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Seems like an error in the article. [1] states: "FreeFall’s antenna technology is unique because it is using a spherical reflector. In the past, antennas alway
by guenthert 3y ago
Seems like an error in the article. [1] states:
"FreeFall’s antenna technology is unique because it is using a spherical reflector. In the past, antennas always used a parabolic antenna. A parabolic antenna focuses energy to a “single point” – while a spherical antenna focuses energy to a “focal line”. Parabolic antennas are symmetric about only one axis which severely limits field of view. It also requires precise pointing for high gain and has more complex packaging, deployment and on-orbit operations.
The spherical antenna provides a wider field of view for antennas and high gain without re-pointing of an antenna. Combining a spherical antennas with inflatables is the key to achieving a large aperture in a simple lightweight system."
[1] https://www.freefallaerospace.com/nasa-balloon/ https://www.freefallaerospace.com/nasa-balloon/
- Intralexical 3y agoArecibo is/was spherical Ftr, presumably because a paraboloid could only sweep a single path through space. They aimed it by moving the receiver.
- denton-scratch 3y agoThank you. I'm not up to date on telescope design (by at least 40 years), but the Cassegrain design used a spherical mirror, I think. It was used for wide-field astrophotography, and (again, I think) it has a curved focal field, so it needs a curved sensor. I'm certain that Cassegrain designs have been obsoleted. I'm just bragging about what an anachronism I am. [Edit] The Cassegrain design also requires a refracting lens in front of the mirror; and the lens is a peculiar shape. [Edit again] I may be thinking of a Schmitt. I've never played with anything more interesting than a Newtonian; I was just an amateur stargazer. All these fancy designs were made for professional astronomers. For me, they were strictly theoretical.