Silicon SPDT Reflective Switches

Researchers at Rutgers University–New Brunswick have found that ordinary Wi-Fi can be used to easily detect weapons, bombs, and explosive chemicals in bags at public venues.

Their study – "Towards In-baggage Suspicious Object Detection Using Commodity WiFi" – demonstrates a low-cost Wi-Fi-based technology for security screening at public venues like stadiums, theme parks and schools. The suspicious object detection system, say the researchers, is easy to set up, reduces security screening costs, and avoids invading privacy such as occurs when screeners open and inspect bags, backpacks, and luggage.

"This could have a great impact in protecting the public from dangerous objects," says Yingying (Jennifer) Chen, co-author of the study and a professor in the Department of Electrical and Computer Engineering in Rutgers–New Brunswick’s School of Engineering. "There's a growing need for that now."

Ubiquitous Wi-Fi wireless signals in most public places, say the researchers, can penetrate bags to get the dimensions of dangerous metal objects and identify them, including weapons, aluminum cans, laptops and batteries for bombs. Wi-Fi can also be used to estimate the volume of liquids such as water, acid, alcohol and other chemicals for explosives, according to the study.

The low-cost object detection system system requires a Wi-Fi device with two to three antennas and can be integrated into existing Wi-Fi networks. The system analyzes what happens when wireless signals penetrate and bounce off objects and materials.

The system uses the fine-grained channel state information (CSI) from off-the-shelf Wi-Fi. This information describes how a signal propagates from the transmitter to the receiver and represents the combined effect of such effects as scattering, fading, and power decay with distance.

The system first detects the existence of suspicious objects and identifies the dangerous material type based on the reconstructed CSI complex value (including both amplitude and phase information). It then determines the risk level of the object by examining the object's dimension - that is, a liquid volume or metal object's shape - based on the reconstructed CSI complex of the signals reflected by the object.

Experiments with 15 types of objects and six types of bags demonstrated detection accuracy rates of 99% for dangerous objects, 98% for metal and 95% for liquid, say the researchers. For typical backpacks, the accuracy rate exceeds 95% and drops to about 90% when objects inside bags are wrapped.

Looking ahead, say the researchers, next steps include trying to boost accuracy in identifying objects by imaging their shapes and estimating liquid volumes.

Analog Devices’ switches for radios, scanners, and test and measurement equipment

ADI’s ADRF5024/ADRF5025 are reflective single-pole double-throw (SPDT) switches. The ADRF5024 operates from 100 MHz to 44 GHz with better than 1.7 dB of insertion loss and 35 dB of isolation whereas the ADRF5025 operates from 9 kHz to 44 GHz with better than 1.6 dB of insertion loss and 35 dB of isolation. Both switches have a radio frequency (RF) input power handling capability of 27 dBm for both the through path and hot switching.

The ADRF5024/ADRF5025 draws a low current of 14 μA on the positive supply of +3.3 V and 120 μA on a negative supply of -3.3 V. The device employs complementary metal-oxide semiconductor (CMOS)-/low voltage transistor to transistor logic (LVTTL)-compatible controls.

Both switches’ RF ports are designed to match a characteristic impedance of 50 Ω. For ultrawideband products, impedance matching on the RF transmission lines can further optimize high frequency insertion loss and return loss characteristics. These switches come in a 2.25 mm × 2.25 mm, 12-pin land grid array (LGA) package and can operate from -40°C to +105°C. The ADRF5024/ADRF5025 are ideal for radios, scanners, and test and measurement equipment.

Features
Frequency range: 9 kHz to 44 GHz Frequency range: 100 MHz to 44 GHz Reflective design Low insertion loss with impedance match Low insertion loss without impedance match 0.9 dB typical to 18 GHz 1.7 dB typical to 40 GHz 2.1 dB typical to 44 GHz		High input linearity P1dB: 27.5 dBm typical IP3: 50 dBm typical High RF input power handling Through path: 27 dBm Hot switching: 27 dBm No low frequency spurious RF settling time (50% VCTRL to 0.1 dB of final RF output): 17 ns
Applications
Cellular infrastructure: 5G mmWave Industrial scanners Test and instrumentation		Military radios, radars, electronic counter measures (ECMs) Microwave radios and very small aperture terminals (VSATs)

ADRF5024 and ADRF5025 Eval Boards

	Image	Manufacturer Part Number	Description	Available Quantity	View Details
		ADRF5024-EVALZ	EVAL BOARD	14 - Factory Stock
		ADRF5025-EVALZ	EVAL BOARD	3 - Immediate

ADRF5024 and ADRF5025 Switches

	Image	Manufacturer Part Number	Description	Available Quantity	View Details
		ADRF5025BCCZN	40 GHZ, LOW LOSS, REFLECTIVE, LO	485 - Immediate 76 - Factory Stock
		ADRF5025BCCZN-R7	40 GHZ, LOW LOSS, REFLECTIVE, LO	6500 - Factory Stock
		ADRF5024BCCZN	40GHZ, LOW LOSS, REFLECTIVE, FAS	464 - Immediate 230 - Factory Stock
		ADRF5024BCCZN-R7	40GHZ, LOW LOSS, REFLECTIVE, FAS	3500 - Factory Stock

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Published: 2018-08-08