Stealth II

by
Robert Waldmann
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I think that with “Stealth” I indulged my inclination to try to figure things out more than I should have.The practical point is my claim that stealth technology is obsolete. I think this is well known and yet not allowed to effect the US Federal Budget.

I cite the Wikipedia

“Low-frequency radar[edit]

Shaping offers far fewer stealth advantages against low-frequency radar. If the radar wavelength is roughly twice the size of the target, a half-wave resonance effect can still generate a significant return. However, low-frequency radar is limited by lack of available frequencies (many are heavily used by other systems), by lack of accuracy of the diffraction-limited systems given their long wavelengths, and by the radar’s size, making it difficult to transport. A long-wave radar may detect a target and roughly locate it, but not provide enough information to identify it, target it with weapons, or even to guide a fighter to it.^[38]

Multiple emitters[edit]

Much of the stealth comes in directions different than a direct return. Thus, detection can be better achieved if emitters are separate from receivers. One emitter separate from one receiver is termed bistatic radar; one or more emitters separate from more than one receiver is termed multistatic radar. Proposals exist to use reflections from emitters such as civilian radio transmitters, including cellular telephone radio towers.^[39]

Moore’s law[edit]

By Moore’s law the processing power behind radar systems is rising over time. This will eventually erode the ability of physical stealth to hide vehicles.^[40][41]“

I claim that this is what I wrote (I note I was writing before reading as I usually do). I would still argue that the problem with determining location with long wavelength radio waves is easy to solve in 3 different ways

1. I think one gets a fairly accurate indication of distance using the time from pulse to receipt of the echo. Only a huge apparatus can get an accurate assessment of the direction to the target. This is a statement about the size of the radar system not a single component. WIth multiple receivers one gets multiple estimates of distance and 3 distances imply a location. The argument is that to find the location of a stealthy target one has to manage to get separate devices to work together in a network. This is a solved problem,
2. The beam from an other than huge antenna is broad. However, it is not uniform. A phased array radar can move the beam arbitrarily far from pulse to pulse (that is roughly once a millisecond) by changing the amplitudes and phases of transmission from different subcomponents. The problem of where is the target if the echo gets stronger if we move the center of the beam a bit North, weaker if we move it a bit East and stronger if we move it a bit up is easily solved. This is an information processing problem which is not trivial.
3. Interferometry. It is possible to measure distance mod wavelength by interference of return signal and a signal of the same frequency. For meter long waves, this would mean the target is N meters plus a known fraction. WIth pulses of a meter, 99 CM and 101 CM this would give location plus or minus an even multiple of 999 meters. If the target is moving on the order of a meter a second, use 99cm meter 101cm meter 99 cm and average the phase of the 2nd and 4th pulses and of the first and fifth pulses. The problem is acceleration and if it must be less than 10 Gs then the gap between where the target is and where it would be assuming zero acceleration is about a millimeter (98 * (4^2)/2)/(1000^2) meters. If there is a pilot in the target, it can’t accelerate over 9 Gs. Againe multiple receivers and 3 distances equal a location.

I think the problem is solved and has been solved for a long time.

Another Wikipedia article

“Sensors made to reduce the impact of current low observable technologies exist or have been proposed such as IRST (infrared search and track) systems to detect even reduced heat emissions,^[8] long wavelength radars to counter stealth shaping and RAM focused on shorter wavelength radar,^[9] or radar setups with multiple emitters to counter stealth shaping.^[10] However these do so with disadvantages compared to traditional radar against non-stealthy aircraft.”

(notice I guessed 3 out of 4 and I’m a macroeconomist). The US is spending hundreds of billions in exchange for unspecified “disadvantages” for adversaries. I think that adversaries who can manage a network and communicate with signals we can’t jam are not significantly disadvantaged (but as always I am ignorant).

I note that the US Military has proposed a $ 200 billion dollar program (before overruns) to develop and procure the B-21 a new stealthy strategic bomber which together might (but probably won’t) be able to do the job of 5,000 Tomahawks costing $ 10 billion (more likely Congress will be displeased by cost over runs and we end up with around 20 B-21s to supplement the 20 B2s built at a total cost of over $40,000,000,000.