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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2
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1answer
13 views

433MHz RF transmission only working when holding usb cable in the air

I'm really puzzled about this. I have a simple transmission between two ATTiny85's going on with a 433MHz receiver and transmitter. The transmitter is in the basement so the signal is rather weak but ...
0
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0answers
10 views

VirtualWire and ServoTimer2 on an Arduino Mega

I faced some problem in using VirtualWire and ServoTimer2 on a same Arduino Board. The RF module on the board work well, but the servo did not execute its operation as stated. Anyone had solution on ...
2
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0answers
63 views

how does a cell phone transmitter work?

I came across a question that is really puzzeling me. I did some basic calculation for a cell phone transmitter. I based on 900Mhz band and assumed a 20Km distance to a cell tower. On top of that I ...
9
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2answers
533 views

How much power do I need to transmit a radio signal through a solid ice crust 100 km thick?

Imagine I put a floating probe inside the subglacial ocean of Encelado or Europa: how much power should my radio have to be able to communicate from external surface with the probe? Or, in different ...
0
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1answer
48 views

Weather radio antenna [closed]

I am trying to build a simple weather band receiver. I bought a breakout board and im trying to find an antenna. I ripped apart a weather radio that looked to have a (rubber ducky antenna) and found ...
-1
votes
1answer
39 views

What is the difference between Rf Gain Blocks & IF Gain Blocks?

As advertised on websites of large manufacturers like Analog Devices And Texas Instruments I am aware of the difference between an IF stage and an RF stage, however, I was curious if there was any ...
0
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1answer
29 views

Radio Control DC Motor With Potentiometer

I am looking to control a 12V 16A 180RPM DC motor. The package I am purchasing includes this motor, and a speed controller. Please see this link for the exact detils. The speed controller comes with ...
0
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0answers
26 views

How can I use remote controller with an RF module?

I'm using an RF module for transmitting and receving remote controller data like an AV sender. And I have to add preamble, start and stop bit, but I can't use the UART because all remote controllers ...
6
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2answers
243 views

Using copper clad for RF projects

As a novice reading "Build Your Own Transistor Radios" by Ronald Quan I was kind of mystified by the author's statement that using "vector" board would be easier than using prototype boards, but the ...
1
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3answers
57 views

Inductor specifications for AM circuits

I am working with the book "Build Your Own Transistor Radios" by Ronald Quan in which he has a lot of AM projects. I am having a hard time figuring out what I need to buy from his specifications. For ...
3
votes
1answer
89 views

RF Circuit (what does capacitor do?)

I'm trying to work out why a 0.7pF capacitor was chosen. The circuit operates at 12GHz. At 12GHz, the capacitor has an impedance of about \$18\Omega\$. Also at 12GHz, ...
0
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1answer
34 views

RF Ground (Reflections?)

I'm trying to understand how someone can ground an RF signal (especially relating to microstrip lines). I think I'm missing something... Since the impedance of ground is supposed to be \$0\Omega\$, ...
3
votes
3answers
71 views

Consensus on microstrip trace impedance calculations?

I'm designing a PCB that has a 2.4GHz signal that I'm routing to an SMA jack. I'm trying to figure out the geometry of the necessary microstrip trace. This is the first rf PCB I've worked on. The ...
1
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1answer
53 views

RF transmitter connected directly to sensor

I am trying to implement the following : I got 2 (more than 1 anyway) distinct sensors and an arduino and I need to get the sensors' state wirelessly. Here is what I have thought of so far: As for ...
1
vote
1answer
57 views

Trouble with phase locked loop: phase comparator is just showing the VCO output (with picture)

I am using the CD4046BC for the first time, and do not understand something that is happening. I am using the type I phase comparator, which is just a simple XOR logic gate. When I have the input as a ...
0
votes
1answer
88 views

Power LED's using RF transmitter and receiver with Arduino

I'm working on a project that I have two sensors, two Arduinos (a YUN and an UNO), two LED's, and an RF transmitter/receiver It's a pretty simple procedure: Activate a force sensor, send it via RF ...
0
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0answers
20 views

Minimum Distance for Corner Reflector

In RF-Measurements Trihedral corner refelctors are often used as calibration targets because of their constant and analytically defined radar cross section. The RCS of a trihedral corner reflector ...
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0answers
39 views

Crystal oscillator output impedance

I want to build a varactor frequency tripler (from 80 to 240 MHz). Can't find XO output impedance for an input matching network. I would appreciate any advice on this matter.
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1answer
59 views

Appropriate electronics to use for scoring closest Nerf football air cannon shots? [closed]

Appropriate electronics and sensor technology to use for scoring closest Nerf football air cannon shots? The general concept would be to have a target area marked on the ground around a target device ...
0
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0answers
84 views

RF amplifier, why cascade two amp doesn't work?

I am currently working on a amplifier circuit on 8Mhz signal (around -40dbm). The amplifier is based on a IC chip (lm7171 bin). The problem is, the amplifier works perfectly for individually ...
3
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2answers
115 views

RF Narrow bandpass filter (crystal ladder)

I am currently designing a narrow band pass filter at around 8Mhz, using the crystals having a resonance frequency of 8Mhz. Using the tutorial from ...
0
votes
1answer
86 views

Shorted antenna DC-blocking capacitor value

I have an antenna that contains a DC short to ground ( a PIFA antenna at 1575 MHz in this case ). However, my device cannot tolerate a DC short to ground, so I need to include a blocking capacitor in ...
0
votes
0answers
58 views

Reason for choosing particular frequencies for ISM bands

There is a number of ISM bands, including the widely used 2.4 GHz. But which were the reasons for the FCC and ITU to pick those bands? I suppose, that with 2.4 GHz there's a connection with water ...
2
votes
2answers
51 views

Can I safely operate a PLL below it's “minimum” RF frequency?

I was wondering if anyone has had luck operating a PLL below the spec'd minimum RF frequency. For example, Analog's ADF4107 PLL specs 1-7GHz RF input frequency, but I don't immediately see why it can ...
0
votes
1answer
91 views

Reducing voltage using a resistor

I want to know how to reduce an AC voltage of 175 V to 110 V using a resistor. The device I am using is 200 Watts, 110 V but the voltage from the source is 175 V. What value of resistor should I use ...
1
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1answer
106 views

Arduino + XBox 360 RF module [closed]

Recently I tried making an XBOX controller adapter for my PC as per these instructions. As I have very little electrical knowledge, immediately I ran into problems. Connected everything as shown and ...
2
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1answer
41 views

Powercast Powerharvester Chipset PCC110 Issues

I recently picked up a PCC110 datasheet, an RF energy harvester. I assumed the 3 pins would correspond to GND, Antenna, and Vout (the datasheet does not specify). I attempted all of the permutations ...
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3answers
142 views

Video stream over RF

I want to stream video from a camera 640x480 frame of 8-bit approximately. I don't want to use wi-fi. I capture the data, encode it, transmit the signal over RF and receive it. Decode the signal. My ...
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votes
2answers
84 views

Is there such a thing as a wireless solid state relay

I want to control multiple baseboard heaters in my house, but I don't want to put a raspberry pi connected to a solid state relay behind each baseboard heater, or even connect it to the thermostat, as ...
3
votes
3answers
118 views

Xbee Transmitting garbage characters

We tried to make two Xbees communicate with each other. One Xbee module(configured as transmitter) is connected to one PC (PC1), and the other Xbee module(configured as receiver) is connected to ...
6
votes
0answers
118 views

Does putting a car remote on your chin make it more effective? [duplicate]

Recently asked on Physics.SE: Why does a remote car key work when held to your head/body? And also, similar claims abound. RF engineers know that putting a big conductive thing like a human head ...
3
votes
2answers
608 views

Will RF cause any health problem? [duplicate]

This is out of curiosity. I am working with rf 433 MHZ transmitter receiver module. I just wanted to ask whether it affects health in any way. I have read that such radiation has carcinogenitic ...
2
votes
1answer
54 views

What are class E amplifier RF choke guidelines?

I am designing a novel circuit that I beleive has not been constructed yet! No -- I'm just using an exotic switching device for a class E amplifier. My operating frequency is close to the 160 ham ...
1
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1answer
72 views

What is the modulation technique used?

I own a Tx/Rx Radio Direction-Finding (RDF) set for a sport called falconry, basically, locating & recovering a pet falcon after flight. The Tx tag is at 218.025MHz from Marshall Radio Telemetry ...
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0answers
46 views

Frequency modulation occurs not in an expected way

I've built this oscillator. Then I gave it a DC bias and connected an mp3 player. Result: I have local fm-stations muted at 90MHz, 90.75MHz and 89.25MHz. However, at 90MHz an mp3 music is very ...
0
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4answers
102 views

Simple broadband RF generator [closed]

How to make a generator of RF signal which have multiple signal outputs ? Details: ...
1
vote
1answer
46 views

Calculating Signal Loss (dB) Through Vias

Does anyone have any useful calculations or links to material covering good ways to calculate signal loss through vias? What would be perfect is a graph with typical loss in dB over the range 1GHz ...
4
votes
1answer
65 views

Replace SMA Connectors with Direct Connection

I am combining the layout for two PCBs, one with an RF output SMA jack, and the other with an input jack, into a single PCB. We were originally connecting the separate boards with a ~3" segment of ...
1
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1answer
42 views

Routing traces for GPS antenna input

I'm trying to integrate a breakout board circuit from SparkFun into my own design. It uses an external coax antenna with a SMA connector. I've brought their circuit over in its entirety, and from a ...
0
votes
1answer
69 views

RF proximity sensor around a perimeter

I'm trying to build a proximity sensor that triggers on nearness of the sensor to a perimeter antenna, sort of like an underground invisible fence. I want to feed that input into a microcontroller ...
2
votes
1answer
47 views

Connecting two RF devices

I plan to build two RF modules. One is an analog down converter with a balanced output IF of ~50 MHz The second in a fast ADC @ 100 MSPS with balanced input. I want to have them separated for ...
2
votes
1answer
120 views

Why are 2.4 GHz amplifiers costly while RF amplifier IC's are cheap? [closed]

A lot of 2.4 GHz amplifiers on eBay are sold for $30-50, but the amplifying chips are available on Digikey < $1. Why? The PCB's are two layers and other SMD components are quite cheap too, then why ...
2
votes
2answers
88 views

How solder inductance affects RF circuits?

I'm assembling a VHF oscillator (90 MHz) and plan to reach UHF and SHF some day. Should I worry about solder inductance affecting an oscillator performance? If no, then when should I take it into ...
1
vote
1answer
58 views

Will software-based DSSS work?

We are implementing a 2.4 GHz RF link using a TI CC2541 chip (http://www.ti.com/product/cc2541) and we are new to RF design. We want a robust, low-bandwidth, low-latency link. We were thinking of ...
2
votes
4answers
164 views

building simple radio

I'd like to build a simple AM radio (so simple it will only receive a single AM channel). What is the simplest way to build a single channel AM radio that will output to an 8ohm speaker? (e.g. 1030 ...
1
vote
1answer
53 views

What are important inductor parameters to specify for use in a matching circuit?

The title could be more clear: I have a matching circuit but the datasheet is restricted. I'll post a reference matching network as a schematic here. simulate this circuit – Schematic ...
1
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4answers
199 views

Are wireless links symmetrical in practice?

From the top of my knowledge in the theory of EM propagation, two antennas show the same gain if used to transmit from A to B or ...
3
votes
2answers
55 views

How can I deal with interference from a test RF signal (XM radio) in order to get a live RF signal of the same type?

I'm located at a manufacturing plant where they have a test XM radio signal. I have a software engineering department located at the same plant that needs to work with a live XM signal. The plant's ...
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2answers
178 views

Arduino-Arduino RF Communication, key needs to be pressed several times

I'm communicating two Arduino i.e. Arduio UNO as sender & Arduino Mega as receiver via RF-433 MHz transiver module. Communication is sort of working but there is one problem. If I want to send a ...
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0answers
73 views

ground plane on 2 layer board with wifi module

I have a 2 layers PCB that I mount a Wi-Fi module. Components (SMD) are placed on the bottom layer and the Wi-Fi module is on the top layer. I apply ground plane on both layers, as I read, it is ...