HX-fighters and their AESA radars

Even though today president Trump said that Finland had already made the decision to buy F/A18 E or if models we are still very much in the process of choosing the right fit Fighter for Finland. this piece of news was revoked right of the day occasion in Washington but it has still gained some line in Internet and news. So good people at Boeing can not brake out the fizzydrink just yet.

Rafale’s radar.

I had a misconception about the modern fighter radar technology. The radar will remain the primary censor of future generation of Fighters because the technology has developed greatly in last decades. IRST Center will also be important cause but still the fighters will count on radars to guide their missiles two Targets. this Renaissance has come about because of the AESA radars. In which the beam is not formed mechanically but rather computer controlled array of transmitter receiver modules. Basically the thing is that if the transmitter/ receiver models are spaced with carefully calculated distances and we can control the exact times in which they will transmit it is possible to guide the waves mathematically. Basically if the difference in wave form is about 60 degrees, or Pi/3 for mathematicians, the waves will start to dampen each other. Similarity they can be made to boost each other. So it is really mathematics and the power of a computers that have made the current Beasts of a fighter Radars possible.

This piece is going to be very much about the radar technology and the size of an airplane affecting the electronic environment and their reflections caused by the airplane in flight. and size really matter in this. the bigger the aeroplane more radio energy it will reflect back, and also bigger the airplane bigger radar can be fitted into the nose. Thus the size of the airframe transfers into the sending power on the radar set. And because of the inverse Square law effects immensely the probability of the radar to pick up the enemy fighters in the space. So having a bigger plane is not that much of a handicap that you might think. And smaller plane does not necessarily suffer too much because of the limited space the radar disc can have in it’s nose.

FA-18 Rhino has about 1100 transmitter/reciever elements in her APG-79 radar. Rafale’s radar is said to have 960 elements, the SAAB JAS Gripens’ Raven radar has “about 1,000” elements. Eurofighters new Captor E AESA radar is quoted to have between 1000-2000 TR elements. This would mean that it will go into the “direct energy weapon” category as its max output would climb well over 20 kW. Or something in order of 25 microwave ovens. Dassault Rafale is also quoted to have “about 1000” elements in her future AESA RBE-2 radar. So in HX program context mean that Boeing’s F/A-18 E Rhino may hold an edge over the Gripen and Rafale of about 20% in peak output, and lose about 10% to JSF or F-35 fighter. And maybe be some tens of procents weaker than Typhoon’s Captor E radar.

But this might not be too much of a hindrance for smaller nosed fighters, as larger array will by necessity have a larger radar cross-section (RCS) to hostile electromagnetic radiation than smaller one. so this is again a trade-off between capabilities. And this is why I would not write off the French all the Swedish fighter as of now.

Size of a transmitter/receive element corresponds highly with the intended wavelength of the radar. And as usually the fighter Radars operate in so-called X-band (in 8 to 12 gigahertz) the size of element is 64,5 mm x 13,5mm x 4,5mm. The key Dimension is 13.5 millimeters. which is about how the wavelength in 11 gigahertz. Power output of a single element is “about 50 wats”. So 1000*50w= 50 kW

So the output of a radar is highly dependent on the number of transmitter receiver modules it has in her radar. The radar cross-section is measured as a size of a ball of Steel that will reflect the electromagnetic energy back. bigger the sphere, more energy will be reflected back to the sending radar. Here another Factor comes into play so called inverse Square law. This tells us how great is the intensity of the radiation at the measured target. now as the radiation is reflected back the inverse Square law takes effect again, and then it is most important how good is the gain of the radar. the better the gain farther away the measured target can be picked up.

So for practical purposes you want to have as powerful radar as you can with as good as gain as you can have in order to pick up the targets from the Aerospace. stealth characteristics at the target will of will of course hurt the radars capability of finding the target. But as the airplane is usually at the most elphick head on other Radars measuring from different angles we’ll have a better chance of finding it. and with more than data links it really makes very little difference which airplane finds Target because everybody will see it.

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About epamuodikkaitaajatuksia

Reilu nelikymppinen jannu, joka on huolissaan siitä miten maanpuolustus ja turvallisuus makaa Lapissa, Suomessa ja Euroopassa. Harrastuksina Amerikkalainen jalkapallo ja SRA ammunta. A guy about 45, who has a "thang" for military current issues, defense and shooting. Not to forget American football.
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