receiver for receiving an identification signal from a security tag activated by one of the first, second and third activation signals to provide an output control signal; further including a microprocessor for controlling the first, second, and third radiofrequency amplifiers to vary a power output provided by each of the first second, and third amplifiers to modulate an activation region and to monitor the radiofrequency receiver for receiving an identification signal from the security tag from at least two different power outputs provided to each of the first, second, and third amplifiers to deduce a range of an activated security tag. ### Claim 2 (depends on 1) The control unit of claim 1 further including a lockable pivot supporting the first antenna to allow it to pivot about an axis perpendicular to the first and second transmission axes when unlocked and to be retained against pivoting in a locked state. ### Claim 3 (depends on 1) The control unit of claim 1 further including a visual indicator circuit discriminating among variations in electrical energy induced in the first antenna from the second antenna. ### Claim 4 (depends on 3) The control unit of claim 3 wherein the visual indicator circuit further discriminates among variations in electrical energy induced in the first antenna from the first radiofrequency amplifier. ### Claim 5 (depends on 4) The control unit of claim 4 further including an additional visual indicator circuit further discriminating among variations in electrical energy induced in the second antenna from the second radiofrequency amplifier. ### Claim 6 (depends on 1) The control unit of claim 1 wherein the first and second antennas are solenoids providing windings about respective transmission axes. ### Claim 7 The control unit of claim l further including a radiofrequency oscillator communicating with the first and second radiofrequency amplifiers and further including a phase comparator comparing phases of signals of the first and second antennas to detect a deviation from a 90 degrees phase relationship and to dynamically adjust the phase of at least one signal from the radiofrequency oscillator to the first and second radiofrequency amplifier to hold a phase of the signals of the first and second antennas at a phase difference of 90 degrees. ### Claim 8 (depends on 7) The control unit of claim 7 wherein the radiofrequency oscillator communicates with the first and second radiofrequency amplifier through a first and second phase shift adjuster and wherein the phase comparator communicates with the first and second phase shift adjuster to provide for the adjustment of either of the phases of the signals of the first and second antennas. ### Claim 9 (depends on 1) The control unit of claim 1 wherein the third activation signal is frequency modulated at a modulating frequency at least 100 times less than the first center frequency. ### Claim 10 (depends on 9) The control unit of claim 9 further including a lockable pivot supporting the third antenna to allow it to pivot about a first pivot axis parallel with the first transmission axis and a second pivot axis parallel to the second transmission axis. ### Claim 11 (depends on 10) The control unit of claim 10 wherein the third antenna is a printed circuit board having multiple layers implementing a set of windings about an axis perpendicular to a broad face of the printed circuit board. ### Claim 12 (depends on 1) The control unit of claim 1 further including visual indicator indicating electrical energy induced in the third antenna from at least one of the first and second antennas. ### Claim 13 (depends on 12) The control unit of claim 12 wherein the visual indicator circuit further discriminates among variations in electrical energy induced in the third antenna from the third radiofrequency amplifier. ### Claim 14 (depends on 1) The control unit of claim 1 further including a radiofrequency oscillator communicating with the third radiofrequency amplifier and further including a phase lock loop providing a phase comparator and a voltage controlled oscillator, the latter providing an output to the third radiofrequency amplifier frequency loosely locked to the radiofrequency oscillator. ### Claim 15 (depends on 14) The control unit of claim 14 wherein the phase lock loop includes a phase comparator and a voltage controlled oscillator and further includes a summing junction summing a phase modulation signal to the output of the phase comparator. ### Claim 16 (depends on 15) The control unit of claim 15 wherein the phase modulation signal has a frequency of at least 100 times less than the first center frequency.