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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
6k 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 ...
23
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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/...
17
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2answers
2k 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?
17
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2answers
3k views

Did NASA's Borg Collective-designed antennas work? Have similar designs ever been used in spacecraft beyond testing?

This interesting answer to the question Do antenna farms on spacecraft make any sense or are they purely aesthetic? in Worldbuilding SE links to the NASA Ames page 'Borg' Computer Collective Designs ...
12
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2answers
674 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 ...
8
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1answer
750 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)?
8
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1answer
794 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 ...
7
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2answers
558 views

What are these antenna-like structures seen in Oleg Artemyev twitter video?

Russian Cosmonaut Oleg Artemyev's Sept 3, 2018 tweet has a narrated video of Earth from the ISS, at the time over the Nile river. The video is also in YouTube (below). At the bottom of the screen, ...
7
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1answer
294 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-...
7
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1answer
1k 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, ...
6
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2answers
646 views

What is this spinning object seen on a spacecraft above the ISS?

In the YouTube Trailer for the PBS program A Year in Space at 00:56 a small spinning object can be seen, attached to a spacecraft well above the ISS. I think the ...
6
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2answers
978 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
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2answers
786 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 ...
5
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2answers
133 views

How does the pattern on the MarCo cubesat's antenna boost data-transmission?

I was looking at a few posts that uhoh had made about the MarCo cubesat. One of the pictures was the one that I've posted below: The most I can gather from casual NASA articles is along the lines of: ...
5
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1answer
965 views

Could the Voyager spacecraft be spin-stabilized to keep their high gain antennas pointing towards the Sun (and therefore Earth)?

A suggestion has been made that the Voyagers may run out of propellant and so may not be able to maintain pointing near the Earth for communications. According to @BowlOfRed's answer: Although the ...
5
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2answers
103 views

When scientific and engineering data are sent from space probes, are the signals repeated to minimize transmission error?

I would think that this would be the case. In any one transmission there will be a systematic error due to the fundamentals of the transmitter / receiver. Is there also a transient or stochastic error ...
5
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1answer
278 views

Deep space craft antenna aiming

In order to aim an antenna at Earth, how do unmanned spacecraft find their own orientation (xyz position in space, what direction it is flying and which direction the antenna is pointing)? Are they ...
5
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1answer
336 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, ...
5
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1answer
427 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, ...
5
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1answer
124 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?
5
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0answers
80 views

When did deep-space probes start getting wrapped in germanium-coated film?

The NASA video Juno Engineering: Precision Matters shows the Juno spacecraft on what look like it might be a spin balance table after about 02:50 and there one can ...
4
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1answer
82 views

Why do GEO satellites need different types of antenna?

Why do GEO satellites like the one shown in the picture below need different types of antenna? Is there a reference library or website where we can get more information on different antenna types, ...
4
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1answer
165 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 ...
4
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1answer
820 views

How does SpaceX Falcon Heavy Starman live feed transmitter work?

I'm curious to find out answers to the following questions: Where is the antenna for the live feed transmitter of starman located in the payload? How is the transmitter being powered? Related to 2nd ...
3
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3answers
354 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 ...
3
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2answers
469 views

Can't we use laser transmitters instead of large radio dishes on deep space probes?

Isn't it possible to use a laser as an "antenna" that transmits data? This would save quite a lot of mass since you don't need a large dish. The only problem I can think of is how would you modulate ...
3
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2answers
1k 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 ...
3
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1answer
257 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 ...
3
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1answer
100 views

How do you calculate the lat and lon of a point on the earth using azimuth and elevation seen from a geostationary satellite?

I am given the longitude of a geostationary satellite and a pointing vector from the satellite in the form of azimuth and elevation angles looking from the satellite towards the earth (where zero ...
3
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0answers
97 views

How would the antenna on a spacecraft in GEO be provided an electrical ground?

I would like to understand better what specifications or guidelines address the electrical grounding/Earthing a parabolic reflector Antenna in GEO to minimize the potential difference with respect to ...
3
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0answers
61 views

What is the Telescope Invariant Point?

I am working on an implementation of an SLR tool. At some points of the documentation of the CRD format the term telescope invariant point shows up. Apparently it's a point on an ILRS antenna system. ...
2
votes
1answer
86 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 ...
2
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1answer
68 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
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1answer
84 views

Need help identifying this (likely to be) phased array antenna used to track launches

I need help identifying the (what I believe to be) flat (and possibly phased) array antenna shown next to the tracking telescope in this photo, which can be found both here and here where the ...
2
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1answer
399 views

What is Canted Turnstile Antenna System? What it its Applications?

There are not many sources I can read to know about this kind of Antenna and its Applications
2
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1answer
274 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 ...
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0answers
50 views

Was there a prototype for Solar Probe's hybrid Heat Shield/Antenna?

An early concept of the Solar Probe (reborn as Solar Probe Plus then Parker Solar Probe) used a parabolic antenna with a heat-resistant nadir facing side to double as a heat shield. While sourcing ...
2
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0answers
94 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
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3answers
376 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'...
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2answers
144 views

What is this combination tracking telescope and helical antenna pair? was it really used, and who is/was FlightLine?

I spotted the image below here which I found here (also seen here). Zooming in on this combination pair of telescope trackers and pair of RHCP and LHCP (right- and left-handed circular polarization) ...
1
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1answer
184 views

What are these dishes looking at?

In this CSA video CSA Astronaut Chris Hadfield describes the attitude control of the ISS and its importance for things like communication with Earth. At 00:30 here ...
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2answers
1k views

Angular distance between two satellites given azimuth and elevation angles for each?

If the look angles for a pair of satellites are $Az_1, El_1$ and $Az_2, El_2$, what would be the angular separation between them? An associated problem is how do we determine whether and when the two ...
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1answer
36 views

Is OSIRIS-REx's high gain antenna nearly the same as TESS'? If so, why?

These two high gain antennas look very similar superficially, but are not identical. Is this a case of convergent design (a fancy kind of coincidence) or have they evolved from the same source, or ...
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2answers
127 views

Did New Horizons use its smaller medium-gain antenna for most/all downlinking of Pluto and Ultima Thule flyby data?

Brian May's New Horizons video (below) was released at about the same time that the New Horizions spacecraft passed 2014 MU69 Ultima Thule and includes a lot of technically meaningful graphics. One ...
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1answer
105 views

What kind of ground-based radio astronomy is NASA's DSN used for? Who are the PIs?

I looked at DNS Now to check on Hayabusa-2 and compare to http://haya2now.jp/en.html and saw that DSS 34 in Canberra is currently in setup/teardown for Ground Based Radio Astronomy! In this status ...
1
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1answer
103 views

How do Inmarsat 5 F4's beams correspond to all of these antennas and feeds?

note: This is an old-style @uhoh question meaning that it is a bit on the long side. In this case I think it really needs to be since the question is a bit complex; I'm trying to understand how all ...
1
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1answer
147 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 ...
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0answers
31 views

E,H Plane beamwidth of planar arrays in YZ plane [closed]

When a planar array is in XYplane I found out beamwidths are matching with the Balanis text book results.I kept the array in YZ plane the beamwidths are different in this case.Can any one help me ...
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0answers
30 views

How video projection screen is used in test of Europa Clipper's high gain antenna?

Phys.org's Europa Clipper high-gain antenna undergoes testing says: The full-scale prototype antenna, which at 10 feet (3 meters) tall is the same height as a standard basketball hoop, is in the ...
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0answers
78 views

Calibration of Antennae in satellite and in ground station [closed]

How to orient the ground station antenna and that of the satellite just after the launch?