0
$\begingroup$

I've seen many cameras and photographs of light in infrared, visible, and ultraviolet. And many photos of space in all areas of the EMS. Are there any photos of landscapes or architecture in microwave radiation?

Really curious to what it would look like, as microwaves are so big in comparison.

Googling "microwave photography" yeilds images of fancy microwave ovens, ahah.

$\endgroup$
3
$\begingroup$

Microwave "photographs" are taken with synthetic aperture radars (SAR). This is a pulsed coherent radar in which many pulses are combined to synthesize a much larger aperture, thereby increasing the resolution. The theoretical limit on the resolution is $\lambda/2$, and is independent of distance to the imaged target. (See radar images of asteroids, where there are 15m pixels at 100,000's of kilometers).

Signal delay yields range information, as with any radar. The radars are generally side-looking, so that Doppler information can provide azimuthal (roughly orthogonal to range) information--thereby producing a picture.

Note that GPS and other nav tools on the platforms allow these images to be produces in a absolute coordinate system.

Additionally, 2 receive antenna can allow detail signal phase comparison, allowing a 3-dimensional reconstruction of the scattering surface (very analogous to a laser hologram). This is called InSAR (Interferometric SAR). In the case of more complex surfaces, where there is some penetration, say a forest, ice, or dry sand--radar energy is scattered from multiple depths (volumetric scattering), and by using multiple baseline InSAR, the volume can be reconstructed, in addition to the 3D surface, so it's kinda 3D+.

Different types of processing can also yield line-of-sight pixel-wises velocity information in the imaged region.

Generally, images are single frequency, so they are black and white. Being coherent, they have inherent speckle noise (like a sonogram), so they are often not too ascetically pleasing (I mean compare with the Hubble Telescope in a funding-type situation). Multiple frequency systems, or systems employing polarization can produce false color images with lots of information in them. Typical polarized systems use linear polarization, and the Transmit-Receive channels are HH, VV, HV, where H (V) is horizontal (vertical) with respect to the surface.

Finally: to answer your question. Since SAR images can be collected from space, day or night, in all weather conditions: they can be extremely candid.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.