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8 votes

Active RF signal repeater

First of all, your transmitter A would be illegal. And any conductive surface reflects electromagnetic waves; at 10 MHz, a sufficiently large metal sheet would do; there's no point in an active ...
Marcus Müller's user avatar
6 votes
Accepted

Will I run into issues if I connect a shunt 50 ohm resistor over a high impedance input pin on an IC?

Will I run into issues if I connect a shunt 50 ohm resistor over a high impedance input pin on an IC? One result that may or may not be an "issue" is that the voltage at the high impedance ...
Math Keeps Me Busy's user avatar
6 votes

How should I interpret the impedance of an SMA connector?

Transmission lines work like this- they have a characteristic impedance that is (ideally) a certain real number, in this case 50Ω. When you connect two transmission lines (and here the connector is ...
Spehro Pefhany's user avatar
6 votes
Accepted

How should I interpret the impedance of an SMA connector?

It's both the impedance of the connector alone, and the impedance of the connector plus cable, and the impedance of the connector plus cable plus another connector, and so on. The characteristic ...
Hearth's user avatar
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4 votes
Accepted

RF receiver frizzes when start brushless motor

Note that both the Arduino, ESC and RF modules use the same ground, (I think that's the problem). Yeah, quite possibly... or more to the point, the problem is there is no ground, it's all spaghetti. ...
Tim Williams's user avatar
  • 39.2k
4 votes

RF receiver frizzes when start brushless motor

It sounds like you may be getting RF interference from the motors and/or their drivers. There are several ways to deal with RF interference: Distance - keep the source of interference physically far ...
GodJihyo's user avatar
  • 24.7k
3 votes
Accepted

RF power transmission control in U-blox GSM modules

Power control is between your user equipment and the base station, not really in your control – in other words: in all likelihood, this is already done without you doing anything. It's very much in ...
Marcus Müller's user avatar
2 votes

How can a Class E Power Amplifier be built and experimented with safely?

basically be very carefull Follow the same advice given to those working with vacuum tubes. rubber shoes and one hand behind your back.
Jasen  Слава Україні's user avatar
2 votes
Accepted

Are there any LTspice models for OP AMPS with GHz bandwidth?

You will get opamps with GhZ BW. This is one of them. Spice models are available at "Tools & Simulations 2" section. You can import that spice models to Ltspice
Confused's user avatar
  • 2,583
2 votes

How should I interpret the impedance of an SMA connector?

The SMA connector by itself does not have an impedance of 50Ω, but it is specified to work properly in a 50Ω transmission line. A transmission line essentially is the arrangement of connectors and ...
Peter Rottengatter's user avatar
2 votes

How should I interpret the impedance of an SMA connector?

For cables and connectors, the 50 Ω impedance refers to the geometry of the connection. The idea is to maintain the same impedance all the way from source to destination. For simple coaxial elements, ...
Neil_UK's user avatar
  • 169k
2 votes

Generating Sinewave with PLL

my question is whether sinewave output is possible on an arbitrary PLL chip like the CD4046 or ADF4360. Some PLLs integrate the VCO, others don't. Especially RF PLLs tend to, and often the output of ...
Marcus Müller's user avatar
2 votes

RF ground capacitor broken off on Raspberry Pi 4 - How does it affect performance?

Traces crossing a slot or opening in ground plane, is a great way to create an antenna. It's likely these are small value capacitors (a few pF) to adjust the tuning of the slot antenna. It may still ...
Tim Williams's user avatar
  • 39.2k
2 votes

How to sample current in high-kHz to low-MHz

There are several important parameters you don't specify, but generally, this looks like exactly the sort of thing that wide-bandwidth current transformers are made for. Pearson (no affiliation) is, ...
Hearth's user avatar
  • 35.1k
2 votes

How can I slow down the rise and fall time of a power MOSFET without adding a delay before the switching begins?

No, you cannot. That's simply logically impossible: you want an N ms rise time. Because the rise can't start before you press the button (otherwise, your circuit would need clairvoyance) the rise can ...
Marcus Müller's user avatar
2 votes

Where to find/learn standard meaning of ω or φ, etc., in RF circuit design

The publications of the ARRL are a handy source of the information that you are looking for at a level you should be able to understand especially since you have a ham license. Start with the ARRL ...
Barry's user avatar
  • 16.1k
2 votes

Will this FM transmitter work?

I would at least suggest a high-frequency ferrite bead or resistor in series with the base if using an RF transistor. Using anything beyond MMBTH10 is overkill and inviting trouble, really. It's not ...
Tim Williams's user avatar
  • 39.2k
1 vote

Question About Utility Company Antenna Power/Radiation Concerns

That's not a lot of power, 2 W is half what a typical two-way portable radio would output. If the radiated power is 15 W that means that the antenna would have gain, roughly $$ Gain = 10\times log(15~...
GodJihyo's user avatar
  • 24.7k
1 vote

RF Microstrip trace polygon

Whatever you do, make sure you pay attention to the geometry of the stackup. If you put a plane above and a plane below, the transmission line changes from a microstrip to a stripline. Notice the ...
Voltage Spike's user avatar
  • 84.6k
1 vote
Accepted

RF Microstrip trace polygon

do I need to apply a ground polygon on the top layer side of the PCB or not? To make a microstrip transmission line, you do not. And if you do, you should keep the top layer ground region well away ...
The Photon's user avatar
  • 131k
1 vote

P2P communication: maximum range for low power & low bandwidth

You read about LoRa, so I'd guess you already stumbled upon the answer: faced with the problem that a low-power transmitter can't get data reliably across a channel of large distance, you reduce the ...
Marcus Müller's user avatar
1 vote
Accepted

Telecom Lines Conducted emissions noise travel

Presumably, no CM current in the Ethernet port means no ground current, and lifting it shouldn't make any difference. This is an unverified assumption, however. A current clamp on the ground ...
Tim Williams's user avatar
  • 39.2k
1 vote

What is inside of a typical RF transformer?

They make RF transformers that don't have a cover over them, so you could look at some of those. The covered ones will be the same sort of thing but with a bit of plastic or ceramic around them. There ...
GodJihyo's user avatar
  • 24.7k
1 vote

Transmitter parasitic drainage

Looking at the circuit board you can see that VDD goes through D1 and then to the pushbutton. But it also goes up to U1 and some other components, so most likely U1 is powered all the time and an ...
GodJihyo's user avatar
  • 24.7k
1 vote

S-parameters of a matching network

You need to distinguish between the use of your network, and what you might do in measurement, design and verification. In use, of course its output will be loaded in a nominal 200 Ω. If you want to ...
Neil_UK's user avatar
  • 169k
1 vote

Cranes operating on 433 MHz remotes experience shutdown

The vendor is perplexed by these actions. TL;DR: The vendor doesn't have the competence necessary to make those machines. You'll need a consultant electrical engineer who will do the vendor's job ...
Kuba hasn't forgotten Monica's user avatar
1 vote
Accepted

Why wouldn't one use a DAC for an RF transmitter?

Are you thinking that this isn't done? It certainly is. https://en.wikipedia.org/wiki/Direct_digital_synthesis A basic Direct Digital Synthesizer consists of a frequency reference (often a crystal ...
Ben Voigt's user avatar
  • 2,920
1 vote
Accepted

How can a Class E Power Amplifier be built and experimented with safely?

OP's circuit does generate voltage spikes at MOSfet drain that can considerably exceed the DC supply voltage. Switching current off quickly to an inductor is the cause. The circuit fragment of the few-...
glen_geek's user avatar
  • 26.6k
1 vote

Understanding impedance matching in RF PCB applications (STM32WB55)

Technically a shunt capacity of 0.6pF (or an equivalent, short 50 Ohm transmission line stub) would already be enough to make the output impedance 50 Ohm: The component values for the matching ...
Raonoke's user avatar
  • 626
1 vote

Coupling LNA and Band-Pass Filter Properly

Mini-Circuits provides S-parameters for both components which makes it easy to find out how both behave when cascaded. Between the amplifier and the bandpass filter I chose to insert a small ~2dB ...
Raonoke's user avatar
  • 626

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