15

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 particular, the door "seals" are rather frequency-selective. Instead of trying to maintain a good electrical contact between the door and the rest of the oven box, ...


9

I'm going to make an educated guess and say no. Here's my reasoning: Consider the difficulty in just communicating with a satellite. See What is a link budget, and how do I make one? or What gain do I need to talk to SO-50 with my HT? Geostationary orbit is much farther away than SO-50 and thus requires more gain, or more power. Now if we are using this ...


8

You can simulate. The idea is to model your RF channel(s) numerically by adding things like AWGN, multipath, clock skew, and so on. And, you want a way to model a lot of these channels, and twiddle the parameters and see how the system responds. There are many software libraries out there that will make this easier. I'd suggest GNU Radio. It has blocks that ...


8

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 between the feed antenna and the dish, given a fixed pattern for the feed antenna, but basically the same thing applies to narrowing or widening the pattern of the ...


7

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 assume we start with CW and hence just need an oscillator (and a switch). So, let's do, say, a Colpitts, right? Well, sure, but the problem is that it's ...


7

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 polarized; the electric field is parallel to the rod and the magnetic component is perpendicular to it. It is commonly known that antennas come in more shapes than ...


6

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, which on its own chip, in addition to having a microcontroller also has the radio interface built in. Those are two separate things, but in one package. ...


6

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 filtering required. Sampling a 2.4 GHz signal requires a sample rate above 5 billion samples per second. The A/D on an Arduino samples at a rate of about 9000 ...


5

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 software. That doesn't work at all. I should have used the file bbhn-1.1.2-wrt54g-2.4-squashfs.bin instead of bbhn-1.1.2-wrt54g3g-2.4-squashfs.bin (For the latest, probably something different for the ...


5

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 designed for telecommunications can deliver over 10,000,000 Mb/s. For comparison, a modern high-speed microwave link like AirFiber manages a maximum of about ...


5

Antenna efficiency over 130% would mean a perpetual motion machine, so probably not.


4

(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-phase in the forward direction, and completely out of phase in the backward direction. Getting the currents to do this isn't trivial, because they interact with ...


4

There was a conversation that I saw once about what it would take to bounce a signal off of the ISS, which is much closer and larger than GEO satellites. The area is approximately $400\,\mathrm{m}^2$, but varies significantly depending on the orientation of the arrays. That figure should be good enough for now. Let's assume a distance of between 400 and ...


4

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 ballpark unless this is about hugely directional antennas (as in, beam widths of perhaps 10° or narrower in the horizontal plane), and even if that's the case, it ...


4

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 input (audio) signal, and using its strength, to modify the amplitude of your carrier wave. The AM receiver hence only has the amplitude of the received signal ...


4

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 0.99 $ = 1-\Gamma^2$ The first reflection back from each system will be the largest and subsequent reflections will be heavily attenuated, so we approximate by ...


4

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 moderate sized dish (60cm or more) gets enough ERP for troposcatter. For a few random references, check out: Pages 64-70 of http://www.mike-willis.com/Tutorial/RT%...


4

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 mobile communications ("phones"), 5G specifies the "New Radio", which includes using several mmWave bands, the highest among them spanning 37 – 40 GHz. The ...


3

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 reality would be hard to do, it running all over the place or being lumpy.) From what I have seen of soldering large metal parts (with a torch, not an iron), with ...


3

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 reliable, it's worth having the weight to avoid dropouts when flight conditions add enough interference on top of the signal blockage to cut off your guidance at ...


3

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:


3

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 commentators mentioned) that the problem as stated lacks sufficient information to give an exact result. Given more scattering parameters of each system, a conversion ...


3

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 possible and doing multiple passes until it's continuous. People reviewing TIG welders on YouTube routinely weld razor blades together. Any thin steel that's ...


2

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 this is a diode detector? Maybe you can gently pull out the gold piece and find that it's the base of a 1N23 or similar. I'm guessing it's not really a connector, ...


2

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 dish that can fit inside the nose of a fighter aircraft, allowing a forward-looking radar with mechanical sweep to be used without disturbing the aerodynamics ...


2

What you are describing is a directional antenna for your phone. You can do this by placing the phone Inside the antenna, or by connecting the antenna to the phone. The pipe you describe is actually used as an antenna - google for the Cantenna wifi antenna made from a pringles can. A horn antenna like this might not be the most elegant antenna for a phone ...


2

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 issues with it will come out in the results. It is best to pad the source and the power meter, with 6 to 10 dB attenuators, to improve their own matching so ...


2

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 epoxy, that it can act as a dielectric material. This can affect the primary design parameters of the antenna.


2

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 Can tropospheric scatter effect be used by 802.11 links? and determined the requirements aren't absurd, and at least within the grasp of a typical amateur. ...


2

For really fine control of soldering, use a soldering gun as a resistance welder. Just cut off the end of the heating tip, so that instead of a loop you have two big copper wires coming out of the gun. Press them onto either side of the joint and pull the trigger. The current passing through the metal will quickly heat it to the point where it will melt the ...


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