HOLO materials

[MfA]

Controlling both amplitude and phase of a transmitter array is a rather trivial variation on the phased array (I imagine the more advanced "phased array" radar systems already do so). Of course depending on wavelength and size of the hologram this approach could get rather costly.

There is a special setup of phase holograms which allows you to emulate a full amplitude/phase hologram called the tandem hologram ... you could CNC a shape and apply a metal coating to create the phase holograms. See the paper "Near-perfect hologram reconstruction with a spatial light modulator" (obviously the lens in their setup would have to be replaced with a dish).

I am curious though ... why do you want to exactly reconstruct a RF wavefront so badly?

PS. oops, I was a couple orders of magnitude off with my CNC suggestion ... at MHz wavelengths the depth of the fringes for a reflective phase hologram would be on the order of meters ... was thinking mm waves more than meter waves.

[jnhong]

You just suggested that he create a dummy aircraft or vehicle to spoof the incoming radar. The neat thing is that it works for 2-meter all the way to microwave.

[MfA]

You just suggested that he create a dummy aircraft or vehicle to spoof the incoming radar.

No not really, you can reproduce an arbitrary wavefront using hologram fringes of maximum 1 wavelength depth. So it can still be more compact than the actual object ... still, an embossed hologram for meter wavelengths is a bit awkward.

It's going to be hugely costly whatever you do simply because of size so a transmitter array with full phase/amplitude control for individual elements seems the most appropriate solution.

[fefe]

thanks for all ideas and help. But can you post me some helpful links about materials used for recording and etc. ?

[jnhong]

thanks for all ideas and help. But can you post me some helpful links about materials used for recording and etc. ?

Maybe you should explain more about your experiment. What do you want to record and how do you wish to reconstruct it? If you don't know what you want to achieve, how do you know if the answers will be applicable or not?

You need to provide sufficient details. Even with regular visible-light holography, we usually consider the exact wavelengths to use for recording. For example, red (630 nm to 670 nm), green (532 nm), and so on. Exactly what kinds of objects are you planning to record? You don't even know if you want to do THz, GHz, or MHz. And if you do, can you explain precisely how you will illuminate the object and how you will create a reference beam? Or did you intend for the internet to give you all these homework answers as well?

[MfA]

thanks for all ideas and help. But can you post me some helpful links about materials used for recording and etc. ?

You can't record in the traditional sense ... you are talking about something 10s of meters in diameter, you can't image small objects with meter waves, and I very much doubt there are any mediums which can record/replay at those wavelengths.