Browse Prior Art Database

Near Field Communication System

IP.com Disclosure Number: IPCOM000077606D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Smith, AA: AUTHOR

Abstract

This system is arranged to transmit data, via an electromagnetic field, from one point to another in the near vicinity. It uses such a low radiated field intensity level that the signal is below the ambient noise level and is thus undetectable using ordinary antennas. Thus it will not cause interference to communications devices or electronic data processing equipments or the like.

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Near Field Communication System

This system is arranged to transmit data, via an electromagnetic field, from one point to another in the near vicinity. It uses such a low radiated field intensity level that the signal is below the ambient noise level and is thus undetectable using ordinary antennas. Thus it will not cause interference to communications devices or electronic data processing equipments or the like.

The near field communication system consists of a transmitter, a transmitting antenna, a differential receiving antenna system, and a receiver. The receiving antenna is a two-element array, and the elements are connected through a subtraction device to the receiver. The subtraction device yields the difference between the two antenna outputs.

In operation, the electrical distance r/lambda should be less than approximately 0.1 where lambda is the center frequency wave length at which the system operates. The ratio d/r should also be less than approximately 0.1. The transmitter power is then adjusted for the required received signal-to- ambient noise ratio at the input to the receiver. This transmitter power is less than the power which would be required if an ordinary single element receiving antenna were used by a factor of approximately (0.276 B over r/lambda)/2/, where B = ground wave attenuation rate of the signal field.

This system utilizes the theoretical and empirical results set forth in a paper by the author entitled "Reception of Nonhomogeneous...