New invisibility cloak makes objects undetectable to radar

Researchers claim that a new invisibility cloak can make certain objects undetectable even to radar.

George Eleftheriades, an electrical and computer engineering professor at the University of Toronto, along with his graduate student, Michael Selvanayagam, said that they can hide a metal cylinder from radar detection, or even make a metal cylinder appear bigger, smaller or look like plastic.

"We came up with a different way of cloaking," said Eleftheriades "We can make things invisible or we can camouflage them. Let me explain."

Eleftheriades says that to understand how cloaking works someone should first know how a radar works. The professor explains that when light hits any object it bounces back and makes the object visible to the eyes. Similarly, when radio waves hit an object it bounces back to the radar detector, which in turn reveals the object. The concept is very similar to noise-canceling feature in headphones.

Do Russian Radar Developments Challenge Stealth? – Commentary by Bill Sweetman

Even when stealth technology was deadly secret and the F-117A did not officially exist, there was counter-stealth radar.

Textbooks told us radar cross-section (RCS) was frequency dependent, and tended to become increasingly so as the target shape grew more complicated. If the radar wavelength is of the same magnitude as prominent features of the target, the signal is scattered by a resonant mechanism that is unimpressed by cunning shaping or materials magic. In the 1980s, many older Russian systems operated in the VHF band, with wavelengths in the 1-2-meter range, which is about the same as the chord of a fighter’s tail surfaces and wingtips.

But, as I wrote in 1987:

“The price of increasing wavelength … is that the antenna has to grow in proportion to the wavelength in order to maintain a narrow beam and adequate resolution. The ‘mobile’ Soviet VHF radars are cumbersome, and early-warning radars such as Tall King (P-14) are large fixed structures and provide coverage of only one sector. Despite the size of their antennae, they are not accurate enough to manage a complete engagement.”

Lecture “Stealth Technology”

Stealth Technology [Naeem Rezghi] from Naeem Rezghi