Many different types of radar have been used in military operations over the last century. But in today’s tactical radar market, solid-state radar is the standard. However, before the invention of broadband technology, the original compact combat radars were powered by a magnetron.
While magnetron radar is virtually obsolete nowadays, it played a critical role in the development of modern radar sensors. In this blog, we’re going to compare and contrast solid-state vs. magnetron radar. But before we do that, let’s take a look at the history of military radar.
The Rise of Military Radar
While the basics of radio detection and ranging originated in the 1880s, serious interest in radar technology didn’t begin until the brink of World War II in the mid-late 1930s.
At that time, several major countries had developed long-range bombers that could carry large payloads. This advancement in strategic bombing paired with the growing possibility of war prompted militaries to find effective new ways to detect hostile aircraft approaching.
As a result, the United States, Soviet Union, Netherlands, Great Britain, Germany, France, Japan, and Italy all began experimenting with radiofrequency. By the start of World War II, most of these eight countries had operational radar equipment, the first being Great Britain’s Chain Home system.
Developed by radio expert Robert Watson-Watt, the British Chain Home was a network of 100-meter tall radar towers that each had a range of about 80 miles and provided a 15-minute warning of threats coming by land and sea. Although the system certainly had its flaws, having advance notice of German attacks gave the British a significant advantage during the 1940 Battle of Britain and is sometimes credited for the Allied Powers winning the war.
But while the Chain Home did fulfill its purpose, the major success for the U.S. and Great Britain during WWII was the invention of the magnetron radar.
Image from the book “Principles of Modern Radar” by Mark Richards
What is Magnetron Radar?
Before we answer that question, we must first explain what a cavity magnetron is.
A cavity magnetron is a vacuum tube that generates high-powered electromagnetic waves. It consists of a straight wire cathode, coaxial anode, and a series of cavity resonators (small open cavities within a metal block).
As the magnetron generates an electric field, a magnetic field must be applied longitudinally by an external magnet. Within the magnetic field, the electrons move through the cavities and create a strong microwave signal.
The cavity magnetron oscillator was developed by British physicists at the University of Birmingham. In 1940, the British introduced the concept to researchers at the Massachusetts Institute of Technology (MIT) Radiation Laboratory, where they further developed the technology to be used for military radar applications.
So, what is magnetron radar? Simply put, a magnetron radar is a microwave radar. It’s based on a cavity magnetron oscillator that transmits high-frequency energy in quick bursts, which are broadcast from small antennas. This type of radar gave the Allies a huge lead in the war, as it was much more effective than their opponents’ radar technology.
By the end of the war, practically every Allied radar was powered by a magnetron. And although magnetron radars became the standard for radar technology following the war, their pitfalls soon became apparent, such as:
- An inconsistent output signal from pulse to pulse.
- Ineffective moving-target indication (MTI).
- Inefficient at removing clutter on the radar display.
By the 1960s, developments in mono-pulse tracking radar and Doppler radar created a massive shift away from magnetron radar. While magnetrons are used in some marine radar applications, they’re almost exclusively used in low-priced microwave ovens today.
What is Solid-State Radar?
Solid-state radar, or broadband radar, is the primary type of radar for modern tactical applications. They are powered by semiconductor technology rather than a vacuum tube.
Unlike a magnetron radar that broadcasts high-powered pulses over short ranges, solid-state radars have a low radar power transmission over much longer intervals.
Instead of transmitting a single output wave, solid-state broadband radar outputs a continuous, frequency-stable signal using pulse-compression technology. They use less energy than conventional pulse radars and achieve sharper returns.
Advantages of Solid-State Radar
There are many advantages of using solid-state vs. magnetron radar. Here are eight major benefits of broadband radar technology:
1. Increased Maintainability and Reliability
Solid-state radars do not require nearly as much radar maintenance as magnetron-based ones. Cavity magnetrons are designed with parts that require annual replacement, which increases their overall cost. Solid-state radars will endure for years with minimal necessary maintenance. This leads to an increased Mean time Between Failures (MTBF) which for a solid-state radar is generally capped at 50,000 hours, while a magnetron radar is at 3,000 hours.
2. Eliminates Single Point of Failure
Solid-state radars are typically employed with an array of elements with distributed power amplifiers at each antenna element. If several amplifiers fail, the radar remains operational and with negligible performance degradation. For a radar using a magnetron, all the power required for transmission is generated solely by the magnetron. If the magnetron fails, the radar becomes inoperable and must be repaired.
3. Increase in Scan Speed
Magnetrons are typically used with gimbaled reflector antennas. Solid-state power is primarily used with AESAs. AESAs can scan radar beams on the order of nanoseconds while reflector antennas are scanned on the order of milliseconds to microseconds.
4. More Energy Efficient
Solid-state radar power transmission is very low compared to magnetron radar (a few Watts vs. Kilowatts). Instead of a single source of generated power (magnetron), the power generation is distributed across 100s to 1000s of array elements. This saves energy and decreases the cost of operation (increase in maintainability and reliability).
5. Variable Frequency
Solid-state radars are typically agile enabling operation over a large operational bandwidth (100s of MHz to several GHz). Magnetron radars, on the other hand, are typically narrow band and do not support wideband frequency operation.
6. Doppler Processing
Solid-state radars can be upgraded to include a Doppler processing unit for determining target velocity for tracking. This helps the radar determine how fast objects are moving and predict their future direction. Magnetron radars in general do not have the capability for Doppler processing since they are non-coherent. Magnetron radars can be made coherent but with added complexity/implementation.
7. No Warm-Up Time
Magnetron radars take at least 60-90 seconds to warm up before they can send out signals. Solid-state radars have an instant power feature, so no time is wasted before operation. And when it comes to keeping warfighters safe on the battlefield, time is of the essence.
8. Digital Beamforming for Multi-Function Operation
Solid-state radars can be made with digital outputs enabling digital radar beamforming. This allows the return energy to be added in such a way to adaptively create nulls to filter jamming threats. Additionally, multiple simultaneous beams can receive improving search rate speed. Magnetron radars are not used for digital beamforming radars limiting them in regards to multi-function operation.
Reliable Solid-State Radars from RADA USA
RADA USA offers the highest performing solid-state AESA radars for identifying and neutralizing all aerial threats. Our combat-proven radar systems can be used for the following operations:
Software-defined and multi-mission capable, these advanced broadband radars are essential components for keeping our American warfighters safe.