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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Problem in communicating through NRf24L01 Module wıth Mega

I am running into this seemingly common problem one faces when using MEGA with the radio module. My experimental Settings are the following : MEGA 2560 as Receiver UNO R3 as Sender NRF24L01 radio ...
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30 views

Best way to wirelessly transmit data between two points over long distances [on hold]

So this is kind of a silly question, apologies in advance. Its for a tabletop game campaign, so "actual" realism is only partially required, but I like to be at least close to the real thing. I'm ...
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1answer
35 views

How to find/build a simple receiver for 12-15MHz radio frequency?

I am looking to buy or build a RF receiver sensitive to 12-15MHz. I can detect these frequencies with an expensive table-top radio spectrum analyzer for testing, but for operation need to have an ...
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28 views

PT2262 and PT2272 Lag

I have a pt2262 and a pt2272 rf link transmitter and receiver set. I notice that when I send signal from the transmitter to the receiver at a precise and regular interval, I notice that the receiver ...
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2answers
31 views

How to connect multiple rf433 transmitter to receiver?

I am doing a simple project where I place sensors at different parts of the house and send data to my rpi. I am using the rf433 for the wireless transmission but I discovered I cannot do multiple ...
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2answers
71 views

What Makes a Radio Transmitter Powerful?

I've been doing research on radio transmitters, and though I understand how the signal is generated and how data is transmitted, I still can't understand what defines a radio's transmitting power. How ...
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3answers
59 views

USB3 activity detection

Some USB hubs have status LED that shows activity. Let's say, I want to make a USB3 cable with status LED that would indicate any activity on the bus (changes of differential voltage). Is there a way ...
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1answer
33 views

Testing conductive RF shielding paint with a VOM

I heard it claimed that you cannot test the conductivity of conductive RF shielding paint with a Volt / Ohm meter. This was in reply to someone who had done so and claimed that the paint was ...
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37 views

GPS splitter with 200ohm DC load and 50ohm RF impedance on all ports

How can the GPS400 signal splitter provide a \$200~\Omega\$ DC load and \$50~\Omega\$ RF load to GPS receivers on all four ports? Most GPS receiver modules require an active antenna. As a result, ...
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61 views

Simple AM radio - how to modify it so it can work without ferrite rod antenna?

I am a beginner in electronics and I'm currently the most interested in RF-related topics. I did build simple AM receiver usind good old TA7642 and, after adding small 9V amp, the radio broadcast can ...
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24 views

RF transceiver with RSSI + direcional antenna [closed]

I'm looking for a RF pair or Wireless transceiver that has RSSI and also i searched the internet but i didn't find a suitable Directional Antenna, can you guide me in finding one ?? one of the ...
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34 views

How to read EMI absorber specs?

I am looking for some EMI absorber to shield a component from GSM 850/900 radiation. Never use one before. From p.2 for the datasheet below, the AB7050 absorber has ~-3.5dB reflection loss and ~80% ...
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2answers
35 views

How does the frequency information of RF signal is carried over optic converted output?

I have an RF input signal in the frequency range of 1000MHz to 2000MHz with the power level of 0dBm+/-1dBm throughout the band, this signal needs to be converted to optic signal using RF to optic ...
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57 views

When impedance matching networks aren't

As someone new to practical RF design (the theory is easy by comparison!), I have a relatively simple question when it comes to matching networks, and it has to do with best practices. Obviously, a ...
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45 views

RF/voltage clamp/limiter [closed]

I'm looking for a circuit that is called "RF clamp", "RF limiter", "voltage clamp" or "voltage limiter". The example of such circuit is a transistor Q on this picture: However, what I need is a ...
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1answer
22 views

can not comiunicate through ask rf module [closed]

I wanted to send data by ardunio through dra886tx(board on the left side ) and receive by another ardunio through dra887rx ; i don't know whats the problem but nothing happen on the receiver board ...
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52 views

How to avoid clipping of signal in case of rectification

When I use any of full wave rectifier, the signal level drops by the amount of n*Vf (0.7+0.7 ~ 1.4V in case of bridge rectifier and 0.7V in case of simple full wave rectifier) where n = no. of ...
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1answer
54 views

Question about RF layout seen in application note (Texas Instruments AN043)

I saw the following antenna layout in a Texas Instruments application note titled AN043, Small Size 2.4 GHz PCB Antenna. What is with the right angle the feed makes? Wouldn't that cause reflections? ...
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1answer
54 views

Balun Polarity Importance

Hello I am picking up a project from someone else who has a built a dipole that is connected to a 1:1 transformer with the intention of using it as a current balun. I have noticed that from documents ...
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1answer
43 views

Up/Downconverter issues

I am having some issues with my up and downconverter. What I'm trying to do is to receive a 125 kHz signal, upconvert it to 433.125 MHz, transmit it, receive that signal, and downconvert it back to ...
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2answers
33 views

How to calculate frequency and channel bandwidth

I made a regenerative receiver by slightly modifying the design at http://www.ke3ij.com/am-univ.htm to match the design below and with the right part combination I managed to pick up many stations ...
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1answer
33 views

RFC realization for bias of microwave transistor circuits

I saw the following configuration for the bias circuit of some microwave amplifier circuits. I think in the left figure the RFC is realized using a quarter wavelength short circuited stub (because of ...
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82 views

Best PCB antenna

I have to design a small PCB with a 868MHz PCB antenna. The board will be placed inside an metal casing, that has a small opening to allow radiation. I have previously successfully designed pcb ...
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1answer
92 views

Least overkill solution to transmit single bit wirelessly [closed]

I am looking for suggestions to transmit just a single bit wirelessly, through walls (limestone) and at a range of ~30-50ft. The purpose is a simple motion detector which produces a status bit and I ...
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50 views

Can WIFI PIFA Antenna pick up GSM signal over the air and radiate 900MHz harmonics?

My device supports 3G and WIFI (2.4 and 5G). The WIFI PIFA antenna is radiating 900MHz harmonics (1800 and 2700MHz) when cell modem is transmitting. After I removed the WIFI ant, noise disappeared. ...
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49 views

Books on Antenna Design [closed]

I'm looking for an Antenna design resource/textbook, because I want to prototype antennas with copper tape (2.4 GHz). I only know theory, but from what I can tell, antenna design seems to be very ...
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1answer
61 views

What is the most energy effecient type of RF oscillator?

Here are the options: the Gunn Diode, the Barkhausen-Kurz Tube(AKA "transmitting triode"), the so-called Lighthouse Tube, the cavity Magnetron, the reflex Klystron. I'm leaving out the Gyrotron ...
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1answer
80 views

Admittance inverter realisation in filter design

I read some theory about lowpass prototype filters in the "Handbook of Filter Synthesis" by Zverev and in "Microwave Filters for Communication Systems". I read these two because I want to understand ...
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2answers
65 views

Why isn't this VCO responding to my sawtooth waveform?

I'm learning how VCOs work, and I'm feeding it a sawtooth waveform to see the impact on my WiFi. This VCO outputs in a 2.4ghz spectrum, and to understand how it sweeps, I'm passing in a sawtooth ...
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1answer
40 views

RF Receiver Q/Q_N and I/I_N [closed]

What is the point of inverted Q and inverted I on a receiver? Specifically on FMCW radar applications?
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1answer
69 views

How can I direct an RFID reader to only read in a specific direction?

I'm trying to control the reading direction of an RFID reader, to only read in a specific direction. I made a drawing to exemplify my question. In the image you can see the setup I want to have. The ...
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2answers
58 views

RF Emissions Testing and Discovery of Hidden Undocumented RF Device

I would like to know is it possible to induce RF emissions (incidental waves (re-radiation) from a RF device that is not transmitting ? The purpose of this testing is discover whether there is a ...
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1answer
28 views

AC-coupled RF Microstrip routing over power plane

If I route a 433 MHz AC-coupled RF microstrip trace out of an MMIC such that it's referenced to a Power plane rather than a Ground plane, will that have a significant effect on the impedance of the ...
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3answers
80 views

Aluminum sheet as an underlay for electonic equipment

I am planning to build a NAS into a (sufficiently ventilated) closet. For flame protection and heat spreading, I mean to put a 2x700x550mm aluminum sheet under the equipment. Is this a good idea? ...
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51 views

HC05 Bluetooth Module - Certification - Commercial Usage

I'm interested to find out if this bluetooth module can be used in commercial products in Canada? Some of you will say "you can use whatever you want" but I'm not sure, because there's regulations ...
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1answer
36 views

Relation between EM frequency/Intensity and voltage/current in a Circuit

Let's say I have a circuit connected to an antenna which listens for a certain frequency range. The antenna would generate an electric current. For an electromagnetic wave we have two main properties- ...
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3answers
130 views

Can I put +33 dBm through an 0402 capacitor/inductor?

Consider the following capacitor here on Mouser (C1005C0G1H330J050BA). If my understanding is correct, the only power dissipated is due to the ESR - ideally, reactive elements dissipate no power (or ...
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2answers
59 views

High frequency rf resistors

I need non reactive resistors for use at LF thru HF (100KHz thru 30MHz) for use with radio receiving antennas as terminations. Carbon comp and carbon film work but have their shortcomings in stability ...
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1answer
59 views

one-way RF signal diode

Is there a special diode or band pass filter that will only allow RF signal to go though a wire in one direction like a diode does with electricity?
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1answer
39 views

VT pin flashing on RF circuit

The VT pin on the decoder side (signifying a valid transmission) flashes intermittently (sort of imitating a square wave pulse) This happens without me making any change in the circuit - no address ...
3
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1answer
45 views

Do LTE modules depend on specific carrier?

I am looking to buy LTE modules. So I searched in digikey. I found two similar parts: MOD HL VZW LTE 1.8V W/ ATT 3G MOD HL ATT LTE 1.8V W/ VZW 3G They are both the same except the description. ...
3
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1answer
74 views

RF microstrip track parameters calculation

I am currently finishing the design of a board where there are two antenna microstrip on the surface of the top layer. I have a 4 layer PCB. I use FR4,so I suppose dielectric is 4.6. Thickness of the ...
4
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1answer
106 views

capacitor RF performance

We have a standard SMD 0603 capacitor kit from that I picked a capacitor for use in a 868MHz Antenna matching circuit. I picked this 3.3pF capacitor from the kit. The Q is listed a 1MHz, but I read ...
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1answer
125 views

RF Transmitter and Receiver circuit controls

I'm trying to build a Radio controlled TX and RX circuit (using a 2.4 GHz chip and MCUs), to control a robot with four DC geared motors. I plan to use four momentary on-off-on switches on the TX ...
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1answer
60 views

designing trace anthtenas for 2 sets of rf rx+ tx

First of all forgive me for my mistakes, English is not my main language. I want to design a custom pcb (i'm not an expert just a hobby), I have a working breadboard circuit of an micro controller ...
3
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3answers
107 views

Frequency Synthesis from 1MHz to 800MHz

I've been trying to plan out a new project for a while. It's a wideband antenna anaylyzer for radio applications. I've figured out most of the details, but the most important part - the frequency ...
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1answer
107 views

Reflectometer - directional coupler

I tried to use a single directional coupler to create a reflectometer and was hoping to measure both amplitude and phase of reflected signal. My setup is a follows: The directional coupler is from ...
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29 views

Is it possible to induce RF Emissions from a RF enabled Device (part 2)

Would it be possible to take a device anything such as a wireless router or a wireless video and induce unintentional RF emissions while the power is being supplied to the RF enabled device (baseband ...
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1k views

Are there any open / unrestricted radio frequencies that are free for any use?

The only 'free radio frequency' that I could think of are the HAM radio bands. But they really aren't free, for they are regulated by laws that require you to hold a license, restrict what purpose you ...
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1answer
46 views

Measuring RF and heterodyned frequencies

I have a question about RF measurement techniques. The partial schematic above is the front end of an AM radio receiver kit. I have assembled the kit. The kit manual states, Transistor Q7 not only ...