The Future of Small Radar Technology

Directing the limited resources of Fighter Command to intercept a fleet of Luftwaffe bombers en route to London or accurately engaging the Imperial Navy at 18,000 yards in the dead of night. This was our grandfather’s radar, the technology that evened the odds in World War II.

This is the combat information center aboard a World War II destroyer with two radar displays.

This is the combat information center aboard a World War II destroyer with two radar displays.

Today there is an insatiable demand for short-range sensors (i.e., small radar technology)—from autonomous vehicles to gaming consoles and consumer devices. State-of-the-art sensors that can provide full 3-D mapping of a small-target scenes include laser radar and time-of-flight (ToF) cameras. Less expensive and less accurate acoustic and infrared devices sense proximity and coarse angle of arrival. The one sensor often overlooked by the both the DIY and professional designer is radar.

However, some are beginning to apply small radar technology to solve the world’s problems. Here are specific examples:

Autonomous vehicles: In 2007, the General Motors and Carnegie Mellon University Tartan Racing team won the Defense Advanced Research Projects Agency (DARPA) Urban Challenge, where autonomous vehicles had to drive through a city in the shortest possible time period. Numerous small radar devices aided in their real-time decision making. Small radar devices will be a key enabling technology for autonomous vehicles—from self-driving automobiles to unmanned aerial drones.

Consumer products: Recently, Massachusetts Institute of Technology (MIT) researchers developed a radar sensor for gaming systems, shown to be capable of detecting gestures and other complex movements inside a room and through interior walls. Expect small radar devices to play a key role in enabling user interface on gaming consoles to smartphones.

The Internet of Things (IoT): Fybr is a technology company that uses small radar sensors to detect the presence of parked automobiles, creating the most accurate parking detection system in the world for smart cities to manage parking and traffic congestion in real time. Small radar sensors will enable the IoT by providing accurate intelligence to data aggregators.

Automotive: Small radar devices are found in mid- to high-priced automobiles in automated cruise control, blind-spot detection, and parking aids. Small radar devices will soon play a key role in automatic braking, obstacle-avoidance systems, and eventually self-driving automobiles, greatly increasing passenger safety.

Through-Wall Imaging: Advances in small radar have numerous possible military applications, including recent MIT work on through-wall imaging of human targets through solid concrete walls. Expect more military uses of small radar technology.

What is taking so long? A tremendous knowledge gap exists between writing the application and emitting, then detecting, scattered microwave fields and understanding the result. Radar was originally developed by physicists who had a deep understanding of electromagnetics and were interested in the theory of microwave propagation and scattering. They created everything from scratch, from antennas to specialized vacuum tubes.

Microwave tube development, for example, required a working knowledge of particle physics. Due to this legacy, radar textbooks are often intensely theoretical. Furthermore, microwave components were very expensive—handmade and gold-plated. Radar was primarily developed by governments and the military, which made high-dollar investments for national security.

Small radar devices such as the RFBeam Microwave K-LC1a radio transceiver cost less than $10 when purchased in quantity.

Small radar devices such as the RFBeam Microwave K-LC1a radio transceiver cost less than $10 when purchased in quantity.

It’s time we make radar a viable option for DIY projects and consumer devices by developing low-cost, easy-to-use, capable technology and bridging the knowledge gap!
Today you can buy small radar sensors for less than $10. Couple this with learning practical radar processing methods, and you can solve a critical sensing problem for your project.

Learn by doing. I created the MIT short-course “Build a Small Radar Sensor,” where students learn about radar by building a device from scratch. Those interested can take the online course for free through MIT Opencourseware or enroll in the five-day MIT Professional Education course.

Dive deeper. My soon-to-be published multimedia book, Small and Short-Range Radar Systems, explains the principles and building of numerous small radar devices and then demonstrates them so readers at all levels can create their own radar devices or learn how to use data from off-the-shelf radar sensors.

This is just the beginning. Soon small radar sensors will be everywhere.

Electromagnetic Compliance Protection (EE TIP #115)

Electromagnetic compatibility (EMC) compliance is one of the last processes before a device may be released to the public. EMC goes hand-in-hand with electromagnetic immunity (EMI), but immunity is only needed for critical devices. With EMC, it is very important to find a good EMC company to deal with. With most circuits, the weak point for EMC is any external leads. By adding a few inexpensive parts, EMC protection can be added and the EMC filtering can be adjusted by changing the values of the parts. In the figure below, the 1 µH inductors act as chokes to block any external voltage spikes above a certain frequency. The 1 nF capacitor also acts as a shock absorber to reduce any sharp voltage spikes. Effectively, this is a second-order filter and the cutoff frequency may be reduced by increasing the inductance and capacitance.

EMC ProtectionEditor’s Note: This EE Tip was written by Fergus Dixon of Sydney, Australia. Dixon, who has written two articles and an essay for Circuit Cellar, runs Electronic System Design, a website set up to promote easy to use and inexpensive development kits. Click here to read his essay “The Future of Open-Source Hardware for Medical Devices.”

PWM Controller Uses BJTs to Reduce Costs

Dialog iW1679 Digital PWM Controller

Dialog iW1679 Digital PWM Controller

The iW1679 digital PWM controller drives 10-W power bipolar junction transistor (BJT) switches to reduce  costs in 5-V/2-A smartphone adapters and chargers. The controller enables designers to replace field-effect transistors (FETs) with lower-cost BJTs to provide lower standby power and higher light-load and active average efficiency in consumer electronic products.

The iW1679 uses Dialog’s adaptive multimode PWM/PFM control to dynamically change the BJT switching frequency. This helps the system improve light-load efficiency, power consumption, and electromagnetic interference (EMI). The iW1679 provides high, 83% active average efficiency; maintains high efficiency at loads as light as 10%. It achieves less than 30-mW no-load standby power with fast standby recovery time. The controller meets stringent global energy efficiency standards, including: US Department of Energy, European Certificate of Conformity (CoC) version 5, and Energy Star External Power Supplies (EPS) 2.0.

The iW1679 offers a user-configurable, four-level cable drop compensation option. It comes in a standard, low-cost, eight-lead SOIC package and provides protection from fault conditions including output short-circuit, output overvoltage, output overcurrent, and overtemperature.

The iW1679 costs $0.29 each in 1,000-unit quantities.

Dialog Semiconductor
www.iwatt.com