16
votes
Accepted
Faraday cage in Microwave oven
No, your oven does not have a dangerous leak. It is designed to only contain only the frequency used by the magnetron (2.45 GHz). The frequency bands used by cell phones are very different.
In ...
- 1,210
8
votes
Accepted
Designing a helical antenna for a dish
I haven't built one of these myself, but one of the best resources I know of for the theory is antenna-theory. The second page mostly discusses gain. There it talks about optimizing the distance ...
- 9,275
7
votes
How to create a simple 1296MHz transmitter?
So, there's a bit of disappointment I'll have to spread here:
Building microwave circuits like the one you need isn't per se as easy as just scaling up a circuit for, say 3 MHz or 100 MHz.
Let's ...
- 13.5k
7
votes
What are the properties of the radiation of a magnetron?
I'm sorry if this answer doesn't answer your literal questions – it's just that these questions aren't strictly answerable.
it is commonly known that electromagnetic radiation from an antenna is ...
- 13.5k
7
votes
Accepted
What type of omnidirectional antenna gives the most gain for a frequency of 2.4 GHz?
An antenna can't "amplify" a signal, it can only concentrate it in certain directions. If you want a peak gain of 15 dB (about 30x the power density of an isotropic radiator), you can only ...
- 9,275
6
votes
why fiber optics replaced microwave
Microwave technology isn't superior. That's why it's abandoned.
Optical links are much faster. A single, inexpensive fiber optic cable easily delivers a bitrate of 1000 Mb/s, while a bundle of fibers ...
- 50.1k
6
votes
Why can't we use a simple wire for receiving 2.4 GHz signals?
It might be a good idea to start by trying to make a block diagram of what you have inside of each of those controllers...
Namely, the drone controller is most likely some sort of a system on a chip, ...
- 2,715
6
votes
Accepted
Why can't we use a simple wire for receiving 2.4 GHz signals?
A wire will pick up a GHz signal, as well as a ton of other RF signals, all mixed together. Some sort of filtering is required to separate out your desired radio signals. An Arduino has none of ...
- 12.5k
5
votes
Accepted
Linksys WRT54G turned in to a brick
After a long time pondering about this, I realized the trick. The first problem is that I had a version 3v of the router, and I installed the 3g version of the ...
- 5,973
5
votes
Is this result correct ? [ impedance cavity based on emtamaterials using CST Microwave]
Antenna efficiency over 130% would mean a perpetual motion machine, so probably not.
- 50.1k
5
votes
Failing to detect Hydrogen line with 105cm dish
The sawbird H+ looks like a nice LNA, do you have the H+ H1 version?
The plan version seems to be for 1542 MHz, "center frequency of the module is 1.542GHz with approximately 80MHz of bandwidth (-...
- 8,235
4
votes
How to build the smallest directional antenna (ISM band)?
(Sorry about the long delay)
An antenna that might meet your requirements is called the HB9CV. It's an array with two dipoles about 1/4 wave apart, driven with the correct current that they add in-...
- 8,235
4
votes
Accepted
What is a general procedure for aligning directional antennas?
Use a map and a compass.
Really. It doesn't have to be more involved than that. As long as we are talking about line of sight propagation, that should be close enough to get you well within the ...
- 4,810
4
votes
Troposcatter: really all that bad?
Troposcatter is the common mode for beyond line of sight on the 10 GHz ham band when the band is not otherwise open, good for 100's of miles. A radio with just a few watts output power and a ...
- 41
4
votes
Accepted
Why are FM radio waves less susceptible to interference than AM?
The waves (to be correct: the signals) are exactly as suspectable to noise for both modulations!
What's different is the receiver:
As the name suggests, Amplitude Modulation (AM) works by taking the ...
- 13.5k
4
votes
Accepted
How to calculate Return loss of cascaded system?
Assuming the systems have no internal loss.
Reflected power ratio for system 1 is 0.1, for system 2 is 0.01.
$ = \Gamma^2 = 10^{-RL/10}$
Power transmitted ratio for system 1 is 0.9, for system 2 is ...
- 56
4
votes
Applications for 100 GHz band?
Aside from what Zeiss Ikon wrote, these high frequencies are indeed also interesting for communications technology, for very high-rate and typically narrow-range links.
For example, in cellular ...
- 13.5k
4
votes
3D Printed yagi antenna
Some general hints from my experience:
Use wires not printed metal. You could stop the print for a while to drop in the wires, then finish it, or push them in later. For sanity's sake, design your ...
- 8,235
4
votes
Maximum frequency for discrete components bandpass filter
Lumped elements are theoretical constructs from the lumped element model. So you can't really build a filter from lumped elements at any frequency.
But, you can ask at what frequency discrete ...
- 50.1k
3
votes
2.45GHz: constructing a horn of *thin* steel, what are good ways to join the edges (at least one joint along corner?)
I'm no expert on sheet metal fabrication and hopefully someone will come along with a more confident one, but in general I would expect that soldering/brazing is the correct answer.
(solder in ...
- 23.1k
3
votes
Wifi inside a rocket
The biggest issue between stages is that wifi doesn't penetrate metal well. Engine bells and plumbing are generally metal, even if tanks and exterior airframe skin aren't. Since cables are highly ...
- 3,891
3
votes
2.45GHz: constructing a horn of *thin* steel, what are good ways to join the edges (at least one joint along corner?)
For very narrow gauge, as in the sheet metal used for the waveguide in a microwave oven I think it's a process involving a roller disc inside the waveguide making spot welds at the closest interval ...
- 238
3
votes
What are the parameters and necessary features of a Gunn diode oscillator cavity?
You might be able to use this mechanical drawing, from the ARRL's monthly QST magazine for August 1974, to determine whether the available units are appropriate to your needs:
- 7,693
3
votes
How to calculate Return loss of cascaded system?
Some time as passed since the original posting and I suppose the student has lost interest in this problem. But for the sake of completeness, I offer the following.
It must be said (as other ...
- 18.2k
3
votes
Maximum frequency for discrete components bandpass filter
Two datapoints that might help:
A previous company we had a 20-6000 MHz diplexer with a changeover at about 900 MHz, using 0402 parts. Some trial and error to get it to match the simulated design.
A ...
- 8,235
2
votes
Accepted
What is the best approach for measuring return loss of a home-made 3cm horn?
The circulator is the most sensitive method, because all of the reflected power goes to the power meter.
Some thoughts:
Are you sure that the circulator is working correctly at your frequency? Any ...
- 8,235
2
votes
RF inert adhesive for building antennas in the UHF to low GHz region
Take a look at Epic Resins. They have epoxies and potting compounds that are characterized into the GHz range. Master Bond is another possible source.
Do be aware that when assembling antennas using ...
- 18.2k
2
votes
Accepted
Troposcatter: really all that bad?
I don't think a better answer will come along, so I'll summarize a combination of assembled anecdotes and opinion.
As far as I can tell, your calculations are accurate. I did a little research for ...
- 50.1k
2
votes
Accepted
What is this large, flat microwave coaxial connector?
Martin Ewing AA6E got it right in his comments on the question, which he hasn't posted as an answer yet himself so I'm copying here for the record:
Can't verify the dimensions, but is it possible ...
- 23.1k
2
votes
Applications for 100 GHz band?
A frequency of 100 GHz is equivalent to a 3 mm wavelength; these "millimeter waves" have been used for decades in airborne radars. The short wavelength allows a narrow beam and excellent gain from a ...
- 3,891
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