Short for Radio-Frequency. Frequencies at which radiation (intentional or not) plays a role. Typically associated with wireless communications, but also relevant for high-speed PCB design.
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votes
1answer
121 views
Can enough RF power melt an antenna?
I've heard of someone getting RF burns by touching a high power antenna. If enough power is supplied to the antenna could it melt, or would anything else happen? If so, how much power would have to be ...
2
votes
0answers
41 views
Wireless water level sensor, in sump. Installation best-practices for longivity
My wireless water-level sensor is working fine, and when deployed in the sump-well, it is giving me periodic readings quite well. At this stage, I have the circuit still on a breadboard, and now plan ...
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votes
0answers
46 views
How to connect a CAN transceiver to a microcontroller and then to an RF module? [closed]
I'm doing an RF interface between a computer and a CAN bus network. I'm using a CAN transceiver, a microcontroller (ATmega32C1 Automotive) with CAN protocol, and an RF module.
I'm stuck at the ...
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votes
2answers
64 views
What is the range of a 2dB usb wifi dongle? [closed]
For a home robotics project I need to connect my laptop to my robot's Raspberry Pi using wifi. For this to work I want to buy a simple usb wifi adapter to plug into my Raspi. I will need a range of ...
-7
votes
1answer
90 views
Creating custom frequency [closed]
I am working on building a 134 khz transmitter with range of 3 miles. I'm foggy on the calculation for capacitor vx resistance and transistors that will create this frequency. Any help would be ...
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vote
2answers
65 views
Source of electromagnetic signal in kHz regime
I was wondering what emits electromagnetic signals in the kHz regime? When I touch the inner pin of an BNC cable connected to an oscilloscope, I see a large sinusoidal signal with ca 40 kHz.
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0answers
52 views
RF Link with APC220 between two PIC16F877's
I am attempting to communicate through a RF link between two PIC16F877's using APC220 Radio Transients. When the PIC UART's are connected with wires between TX and RX they communicate just fine, but ...
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votes
0answers
50 views
RF reciver design thoughts [closed]
I'm planning to design a reciver circuit that will handle all of my 434Mhz transmitters but I don't have any idea about how many transmitter this reciver will handle at same time in terms of coverage ...
0
votes
1answer
27 views
antenna multicoupling connecting lines
I'm trying to find information about how to properly calculate the connecting coax length in a string of cavity filters for a VHF multicoupler. I figure it should be something like a 1/4 wave length ...
2
votes
4answers
130 views
Troubleshoot Crystal Radio
Alright, I'm totally confused. I have built the following circuit with absolutely no result, not even a click. Even after reading through several other similar questions on the board, I haven't ...
3
votes
3answers
100 views
Radio wave transmission and receiving antenna
When you transmit signals at radio frequency why are the antennas open ended (open circuit)? I can understand that changing the electric field causes changes in the magnetic field and hence the wave ...
0
votes
1answer
68 views
What determines how narrow a radio channel can be?
As an example: We used to have analog TV broadcast but now we're switched to digital. With digital we're able to pack in more data into a smaller frequency range. I assume that it is our advancements ...
5
votes
4answers
139 views
How do arcs generate radio-frequency
When I have an electric arc, and put an AM radio nearby, I hear a crackle and the station that I previously heard goes away. I am wondering what is going on with the electricity through the air to ...
2
votes
2answers
103 views
Coaxial cable theory
Well I was learning transmission but I got a bit confused when I came to coaxial cables transmission at radio frequency.
What I am lost is how the waves are propagating in the cable, I was thinking ...
0
votes
2answers
63 views
OOC coding in Wireless Radio Mesh Network
Can anyone explain me whether OOC (i.e. optical orthogonal coding) works in radio frequency? Or only for optical/laser technology?
3
votes
5answers
123 views
Are E and B fields in phase in electromagnetic radiation?
I recently wrote this answer, in which I said:
Radio waves are electromagnetic radiation. Electromagnetic radiation contains of two components, one electrical and one magnetic. These components ...
5
votes
5answers
153 views
What is the difference between electromagnetism and electromagnetic radiation?
In a previous question, I asked if having 2 coils of wire with electricity flowing from one to the other is RF, and they replied that it was not Radio Frequency. I was puzzled because I thought this ...
1
vote
2answers
135 views
Simple Morse code transceiver circuit
I want to build a portable device (handheld) that receives and transmits Morse code in the form of Radio Frequency. I want the antenna length to be 8 inches or less and would also like a range of up ...
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votes
0answers
88 views
Simple Morse code walkie talkie circuit [duplicate]
I want to learn more about RF and start by building 2 simple morse code transceivers. I don't care what the frequency is. I want the distance to be a half a mile. Is there a simple circuit without ...
1
vote
1answer
50 views
ZigBee module compatibility
Are the XBee series 2 modules from Digi compatible with other brands complying with the ZigBee standard?
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votes
2answers
81 views
Can the antenna of a Wi-Fi modem pick up a cell phone's MIN or ESN?
Specifically: Can the antenna of a Wi-Fi modem pick up a cell phone's broadcast of its mobile identification number (MIN) and electronic serial number (ESN)?
Generally: We are trying to determine ...
-1
votes
0answers
49 views
“listening in” on a sensor's RF communication to a display
I would like to use a standalone underwater depth finder, the RF45 from Humminbird. This device typically communicates its data wirelessly at 916.5MHz to a display watch.
I'd like to use the ...
3
votes
1answer
140 views
Is sending a signal over 433.92 Mhz blocked by plastic?
to be honoust: I never understood radiowaves; how I can receive radio in my house? Transferring a complete video through air from laptop to router? Never a clue.
So with that (lack of) knowledge my ...
3
votes
3answers
161 views
RF Design: A Bluetooth Repeater
I am currently stumped in the design process in creating a method to intercept Bluetooth signals with an antenna and simply outputting the exact signal through another antenna.
Some Background
I ...
10
votes
1answer
193 views
GPS Design Review (RF Input)
I've designed a PCB in Eagle to host a GPS Receiver module and a GPS patch antenna. The RF input to the module is specified as a 50Ω unbalanced (coaxial) RF input. I used this calculator to calculate ...
2
votes
4answers
139 views
Measuring Signal Strength with a RF Circuit
Note: I'm primarly a 4th year Computer Science student, but I have also interest in electronics but I have very limited knowlege.
Is it possible to measure the signal quality or level of a RF ...
1
vote
4answers
129 views
Radio Waves reach in function of frequency
What is the relationship between the reach of a RF signal and its frequency?
What I mean is: If power is kept constant, should I use high or low frequency waves to get a better reach? Why?
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vote
2answers
81 views
Dipole antenna length calculation — why so much variation?
Was checking few online calculators for dipole antenna length computation, and found that each tool, gave a different length. Is dipole construction based purely on heuristics, or is there some sound ...
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vote
3answers
127 views
Stereo AM/FM Concept?
There are tons of schematics and concepts online of AM or FM transmitters. I wish to build one using discrete components (at most an op-amp).
The problem is, how would transmission of stereo work? In ...
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vote
0answers
69 views
Why does my bluetooth dongle use more current when paired then when idle?
I have a bluetooth dongle which is connected through USB to my PC. I wanted to measure the current drawn and hence I connected an ammeter in series with the 5V line and am measuring the current. I ...
