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By AARON SKETCHLEY (aaronsketch@HOTdelete_thisMAIL.com)

Ver 1.3 2019.05.25

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Official Setting information is in darkgreen. Extended Universe information is in steelblue.

Avionics Devices: Radar Systems

Table Of Contents
Radar Basics Pulse Doppler Radar Active Electronically Scanned Array (AESA) Ladar	AWG-20 Radar APG-995 Radar APG-997 Radar APHS-94 Radar LAPR-34 Ladar

Radar Basics

A radar system has a transmitter that emits radio signals in predetermined directions. Radar receivers are usually, but not always, in the same location as the transmitter. Although the reflected radar signals captured by the receiving antenna are usually very weak, these signals are strengthened by electronic amplifiers and other sophisticated methods of signal processing in order to recover useful radar signals.

The weak absorption of radio waves by the medium through which it passes is what enables radar sets to detect objects at relatively-long ranges, ranges at which other electromagnetic wavelengths, such as visible light, infrared light, and ultraviolet light, are too strongly attenuated. Such things as fog, clouds, rain, falling snow, and sleet that block visible light are usually transparent to radio waves. Certain, specific radio frequencies that are absorbed or scattered by water vapor, raindrops, or atmospheric gases (especially oxygen) are avoided in designing radars except when detection of these is intended.

Finally, radar relies on its own transmissions, rather than light from the Sun or the Moon, or from electromagnetic waves emitted by the objects themselves, such as infrared wavelengths (heat). This process of directing artificial radio waves towards objects is called illumination, regardless of the fact that radio waves are completely invisible to the human eye or cameras.

• Usually fighter aircraft use only the X band (8-12 GHz). List of Frequency Bands used in radar.

• signal direction
• signal strength
• signal's source's direction of travel and velocity only.

Using radar WILL alert others to your EXACT location if they are also using radar. Radar is only useful for line-of-sight searches (if you are behind a hill, in trees, among buildings, etc. radar cannot spot you; though your radio and radar broadcasts could still be intercepted.)

If support (AWACS, ELINT Seeker, Capital Ship, Funny Chinese, etc.) is available, it is recommended that players use it for radar targeting. Or players could have 1 VF flying with the radar on (and dodging incoming fire) with one or two escorts to defend it. The radar-using VF then broadcasts tactical data to the other VFs in the squadron.

Pulse Doppler Radar

Pulse-Doppler radar is crucial for military applications called look-down/shoot-down, which allows small fast-moving objects to be detected near terrain and weather. The purpose is to detect targets while eliminating hostile environmental influences, such as reflections from weather, the surface of the earth and biological objects like birds, and electronic interference, which hide reflected signals from aircraft but which move much slower than aircraft. A secondary purpose is to to reduce transmit power while achieving acceptable performance for improved safety and stealthy radar.

Pulse-Doppler radar for aircraft detection has two modes: Scan & Track. Scan mode involves frequency filtering, amplitude thresholding, and ambiguity resolution. Once a reflection has been detected and resolved, the pulse-Doppler radar transitions to tracking mode. Track mode works like a phase-locked loop, where Doppler velocity is compared with the range movement on successive scans. Lock indicates the difference between the two measurements is below a threshold, which can only occur with an object that satisfies Newtonian mechanics. Other types of electronic signals cannot produce a lock.

Active Electronically Scanned Array (AESA)

AESAs aim their "beam" by broadcasting radio energy that interfere constructively at certain angles in front of the antenna. They improve on the older passive electronically scanned radars by spreading their broadcasts out across a band of frequencies, which makes it very difficult to detect over background noise. AESAs allow ships and aircraft to broadcast powerful radar signals while still remaining stealthy.

AESA are able to do this because each module broadcasts its own independent signal. This allows the AESA to produce numerous "sub-beams" and actively "paint" a much larger number of targets. Additionally, the solid-state transmitters are able to broadcast effectively at a much wider range of frequencies, giving AESAs the ability to change their operating frequency with every pulse sent out. AESAs can also produce beams that consist of many different frequencies at once, using post-processing of the combined signal from a number of TRMs to re-create a display as if there was a single powerful beam being sent. Advantages are:

• Low Probability of Intercept: since the AESA can change its frequency with every pulse, and generally does so using a pseudo-random sequence. Traditional RWRs are essentially useless against AESA radars.
• High jamming resistance: traditionally, jammers have operated by determining the operating frequency of the radar and then broadcasting a signal on it to confuse the receiver as to which is the "real" pulse and which is the jammer's. This technique works as long as the radar system cannot easily change its operating frequency. Since an AESA changes its operating frequency with every pulse, and spreads the frequencies across a wide band even in a single pulse, jammers are much less effective. Although it is possible to send out broadband white noise against all the possible frequencies, this means the amount of energy being sent at any one frequency is much lower, reducing its effectiveness. In fact, AESAs can then be switched to a receive-only mode, and use these powerful jamming signals instead to track its source, something that required a separate receiver in older platforms.
• Generate Far More Data: than traditional radar systems, which can only receive data periodically, as they can broadcast continually while still have a very low chance of being detected, they are so much more useful in receiving signals from targets. Which greatly improves overall system effectiveness.
• High reliability: since each module operates independently of the others, single failures have little effect on the operation of the system as a whole.
• Improved Stealthiness: replacing a mechanically scanned array with a fixed AESA mount helps reduce an aircraft's overall radar cross-section (RCS). But some designs forgo this advantage in order to add the limits of mechanically scanning to the limits of electronic scanning and provide a larger angle of coverage.
• Other advantages: since each element is a powerful radio receiver, active arrays have many roles besides traditional radar. One use is to dedicate several of the elements to reception of common radar signals, eliminating the need for a separate radar warning receiver. The same basic concept can be used to provide traditional radio support, and with some elements also broadcasting, form a very high bandwidth data link.

Ladar

space and fog/cloud free night sky only.

AWG-20 Radar

• RANGE: 280 km lock-on fighter sized objects, 370 km search range.
• HEIGHT: 24,385 m to small moving targets near or on the ground not obscured by foliage.
• FREQUENCY: 8-12 GHz
• SEARCH CONE: 120° x 120° (forward hemisphere)
  • TWS (Track-While-Scan) mode: track 24 targets, engage up to 6 at the same time.
  • ACM (Air Combat Maneuvers) mode: 18 targets.
  • AGM (Air-to-Ground Mode): track 10 targets.
• PROS: greater focal detection off center axis, lower cost, ease of maintainability
• CONS: reduced stealthiness, comparitively easily jammed and lower reliability (1 component breaks, the radar becomes unusable).

APG-995 Phased Array Radar

The APG-995 features an entirely solid-state antenna construction, which improves reliability and lowers the cost compared to a traditional radar system. The APG-995 enables aircrews to simultaneously guide several missiles to several targets widely spaced in azimuth, elevation or range. It has a higher processor throughput, greater memory capacity, bandwidth, frequency agility, higher analogue/digital sampling rates, improved reliability and ease maintenance.

• RANGE: 375 km lock-on fighter sized objects.
• HEIGHT: 24,385 m to small moving targets near or on the ground not obscured by foliage.
• FREQUENCY: 8-12 GHz
• SEARCH CONE: 120° x 120° (forward hemisphere)
  • ACM (Air Combat Maneuvers) mode: track 30 targets during high G manuvers.
  • AGM (Air-to-Ground Mode): track 10 targets.

APG-997 Phased Array Radar

• RANGE: 375 km lock-on fighter sized objects.
• HEIGHT: 24,750 m to small moving targets near or on the ground not obscured by foliage.
• FREQUENCY: 8-12 GHz
• SEARCH CONE: 120° x 120° (forward hemisphere) [if the array is added to a mechanically scanned unit, than the search cone increases to 180° x 180°, but stealthiness is reduced.]
  • ACM (Air Combat Maneuvers) mode: track 30 targets during high G manuvers
  • AGM (Air-to-Ground Mode): track 12 targets.

APHS-94 Phased Array Radar

• RANGE: 550 km lock-on fighter sized objects.
• HEIGHT: 25,000 m to small moving targets near or on the ground not obscured by foliage.
• FREQUENCY: under investigation
• SEARCH CONE: 360° arc
  • ACM (Air Combat Maneuvers) mode: track 45 targets during high G manuvers
  • AGM (Air-to-Ground Mode): track 18 targets.

LAPR-34 Radar

• RANGE: can image a 10 cm object at 10,000 m.

REFERENCES

Palladium Books Game Engine and MDC Rules Macross Chronicle This is Animation Special: Macross Plus

Great Mechanics and Great Mechanics.DX Variable Fighter Master File: VF-1, VF-1 Space Wings, VF-19 & VF-25 Wikipedia