radiation absorbing material
Is this the same as what they use in stealth?
radiation absorbing material
There are no perfect absorbers or reflectors of radiation. The best of absorbers will reflect some amount of radiation and the best of reflectors will absorb some amount as well. A radiation shield is usually made of materials that don't allow radar waves to pass through them, radar-opaque objects they are called. Such objects have both absorbing and reflecting properties, some materials are more on the absorber side than reflector and some other materials are opposite. The selection of material is obviously done depending on application.Radiation shields are made up of radiation absorbing material and those wavelength's reflected are of diffient than that of the radar. The sheiding barrier is made in such a way, it not just a reflective surface.
Very similar. You see, if you could absorb all incident radiation you wouldn't need stealth shaping at all. But that can't be done, at least not yet.Is this the same as what they use in stealth?
There are no perfect absorbers or reflectors of radiation. The best of absorbers will reflect some amount of radiation and the best of reflectors will absorb some amount as well.
This radar, like all other radars, will search and track any projectile within its range be that Chinese or someone else's. What the VC11184 brings to the table is that other land based radars as powerful as this(like the Swordfish, LRTR, MOTR in increasing order of power/range) don't is mobility. That mobility allows a wide variety of applications some of which weren't previously possible.So with this radar we will be able to track foreign projectiles as well. Especially China's.
We don't know for certain what radars are present at the foreign based TTC. Since those TTCs are part of ISRO's ISTRAC network it is safe to say they have the PCMC radars. But whether something like the MOTR is present there is not known.But how this radar is different from the ones which ISRO deploys near Asia Pacific for telemetry of LV.
There are no perfect absorbers or reflectors of radiation. The best of absorbers will reflect some amount of radiation and the best of reflectors will absorb some amount as well. A radiation shield is usually made of materials that don't allow radar waves to pass through them, radar-opaque objects they are called. Such objects have both absorbing and reflecting properties, some materials are more on the absorber side than reflector and some other materials are opposite. The selection of material is obviously done depending on application.
Here in lies the problem. The proximity of the shield to the radar means you are dealing with a lot of energy fired from near point blank ranges. As such any radiation shield here will end up being a reflector. There is a limit to how much energy a absorbent can absorb away. going past that limit would mean the absorbent becomes a reflector.
That is an excellent point. Here is my counter :Radar Absorption/deflection is possible, without having much reflection. thanks to the wavelength of operation. Ever seen insides of an anechoic test chamber? that's one way Radar shielding/energy absoption.
Didn't understand this. Could you please elaborate ?I do understand black body radiation. however radars only see what wavelengths they send out and what they expect to see reflected back. to other wavelengts thay are blind, and the Shield is designed to take care of these.
The point I am trying to make is that those polyester sponges are excellent absorbers but still not perfect. They will still reflect some amount of energy.
But still your point stands. Those sponges are excellent absorbers and they would absorb away most of the incident radiation while reflecting a minuscule mount in some random direction. So the question arises if the sponges are so good at absorbing radiation, why aren't they used in stealth aircrafts or ships ? Why the whole drama with RAM/RAP if some good old sponges can get the job done ?
Because their physical properties make them pretty unusable. Imagine these sponges on the VC11184, all we need is a good rain and they are rendered useless. The sponges absorb so much energy because of their huge surface area to weight ratio. Once the gaps are filled with water, they lose their properties. It is simply not practical to carry sponges on ships, exposed to the elements, and expect them to replicate the properties they display in controlled lab test environment.
Didn't understand this. Could you please elaborate ?
This conversation borne out of speculations is now going to curious places.I agree broadly to what you said above except for some areas but we are straying off topic.The reflected energy will not be of the same wavelength of the incident energy. It will be in IR range most likely radars wont pick them up. Also, the radar dome serves a purpose. Aslo Sponges are used in an Anechoic chamber, That was used as an example by me I didn't mean to say they will be using Sponges on an exposed area which they can albeit it will be made of a different material, with the liberty of space and surface design other RAM/Coatings can be used, as there are no such restrictions like aircraft have. The surface coating (RAPs) can be much thicker and applied on varied geometry.
Radar transparent materials like the radome also changes the properties of the wave, so radar manufacturers experimentally account for the losses
Also if the shield's only purpose was to protect the crew from the radiation, why not just use a heavy dose of RAM/coating on the deck and superstructure of the ship ?
True, but I think you are missing the point here. The point is radar equipment, like all other equipment, performs differently in operations than in lab tests. So manufacturers/designers often device various tools/methods to ascertain the real world performance of the equipment. Such tools exist for every kind of equipment. Just because we will have some losses during operations is no reason to think such a system cannot be designed.We are talking about the insertion loss here and not just that the surface of radome must be hydrophobic or else the signal will get attenuated
Reasons for what ? Having the shield ?Other two reasons are
The actuation system of the radar is under the deck of the ship, inside the ship not on the deck. As such the machinery sits in the air-conditioned surroundings of the interiors of the ship not exposed to the elements outside. The AC works quite well you know, recently we've had a single ship going to the freezing Scandinavia on route to St. Petersburg and sail back with no problems. Besides we don't go to freezing waters a lot do we ? Its is quite rare.1. to prevent the movables in radar from icing when sailing in cold water
The orientation of the radar is visually obscured away by the radome. However if you are looking at China from Vietnam's coast, they would probably know anyway. From that distance the radiated energy is too high to hide, even if the radar is sweep scanning(lowest power mode) the Chinese would be able to sense the energy.to hide radar's orientation/direction to which it is facing, for example if the vessel is near Vietnam and radar is facing North West this would mean the surveillance is on China
This conversation borne out of speculations is now going to curious places.I agree broadly to what you said above except for some areas but we are straying off topic.
The initial speculation I made was at the possibility of using the shield as a reflector for radiation and thus using the set up as a OTH radar. I agree that the reflected energy will have different wavelength than the incident radiation, the wavelength will increase after the reflection. But that can always be accounted for. Radar transparent materials like the radome also changes the properties of the wave, so radar manufacturers experimentally account for the losses. Simply put, losses caused by the radome=(energy radiated by the radar without the radome - energy radiated by the radar with the radome). Just like that the reflected energy and losses can also be calculated and accounted for.
The reason why I was going on about the possibility of such a set up being used as a OTH radar is the frequency chart here :
View attachment 10912
The main radar of the VC11184 works in the S-band(IEEE classification) and most OTH radars work in the shortwave(3-30 GHz, lies in the UHF-SHF band) by ITU classification. You will notice that the S-band and UHF/SHF-band has a degree of overlap. So the task at hand for us is to design a reflector that causes the reflected waves to stay in the UHF/SHF band(nothing less than 3.5 GHz), this is not a very difficult task. At most you need a few months of experimentation.
This is why I formed this theory in my head, it seems like a very doable task to me. I could be totally wrong though.
Also if the shield's only purpose was to protect the crew from the radiation, why not just use a heavy dose of RAM/coating on the deck and superstructure of the ship ? Conversely why not just program the radar to not throw radiation in this direction ? Modern day radars are very programmable and there are 2 other radars on the front deck, combined data from all 3 radars should paint a full picture with no bling spots. Another point would be, where are the radiation shields for the front deck radars ? Those 2 radars are very close to the bridge with the crew there all the time.
You are right. Let's stop.bhai.... I wasn't talking about the radome... the radome will ward off some reflection from the shield. I think it not just for the crew but hte ship's Comms and other equipment. The construction constraints may have necessitated such a design. This is all speculation.
These posts would be all in waste if that turns out t be some antenna for communications.
You are right. Let's stop.
Don't give me more ideas, I'll start again. That would be quite anticlimactic though.
Ah....magnificent. She is beautiful, although I do hope it doesn't rain. The crew could probably bath in the water stocked up in those dishes.Savor this Cosmonaut Yuri Gagarin, telemetry tracking ship
YeahReasons for what ? Having the shield ?
The AC works quite well you know, recently we've had a single ship going to the freezing Scandinavia on route to St. Petersburg and sail back with no problems. Besides we don't go to freezing waters a lot do we ? Its is quite rare.
Savor this Cosmonaut Yuri Gagarin, telemetry tracking ship
Yes you can use it for that but there is no need for it. As of now satellite tracking is the work of ISRO's MOTR and PCMC radars(for foreign and domestic satellites respectively). I've written about them on post #522 on this thread :So we can even track the satellites with more precision with that, I mean the one which we are developing.
Yes you can use it for that but there is no need for it. As of now satellite tracking is the work of ISRO's MOTR and PCMC radars(for foreign and domestic satellites respectively). I've written about them on post #522 on this thread :