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 ...
user avatar
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 ...
user avatar
  • 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 ...
user avatar
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 ...
user avatar
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 ...
user avatar
  • 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 ...
user avatar
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, ...
user avatar
  • 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 ...
user avatar
  • 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 ...
user avatar
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.
user avatar
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 (-...
user avatar
  • 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-...
user avatar
  • 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 ...
user avatar
  • 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 ...
user avatar
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 ...
user avatar
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 ...
user avatar
  • 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 ...
user avatar
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 ...
user avatar
  • 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 ...
user avatar
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 ...
user avatar
  • 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 ...
user avatar
  • 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 ...
user avatar
  • 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:
user avatar
  • 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 ...
user avatar
  • 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 ...
user avatar
  • 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 ...
user avatar
  • 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 ...
user avatar
  • 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 ...
user avatar
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 ...
user avatar
  • 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 ...
user avatar
  • 3,891

Only top scored, non community-wiki answers of a minimum length are eligible