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Questions tagged [antenna]

Questions about devices which collect and couple electromagnetic signals (communications, radar or other electromagnetic measurements) directly between free space, and conductors (e.g. waveguides or other transmission lines).

24
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2answers
5k views

What is the purpose of the rotating dish antenna on the ISS

I just saw some footage of the ISS in which a dish antenna could be seen, constantly rotating. The dish looked more-or-less parabolic, meaning that it is presumably sending/receiving along a fairly ...
17
votes
2answers
1k views

Why did Sputnik 1 have four antennas?

Sputnik was only launched a few hundred kilometers above Earth, and transmitted only a simple beeping signal. What was the purpose of having four antennas? Wouldn't one be powerful enough?
7
votes
1answer
904 views

Why is TESS' high gain antenna made of undulating BLACK fabric rather than metal?

above: from Facebook, then annotated. There is an excellent review of the design of the TESS spacecraft in G. R. Richter et al. Journal of Astronomical Telescopes, ...
8
votes
1answer
693 views

When is a phased array antenna not a phased array?

This question is inspired by an answer to this question, where it is stated that: The real power of phased arrays is their ability to be steered electronically. This set me wondering about the ...
3
votes
1answer
229 views

What were those motorized human-piloted platforms with helical antennas called (tracking launches)?

This interesting question got me started. I have these vignettes in my Apollo-era memory of antenna systems that tracked launches for telemetry. They had maybe four end-fire helical antennas pointing ...
2
votes
1answer
219 views

Will there be “Near Space” Ka band allocations for TESS?

update: More information in Phys.org's news item TESS mission to discover new planets moves toward launch, including a video of the telescope array's final assembly. Also see GSFC's TESS page. The ...
5
votes
1answer
276 views

How does Curiosity know how to point and move it's high gain antenna in real time?

The Curiosity rover has a compact X-band high-gain antenna (HGA) that allows for low data rate communication directly with Earth, but is used mostly for higher data rates to spacecraft orbiting Mars, ...
3
votes
2answers
644 views

How to design a ground antenna for sending & receiving from a satellite?

Let's suppose there is a wifi router or a cell phone or similar transmitter in an orbit of 3000 km. How could one make a dish antenna to connect and receive the signal from that wifi router or cell ...
23
votes
2answers
3k views

What is the function of this (apparently) fixed dish on the ISS?

I saw this image in Popular Science, one of the example photos from the book by astronaut/photographer/astrophotographer(?) Donald Pettit. It's beautiful and impressive not only from a color/...
8
votes
1answer
652 views

Radiation pattern and signal strength of navigation satellite antennas

Where can I find the actual radiation pattern and signal strength of transmitting antennas used by GNSS navigation satellites/constellations (GPS, GLONASS, IRNSS, etc)?
6
votes
2answers
941 views

How did this structure fit into the Shuttle and then expand to 28 meters?

In this answer I read about the Inflatable Antenna Experiment that flew with STS-77. According to this article: Packed into the Spartan, the IAE weighed only 132 pounds; on deployment (inflation), ...
6
votes
1answer
339 views

How is GAIA's phased array configured, mechanically and electrically?

GAIA is an amazing pair of space telescopes that share a single Gigapixel CCD array, with a complex optical system capable of repeated, extremely precise position, brightness, parallax, proper motion, ...
3
votes
3answers
190 views

What is the largest antenna deployed in space?

@Tristan's answer says: The satellites are classified, so details are speculative, but it is believed that the Magnum/Orion and Mentor SIGINT satellites have parabolic antennae around 100 m in ...
2
votes
1answer
64 views

What's the largest area dish antenna sent beyond the Earth-Moon system?

In the same vein as the question What's the largest aperture telescope sent beyond the Earth-Moon system?, I'd like to ask, what's the largest area antenna dish sent beyond the Earth-Moon system? If ...
1
vote
3answers
245 views

Why were the antennas on the spherical surface of some early satellites spiral-shaped?

In the question What's the spiral pattern on this satellite? I show this image of a spiral-shaped pattern on the spherical surface of a (presumably) vintage satellite or model thereof. @OrganicMarble'...
12
votes
2answers
643 views

What is the large circular device with a dozen concentric circles on Sentinel 3B?

The Spaceflight Now article Photos: Sentinel 3B satellite prepared for launch from Plesetsk Cosmodrome has of course lots of photos. One of them shows a dish antenna covered with shiny, metallized ...
6
votes
2answers
662 views

How are phased array antennas used in spaceflight? Benefits and limitations

It would seem to me that a phased array antenna would be great for spacecrafts since it removes the need to turn the entire spacecraft around in order to point the radio dish towards Earth. Many ...
8
votes
1answer
258 views

How do commercial broadcast satellites in GEO produce such carefully shaped signal footprints?

SES-10 will be launched in a few days on Space-X's first commercial launch using a recycled rocket. Screenshots from the three links (Brazil, Central America, South America) on Satbeams page for SES-...
5
votes
1answer
91 views

What happened to the plan to build a DSN antenna array?

More than ten years ago there were plans to build large antenna arrays for DSN, about 400 antennas of 12m diameter. See these NASA papers 1, 2, 3, 4. What happened to these plans?
4
votes
1answer
157 views

The appearance of TESS' dish seems to be evolving, what will be the final configuration?

The question Why is TESS' high gain antenna made of undulating BLACK fabric rather than metal? has had three bounties, and is probably the recipient of this sites longest answer. My personal pet ...
2
votes
1answer
50 views

Function and nature of the RHC/LCH pair of cables to New Horizons's dish antenna secondary mirror?

Spaceflight 101's New Horizons Spacecraft Overview is full of interesting information and shows this RF Comm System Block Diagram. The thin (red) lines to the dish antenna area are coaxial cables and ...
2
votes
0answers
74 views

Did any of Voyagers' receivers' front ends take advantage of the “cold of space” to lower noise?

Most of the Voyagers' electronics are kept warm by electrical heaters powered by their RTG's, and presumably protected by some amount of insulation from the "cold of space" which means loss of heat ...
1
vote
1answer
117 views

How does this antenna work, with both a feed horn and hyperbolic secondary in front of the dish?

Scrolling through the Roscosmos twitter feed I saw this image of a dish antenna in a recent tweet. Google translate shows that the post says: Новый измерительный пункт будет построен на Сахалине ...