Cassegrain antenna report

Stablized Lamp Light Guide The compensating lens 3 was an elegant feature, designed to cancel out the refractive effect of the thick quartz pressure window. Focusing at the hyperfocal distance yielded a depth of field from 0.

Cassegrain antenna report

Russian specifications almost uniformly assume a 4: All later antenna apertures are 0. Public specs claim 34 to 36 dB gain for most variants, parametric analysis suggests up to 39 dB gain. An example of where the latter form [dBW] gets into difficulties is in different specifications of antenna gain, including or excluding feed losses, or situations where an incremental design change to a feed or antenna removes several dB of loss previously listed.

Different clients are often supplied with different TWT ratings on a given radar type. Detection range performance figures for many older radar variants are not specified in terms of a target Radar Cross Section [RCS] and are thus difficult to objectively assess.

What is clear from available data published by Russian manufacturers over the last fifteen years is that the Flanker has seen a roughly fivefold growth in the power aperture product performance of available radar designs.

In practical terms, this amounts to a gross increase in detection range performance of around 50 percent since the N was first deployed, and a gross increase in jammer burnthrough performance of around percent.

Assessing late model Flanker radar range and burnthrough performance by using the baseline N and its variants as a benchmark is therefore a complete folly. It is akin to using s US fighter radars as a benchmark for assessing the capability of current US production fighter radars.

From a strategy and force structure planning perspective, the N and its variants are now of marginal relevance, as the more capable and newer radars will progressively displace them in the marketplace and thus in deployed force structures.

Tactical Implications of High Power Aperture Product Fighter Radars The conventional wisdom in BVR combat is that the player with the longer ranging radar wins the game as the radar provides the opportunity to detect the opponent earlier, initiate tracking and identification, and launch a missile shot first.

This is however predicated on several assumptions: The player with the longer ranging radar has a longer ranging missile to facilitate a first shot. The player with the shorter ranging radar does not have the capability to effectively jam the radar. Missile kinematic performance is thus critical, and a prerequisite if one seeks to gain an advantage by deploying a longer ranging radar than an opponent has.

Missile range will be determined in part by the design of the missile, specifically how much energy is stored in its rocket or ramjet propellant, and how good the midcourse autopilot software is in converting that energy into range, but the kinematics of the launch aircraft also matter immensely.

The Russian drive to improve supersonic persistence in the Flanker via supercruise class engines is clearly in a large part driven by this reality. In the bluntest of terms, throwing a spear from the top of a hill is always easier than throwing one uphill.

Electronic warfare between opponents remains a key consideration in long range missile combat. While high power aperture radars provide good burnthrough performance, at extreme ranges well in excess of 50 nautical miles burnthrough is unlikely to be a practical proposition.

This is because the power ratings of conventional defensive jamming systems will be sized to defeat surface based engagement radars with power aperture performance well in excess of any fighter radar.

Abbreviations List by

What does become a proposition for both sides is jamming of the missile midcourse datalink uplink channel to deny midcourse flight position updates after a missile launch. Historically the jamming of missile uplinks has been considered difficult and demanding of high power levels.

This is because missile datalink antennas point in the direction of the launching aircraft, which means that what little jamming power can couple into the antenna must be carried by surface travelling waves along the missile airframe. However, both sides also have the option of coating their missiles with X-band lossy materials, which will diminish the coupling effect.

If was specifically built to hunt cruise missiles, and is claimed to be able to detect a 0. It remains the benchmark in this technology, a large element AESA design. This has created an effect not unlike euphoria in some parts of the US defence industry, and a worldwide drive by global semiconductor houses to occupy the market.

Historically AESA performance was limited by the power output per module at X-band, typically of the order of 2 to 5 Watts per module. The GaN transistor technology appears at this stage to be capable of delivering ten times the power per module, which changes the problem AESA designers face from barely getting viable power output, to not having enough cooling and electrical power capacity to cope with the transistor technology available.

The long term implications of the Gallium Nitride breakthrough in X-band microwave transistor technology are most interesting. If AESA designers are not significantly limited by basic technology in the microwave power they can extract from each AESA module, then radar power aperture performance will grow until it hits the limits of the power generation and especially cooling capacity of an airframe.

With an aperture area of about 0. The utility of this range increase may be irrelevant considering conventional targets, but where it matters is in providing the ability to detect stealthy targets at very good ranges. The following chart depicts the impact of a notional very high power aperture radar on detection ranges for stealthy targets.

What is clear is that X-band fighter radars with peak power ratings well above 20 kiloWatts have the potential to render all but top end stealth technology ineffective.

While engineering such radars would present serious challenges, some arguably extremely difficult to resolve with a sub one metre aperture diameter, and possibly forcing very low operating duty cycles, it is abundantly clear that the trend will be to strive for the highest power aperture product achievable, as the incentives are very powerful.

In this game the primary constraints then become the cooling of the array and dumping of waste heat out of the aircraft. Larger aircraft do much better with these constraints, compared to smaller aircraft.

The defining characteristics for best survivability will be the size to effectively power and cool the highest power aperture product radar which can be fitted, and the best X-band all aspect stealth performance. The potential of X-band fighter radars with power ratings in excess of 20 kiloWatts to be used as Directed Energy Weapons DEW is an issue in its own right [ 2 ].These studies include, for example,dual frequency Cassegrain antennas, Flat plate antennas, Phasesteered AEW antennas, and 3D Radar antennas.

Dr. Josefssonhas taken an active role in the AIMT project (Antenna IntegratedMicrowave Technology) sponsored by FMV, the Swedish DefenseMaterial alphabetnyc.coms: 1. The idea of using parabolic reflectors for radio antennas was taken from optics, where the power of a parabolic mirror to focus light into a beam has been known since classical designs of some specific types of parabolic antenna, such as the Cassegrain and Gregorian, come from similarly named analogous types of reflecting .

Cassegrain antenna report


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