Telecoms, Datacoms, Wireless, IoT


How well does RFID energy pass through objects?

15 June 2005 Telecoms, Datacoms, Wireless, IoT

RFID (radio frequency identification) has the ability to identify tags that are not optically visible from the reader. Passive tags extract their operating energy from the energising field radiated by the reader, which available energy decreases as it travels away from the reader, placing a limit on the operating range that can be achieved with a specified radiated power and transponder sensitivity.

What happens when the energy has to pass through a ream of paper, or a plank of mahogany wood, before getting to the transponder. The short answer is that only 37% of the energy is going to pass through the paper, or 53% through the wood. And this does not matter whether the object is only a couple of centimetres thick, or more than 10 cm thick.

The reason for this loss of energy transmission relates to a property of the material called 'dielectric constant'. Wherever the energy wave encounters a change in dielectric constant (eg, air-to-paper, paper-to-air), part of the energy is reflected at the transition layer and never reaches the tags. Engineers who have experience in high resolution short range radar, such as ground penetrating radars, use this principle to detect objects buried in the ground.

The reflected energy caused by the transition of dielectric constant, results in a benefit to users of UHF RFID in that the radio signals also reflect off walls and floors, allowing tags that might normally be screened via a direct path approach, to get their energy from redirected reflected energy.

If you would like to know more, a detailed presentation, together with tables showing the reflection and transmission percentages for a variety of materials can be seen at www.trolleyscan.com/refltran.html





Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

RF fixed chip attenuators
29 January 2020, RF Design , Telecoms, Datacoms, Wireless, IoT
The TT5 Series from Smiths Interconnect are Q-band chip attenuators that operate from DC to 18 GHz. The broadband attenuators are available in attenuation values from 0 to 20 dB in 0,5 dB increments and ...

Read more...
RF variable attenuator
29 January 2020, RF Design , Telecoms, Datacoms, Wireless, IoT
The 4209-30-63-1 from API Technologies - Weinschel is a solid-state programmable attenuator that operates from 0,1 to 30 GHz. It has an attenuation range from 0 to 63 dB with a step size of 0,5 dB and ...

Read more...
Thingstream extends LoRaWAN support
29 January 2020, Altron Arrow , Telecoms, Datacoms, Wireless, IoT
It is now possible to add LoRaWAN gateways and LoRaWAN devices to Thingstream, giving developers quick, easy on-boarding, and the full power of Thingstream’s MQTT broker, and Data Flow Manager. This new ...

Read more...
Wi-Fi 6 front-end module
29 January 2020, Hi-Q Electronics , Telecoms, Datacoms, Wireless, IoT
Skyworks has introduced the SKY85772-11, a new addition to its family of front-end modules (FEMs) that are designed for growing retail, carrier and enterprise Wi-Fi 6 applications. The 5 GHz FEM offers ...

Read more...
RF power amplifier for 18 - 26 GHz
29 January 2020, RFiber Solutions , Telecoms, Datacoms, Wireless, IoT
The MAAP-118260 is a packaged linear power amplifier that operates over the frequency range 17,7 – 26,5 GHz. The device, manufactured by MACOM, provides 28,5 dB of gain and 37,0 dBm output third order ...

Read more...
Wideband GaN power amplifier
29 January 2020, RF Design , Telecoms, Datacoms, Wireless, IoT
Qorvo introduced what it claims is the world’s highest-performance wideband power amplifier (PA). Designed for electronic warfare, radar and test instrumentation applications, the TGA2962 boasts 10 W ...

Read more...
GaN is breaking barriers for RF power amplifiers
29 January 2020, Altron Arrow , Telecoms, Datacoms, Wireless, IoT
The increasing demand for higher data rates in telecommunications and higher resolution in industrial systems is pushing the frequency of operation higher for the electronics that support them. Many of ...

Read more...
V2X: The future of vehicle communications
29 January 2020, Avnet South Africa , Editor's Choice, Telecoms, Datacoms, Wireless, IoT
A recent report by Juniper Research forecasts that more than 62 million vehicles will be capable of vehicle-to-vehicle communication by 2023; up from just over 1,1 million in 2019.

Read more...
PCIe 2.0 packet switches
29 January 2020, Altron Arrow , Telecoms, Datacoms, Wireless, IoT
Diodes Incorporated announced the PI7C9X2G304EVQ and PI7C9X2G404EVQ PCIe 2.0 packet switches, offering 3-ports/4-lanes and 4-ports/4-lanes, respectively. The packet switches are automotive-compliant for ...

Read more...
High-performance IoT SoCs with dual processors
29 January 2020, RF Design , Telecoms, Datacoms, Wireless, IoT, Editor's Choice
Nordic Semiconductor’s new nRF5340 high-end multiprotocol system-on-chip (SoC) is the first member of its next generation of nRF5 Series SoCs. The nRF5340 builds on Nordic’s proven and globally adopted ...

Read more...