Te paso algo que leí en un foro hace bastante ... Es de 2004 ...
Está en inglés y traductor mediante te pueda dar una idea.
Lamento no recordar el autor, creo que lo acercó por el forista blue82
Sut puede que nos de una mano.
I want to add some comments to your interesting and helpful message about
the current capabilities of the several European AAW frigate projects,
specially taking into account their sensor suites. It's very common on
Usenet and other boards to read how such and such new-generation phased
array is superior to AN/SPY-1x, "because it's active", even if some times
the reasons are obscure or directly unknown to some of the readers of such
boards. In my opinion, I don't really believe that using GaAs (Gallium
Arsenide) modules or MMIC (Monolithic Microwave Integrated Circuits) on
GaAs substrates to build a new generation active array _instantly_ makes a
better solution than the very mature passive electronically scanned fixed
phased array of AN/SPY-1x. "Newer" is not always equivalent to "better".
Let's see what are the supposed advantages of an active array with respect
to the conventional passive one on the F-100s:
a) Adaptive beamforming to counter heavy electronic jamming. This was
shown in the Sierra-band MESAR (Multifunction Electronically Scanned
Adaptive Radar) prototype, from which TRISAR/SAMPSON and other
Siemens-Plessey radars evolved. Through a complex schema of sidelobe
blanking beams and multiple subarray receivers a number of jammers can be
cancelled (15 per array with 16 receivers). Great, but ECCM is not
_exclusive_ to active array technology, and is well known that starting
from the first SPY-1B prototype the antenna design emphasized lower
sidelobes and improves dramatically jamming resistance against
self-screening and standoff jammers/repeaters, together with ECM analysis
and burn-through processing (and SPY-1x uses very brute-force burn-through
capability). So, in ECCM terms, an active array is doing what a passive
array does, with a different technology. But before we ponder too much on
this question, we have to ask ourselves _who_ exactly is going to have the
technical know-how and the tactical ability to get close enough to jam an
AEGIS system out of service and survive the experience, because such
hypothetical all-powerful threat will also jam an active array or any
other radar out of the water too.
b) Progressive degradation of system functionality instead of total
failure. This is the single _most_ important characteristic of an active
array. Since the array is composed by a large number of elementary
radiators (almost 85-90% are T/R modules, the rest being simple phase
shifters like in passive arrays), a number of them can fail or be
battle-damaged, but the system could still function. On the other hand,
the AN/SPY-1A/B have only two very powerful radiators, and AN/SPY-1D only
one, belowdecks, so its failure is a mission kill for the ship. Great, but
how can be that considered a negative aspect of an AEGIS system is
something that puzzles me. We shouldn't forget that if the ship service
turbo or aux generator fails, because of the sustained battle-damage, the
active array will remain as silent as a passive one. Doh! And... what if
the technology on passive array like AN/SPY-1x, and specially the software
of its fire control system, is more mature than the one on new-generation
barely-tested almost prototype-alike active arrays? Would that offer
additional, realistic, operational reliability?
c) Performance on littoral/enclosed waters and low horizon scanning. This
is due to the capability of forming narrower beams at low angles. Great,
but let us not forget that this ability depends also on the frequency that
the active/passive array is using. I would like to remind that
AN/SPY-1D(V) is modified for the littoral environment and for dealing with
fast, sea-skimming missiles. We have to remember that a _fixed_ array has
the capability of changing its beam scheduling/policy to hit low-elevation
sectors at will, something that is not as easy in a rotator active array
like the British SAMPSON, or passive one like ARABEL/EMPAR. The same can
be said to higher-elevation sector scans for ballistic missile defence
(TBMD).
So, as you can see there are a number of _theoretical_ advantages on the
active arrays, but none of them is prone to revolutionize anti-air warfare
any time soon. Upon a close examination, the most interesting ability is
the one I mentioned in point b), and that surely is not one that can
substantiate the very frequent British claim that SAMPSON is "better" than
anything on earth. There are plenty of naval/ground late generations
passive arrays being fielded/designed (SPY-1, TRS-22XX, RAT-31SL, EMPAR,
ARABEL, Sky Watch, J/FPS-2, Type320 etc), a fact that confirms their
capability is absolutely granted in their lifetime. On the other hand, a
few additional comments:
- German/Ducth F-124/LCF Side. We are not sure that APAR-STIR/SMART-L is
inferior to AN/SPY-1D, but it doesn't look superior either. For a start,
one of the most important functions of the ship (long range volume search)
is assigned to the Delta-band rotator SMART-L. A rotator is prone to
mechanical failure and it's sensible to special kinds of countermeasures
(more of its sidelobes are exposed on every rotation). So two of the
advantages of the active APAR system (reliability through progressive
degradation and ECCM) could be moot points if balanced with the
disadvantage of SMART-L. Second, a rotator will _never_ be as efficient in
littoral areas or in TBMD (where long range volume search is vital) as a
fixed array with beam scheduling. Third, SMART-L is forcing you to have a
bigger radar cross section (RCS) than with a single fixed array that
combine search and mid-course guidance. Fourth, APAR is very nice, but is
working in a higher frequency (India-band) than SPY-1D, since it's
basically a fire control radar. That means shorter range, worse weather
penetration and clutter rejection, which implies that your backup
volume-search in case of SMART-L _mechanical_ failure is compromised.
Having APAR/SMART-L could look like a nice redundancy feature, until close
examination: if you loose APAR you are mission-kill due to FCS loss, but
if you loose SMART-L, you have your early warning detection and volume
search on an India-band fire control radar! Uh-oh, looks like a mission
kill to me. Fifth, if your want to integrate SM-2IVA and CEC you have to
pay for its development. None of that applies to the F-100's AN/SPY-1D.
(It could be argued that the AN/SPG-62 of the Mk.99 AEGIS FCS can also
suffer mechanical failures, but remember that such end-game India-band CW
illuminator is not subject to same mechanical stress as a constant
long-range search rotator).
- French/Italian ARABEL/EMPAR side. With due respect, though nice and
modern radars, their overall capability is not even in the same league as
AN/SPY-1D (though it must be said that EMPAR _looks_ better than ARABEL,
at least on paper). For a start both ARABEL/EMPAR are passive phased array
mechanical rotators. That implies bigger RCS, bigger still due to the use
of a second rotator S1850M (SMART-L/MARTELLO coctel), for long-range
volume search. It also implies worser data rate than a fixed array like
APAR or AN/SPY-1x. The same problems described in the previous paragraph
regarding the rotator SMART-L can be applied to these systems, with
increased manning costs to maintain two mechanical radar systems instead
of a single reliable fixed one like SPY-1x. In addition, both of them are
higher frequency (specially ARABEL, since EMPAR is Golf-band, but still a
mere 80Km range or 150Km with dedicated surveillance and decreased data
rate), and that implies shorter range, worser clutter rejection etc.
ARABEL/EMPAR are not even a multibeam radar like SPY-1x, though they can
change the beam from pulse to pulse. (No mention goes to the use of Sylver
and the need to get rid of the 5" gun to make space for the missiles!)
- British SAMPSON side. Again, a much vaunted active array evolved from
MESAR/TRISAR/TRIXAR, with all its theoretical advantages, which are a lot
bigger on paper than on practice. But... an active phased array on a
rotator? Again, in order to reduce cost your get worse data-rate, even if
you use a back-to-back configuration and sophisticated beam steering.
Again, it needs a second radar for PAAMS volume search, with all the
implications previously described. Additional maintenance. Bigger RCS,
etc. But the most important thing is, we have AN/SPY-1x today. We know it
works. Where is SAMPSON and its associated FCS? How can be the advantages
of something that doesn't exist be analyzed?
Cutting long stories short, I agree that APAR _looks_ very nice, and we
only got out of it because there were some initial problems and doubts.
Also, SAMPSON _looks_ good on paper, but it will take many years to reach
full operational reliability. The most important thing that Iñigo wants to
say is that the AEGIS combat system is very mature and proven technology,
with a minimum technological risk and development cost for Spain and with
a very promising future through CEC and TBMD. Software is an extremely
complex beast, and I wouln't change the stability of an AEGIS tried and
tested WCS for a newer generation bells-and-whistle one if the decision
was in my hands. The Armada has chosen the best possible solution for
Spain. Taking aside national, political, industrial and darker interests,
the F-100 and its technology could have been the best solution for Italy,
France and the UK. They won't admit it, but they know it, and they suffer
in silence.
Saludos
. O sea, no es un radar que sirva bien para explorar grandes espacios, y es un muy buen sistema de guiado de misiles SARH pero para alcances que no son los máximos logrados por otros sistemas designadores dedicados, muchísimo mas baratos y de mayores potencias y alcances. Lo que si tiene bueno es que tiene gran capacidad de detección y puntería de cualquier objeto aéreo o de superficie y, por su numero de antenas, les puede seguir el rastro constantemente sin perderlos ni dejar de explorar otras zonas (que no es el caso de un radar giratorio mas normal, donde necesariamente lo tiene que perder de vista un rato al objetivo), lo cual es muy importante para la defensa antimisil, especialmente para misiles superstición. Pero entonces, es un radar mas bien de autodefensa (muy efectivo) que de dominio del espacio aéreo (como un SPY-1) y para eso, me parece que hay alternativas mas económicas y menos complicadas. 
.
