Yeah, papers are good and fine. Tho more often than not the speculations easily goes too way optimistic.
Let's say that L-band array potentials. Especially if one make optimistic prediction on power of the TRM's. Allowances on cooling has to be taken account for. Ausairpower specify cooling was through conduction where the heat flows out of the radar through the metal ribs for dissipation. This limit the cooling capacity to about 1.15 KW/sqm, which in turn limit the average power dissipation of the array. Which can be estimated with following :
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For AESA TRM of today, typical efficiency of 35% can be assumed. More is possible depend on the class of the amplifiers (How the amplifier are biased that is). The most linear A-class is the least efficient, but also desireable for signal purity. Radar can do however other class e.g B,C which efficiency can reach 60-70%, but filtering is necessary as there would be spurious harmonics from its operations.
Now if A-class is used.. like Zhuk-AE which use A-class and cooling capacity from conduction of 1.15 KW/sqm, 12 elements and L-band say 30 cm wavelength (about 1000 MHz). Using equation above, the available cooling limits the Average power to 334 Watt for 1 array.
Regardless how much Peak power TRM can provide, the average power are limited to that amount. Any increase would require :
-Increase in cooling capacity (say, switch to liquid) with penalty in weight and volume
-Reduction of duty cycle, means low PRF waveform with long pulse which cost the radar in range and minimum range. Long pulse means the radar might not be able to detect close target determined by the pulse length. e.g 1000 microseconds (typical for L-band Radar) equals to minimum range of 1000*150 (1 us of pulse is 150m ), 150000 m or 150 km. You cannot detect target that close. This typically addressed by transmitting a second shorter "cover pulse" waveform, this imply increase in duty cycle.
-More TRM thus increase the surface area one can dissipate heat but do one have the leisure for wing leading edge ?
Not really, you can read in David Adamy's EW-101. That equation is based on an array of dipole antenna, pretty much suitable for a linear array. The basic form of this equation is this :
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The constant is of course can be adjusted based on test result, but the basic is there.
