How Radio Frequency Identification (RFID) Tags Were Invented
A 1970 patent describing a remote tag that powers itself using incoming radio signals to read and write data, forming the foundation of modern RFID technology.
Original patent title: “Transponder apparatus and system”
A 1970 patent describing a remote tag that powers itself using incoming radio signals to read and write data, forming the foundation of modern RFID technology. Granted to Communications Services Corp Inc in 1973 with 9 claims and 185 forward citations, and it is now in the public domain.
Coverage
What does this patent actually cover?
This patent describes a transponder that acts as a remote data storage device. It uses an incoming signal from a base station to wake up, power its internal circuits, and either read or write data to its memory. Once the data is processed, the device sends an answerback signal back to the base station. By harvesting energy directly from the interrogation signal, the device eliminates the need for an internal battery, making it entirely self-contained.
The gap
What does this patent NOT cover?
- Does not cover active transponders that rely on internal batteries for their primary power source.
- Does not cover systems where the base station does not provide the energy for the transponder's operation.
- Does not cover non-electronic storage methods that do not involve a memory means capable of being written to or read from via signal processing.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
The innovation was using the incoming interrogation signal not just for communication, but as a power source to energize the device, solving the problem of how to power a remote, battery-less sensor.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Electronic toll collection systems like E-ZPass
Contactless payment cards
Retail inventory tracking tags
Animal identification microchips
Building access control badges
Why it matters
The bigger picture
This patent is widely considered the foundational document for RFID technology. It established the core architecture for passive tags used today in everything from inventory management and toll collection to secure building access and pet microchipping.
Filed
May 21, 1970
Granted
January 23, 1973
Market context
Who's building on this
Companies in this space
Companies like NXP Semiconductors, Impinj, and Alien Technology have built massive businesses refining the passive RFID concepts outlined here. These firms continue to advance the efficiency of energy harvesting and data storage density for tags.
Market impact
This patent enabled the entire passive RFID industry, creating a multi-billion dollar market for tracking physical goods. It shifted logistics from manual scanning to automated, wireless identification, fundamentally changing global supply chain management.
Claim 1 — Plain English
What this patent covers
This patent describes a transponder that acts as a remote data storage device. It uses an incoming signal from a base station to wake up, power its internal circuits, and either read or write data to its memory. Once the data is processed, the device sends an answerback signal back to the base station. By harvesting energy directly from the interrogation signal, the device eliminates the need for an internal battery, making it entirely self-contained.
The clever bit
The innovation was using the incoming interrogation signal not just for communication, but as a power source to energize the device, solving the problem of how to power a remote, battery-less sensor.
What it does not cover
- Does not cover active transponders that rely on internal batteries for their primary power source.
- Does not cover systems where the base station does not provide the energy for the transponder's operation.
- Does not cover non-electronic storage methods that do not involve a memory means capable of being written to or read from via signal processing.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
This patent is in the public domain
See the Freedom to Build guide — what is free to use, what is not, and how to cite this patent.
PatentBrief Score
Impact Score
Moderate
Citation count
40/40
Highly cited
Claim breadth
6/20
Moderate scope
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$60K – $192K
Midpoint $120K · expired or expiring · industry ×1.6
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Patent Claims
0 independent claims · 1 dependent
Claims are the legal boundaries of the patent. An independent claim stands alone. A dependent claim adds limitations to its parent, narrowing — but not broadening — the scope.
The original legal language
Original claims
9 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Cardullo, M., & Parks, W. (1973). How Radio Frequency Identification (RFID) Tags Were Invented (U.S. Patent No. 3,713,148). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/3713148/rfid-transponder-cardullo
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Radio Frequency Identification (RFID) Tags Were Invented cover?
A 1970 patent describing a remote tag that powers itself using incoming radio signals to read and write data, forming the foundation of modern RFID technology.
Who owns patent US 3713148?
Communications Services Corp Inc owns this patent, granted in 1973.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 3713148 cited by?
This patent has been cited by 185 later patents that build on its ideas.
What problem does this patent solve?
This patent is widely considered the foundational document for RFID technology. It established the core architecture for passive tags used today in everything from inventory management and toll collection to secure building access and pet microchipping.
What does this patent NOT cover?
Does not cover active transponders that rely on internal batteries for their primary power source.
Patent monitoring