July 2004 doc IEEE 802 15 040360 r

July 2004 doc: IEEE 802. 15 -04/0360 r 0 Project: IEEE P 802. 15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Near Filed Electromagnetic Ranging] Date Submitted: [13 July, 2004] Source: [Kazimierz “Kai” Siwiak] Company [Time. Derivative, Inc. ] Address [10988 NW 14 th Street, Coral Springs, FL, USA] Voice: [+1 -954 -937 -3288], FAX: [--], E-Mail: [k. siwiak@ieee. org] Re: [ranging] Abstract: [Range determination does not require bandwidth, it can be done using near-field antenna techniques. Full 3 -d location can be determined between one ‘sensor’ and one target using distance and relative angle techniques. ] Purpose: [Range determination can be accomplished using many techniques involving timing of signals. Accuracies of the timing methods are related to signal bandwidth. This material is intended to inform P 802. 15. 4 a about a distance determination technique involving predictable near-field antenna fields. When combined with phase-monopulse angle determination, full 3 -d location is possible ] Notice: This document has been prepared to assist the IEEE P 802. 15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P 802. 15. Submission 1 K. Siwiak, Time. Derivative, Inc.

July 2004 doc: IEEE 802. 15 -04/0360 r 0 Location Using Near Field Techniques K. Siwiak, Time. Derivative, Inc. Submission 2 K. Siwiak, Time. Derivative, Inc.

July 2004 doc: IEEE 802. 15 -04/0360 r 0 Location Doesn’t Need Bandwidth • Distance measurements do not “need” large bandwidths • Accuracies of centimeters are possible at Very Low Frequencies • “Time” is not the only parameter to carry “distance” information • Low frequency near-field techniques may be employed: Near Field EM Ranging Submission 3 K. Siwiak, Time. Derivative, Inc.

July 2004 doc: IEEE 802. 15 -04/0360 r 0 Small Loop E and H Fields Far field terms: 0 deg phase difference Submission Near field terms: 90 deg phase difference 4 K. Siwiak, Time. Derivative, Inc.

July 2004 doc: IEEE 802. 15 -04/0360 r 0 E and H Near Field Tracking • Electric and Magnetic fields 90 deg out of phase in the near field; in-phase far away • Phase difference varies predictably from 90 deg at antenna to 0 deg in “far” zone • Good transition region between 0. 05 and 0. 4 wavelengths for accurate distance tracking Submission 5 K. Siwiak, Time. Derivative, Inc.

July 2004 doc: IEEE 802. 15 -04/0360 r 0 Basis of Near-Field Tracking 90 phase, degrees 75 H-field Phase 60 E-field Phase 45 30 15 Phase difference 0 0 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 distance, wavelengths Based on: “Technical Introduction to Near Field Tracking, ” (Online): <http: //www. q-track. com> Q-Track Corp. , 2003. Submission 6 K. Siwiak, Time. Derivative, Inc.

July 2004 doc: IEEE 802. 15 -04/0360 r 0 Phase Difference Yields Distance Range(l) TX 0. 05 Beacon Locator 0. 05 l Range(l) TX 0. 50 Beacon Locator 0. 50 l Submission 7 K. Siwiak, Time. Derivative, Inc.

July 2004 doc: IEEE 802. 15 -04/0360 r 0 Near Field Tracking Accuracy Error, m 1 0. 1 1. 295 MHz system measured mean value 0. 01 0. 001 0 10 20 30 40 50 60 70 Range, m 80 90 100 110 120 Data Courtesy of: Q-Track Corporation Submission 8 K. Siwiak, Time. Derivative, Inc.

July 2004 doc: IEEE 802. 15 -04/0360 r 0 Can Be Used with Phase Monopulse Techniques for Location • The relative angle f to a signal can be found by signals “a” and “b” form two closely spaced antennas “A” and “B” • Arithmetic network used to form “a+b” and “a-b” signals • The ratio (a-b)/(a+b) is proportional to angle f • Technique is called “phase monopulse” and was associated with tracking systems over the past 40 years or so • Four antennas (elevation and azimuth phase monopulse gives angle in two dimensions! Submission 9 K. Siwiak, Time. Derivative, Inc.

July 2004 doc: IEEE 802. 15 -04/0360 r 0 Azimuth Monopulse Tracking with Near Field Ranging H-field: f found from phase monopulse on Ea , Eb emitting target “a” E-field: “b” r found from E, H phase Can do similar phase monopulse in azimuth and elevation for full three dimensional LOCATION Submission 10 K. Siwiak, Time. Derivative, Inc.

July 2004 doc: IEEE 802. 15 -04/0360 r 0 Summary / Conclusions • The phase difference between E and H fields directly relates to distance • Phase difference in the range 0. 05 to 0. 4 wavelengths is suitable for accurate distance (r) measurements • Requires just a sinusoidal signal • Can be used with angle determination (in one or two planes) to get location coordinates: (r, f) Submission 11 K. Siwiak, Time. Derivative, Inc.

July 2004 doc: IEEE 802. 15 -04/0360 r 0 Resources and Information • Q-Track: http: //www. q-track. com Submission 12 K. Siwiak, Time. Derivative, Inc.