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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24 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
116 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
52 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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40 views

What is an acceptable Bit Error Rate for Bluetooth Classic Audio? [on hold]

I'm trying to characterize a bluetooth classic system between a source and a sink. I have some data that suggests that the range before the audio gets 'choppy-but-not-bad' and 'choppy-and-...
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53 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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34 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 ...
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1answer
44 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. ...
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22 views

Use nrf24's to sense nearby peers

How can I use inexpensive nrf24 modules to simply detect the set of their peers that are in range? The design is for a festival, to see which of my friends are nearby and vice versa, as a personal ...
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1answer
61 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 ...
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1answer
103 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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111 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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48 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 ...
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3answers
100 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
100 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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27 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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3answers
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
39 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 ...
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1answer
32 views

Measuring RF voltage transformed by a toroid

This evening I attempted to measure the voltage off of a transformer used for detecting RF currents. This transformer was implemented as a single turn of conductor, through the center of a toroid ...
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1answer
28 views

Schottky diode equivalence in RF wattmeter?

I think I may have fried D1 in the circuit below, if that seems plausible? (During my initial testing, with up to 15W of input power, I had an open circuit after R4. I really don't understand how this ...
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2answers
121 views

What is a PA/LNA?

I saw a comparison of two similar radio receiver modules. They used the same IC, but one had a greater range due to the inclusion of a "PA/LNA" which I understand to be an abbreviation for "Power Amp /...
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1answer
43 views

What does means 'indiscriminate' in RF systems

The RWS-371 RF modules work as at the 434 MHz band, the documentations states: "These modules are indiscriminate and will receive a fair amount of noise".I guess they at least have some kind of ...
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1answer
58 views

Are the reflected and absorbed components of an antenna actually orthogonal? [closed]

I'm having a discrepancy between mathematics and my gut sense of reality. (Application: trying to figure out how much reflection I'm going to see in my package. I can tweak the CMOS, but I'm stuck ...
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1answer
50 views

how to implement a two-wire radar level transmitter? [closed]

I am developing a radar level measuring system. The radar transmitter is same as a Vega or Siemens impulse radar powered from a 4-20ma instrumentation loop. However, the sensor power requirement ...
6
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2answers
435 views

At what cable length does matching the impedance at the ends of the cable become important?

I'm building a base for a PMT that outputs pulses of width <=1 µs. In Hamamatsu's PMT handbook it states on pg. 112 (emphasis mine): When using a photomultiplier tube which is not a fast ...
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4answers
94 views

Do consumer high temperature RF ASICS exist at 200C?

So at lunch I was browsing Indiegogo projects and I saw this one here It's a wireless meat thermometer, I've seen it in some permutation or another a few times on sites like this. Apparently no one ...
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1answer
34 views

How to calculate the line impedance for WLAN antenna path and how to determine which kind of antenna is efficient for automotive product

I would like to know how to calculate RF antenna Line impedance, and makes the Pi filter values exactly in my Antenna path. I need a general guidelines and clear understanding of it. Please help me ...
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78 views

Can all RX and TX chips be made compatible with each other? [closed]

I have quite a few Radio Controlled Toys, Some I have hacked so that they become autonomous. This gave rise to a question: Can all Receiver (RX) and Transmitter (TX) chip be somehow made compatible ...
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46 views

Inductance values over the frequency

Does inductance vary over frequency in passive components. Consider a Coax cable for example, does the inductance value change as a function of frequency, lets say from 5GHz to 100GHz, does the ...
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32 views

RF Scheme for fast DAQ (accelerometers)

I am looking to design a data aquisition scheme for a field project where initially 5-10 3-axis accelerometers will be placed on a flexible object to gain information on the amplitude reference forces ...
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1answer
31 views

Baseband Processor

If a device can only be activated by way of RF then I would tend to believe that the BB processor (embedded via ASIC design) would need to be active and powered on yes ? If correct then does it have ...
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1answer
39 views

Dipole antenna RF Layout

I am designing RF layout on PCB, my PCB is in Circular form, In Pic 1, is my current layout in PCB, since this chip antenna is dipole in nature , so to form the dipole antenna there should be mirror ...
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41 views

WiFi obscuring 433mhz signal reception

I have a WiFi arduino device with a 5dbi omnidirectional antenna and a 433 mhz receiver board, based on Aurel AC-RX with a 17cm stranded copper wire Antenna both enclosed into the same box. This ...
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3answers
46 views

Is it possible to induce RF Emissions from a RF enabled Device

Would it be possible to take a device anything such as a wireless router or a wireless video and induce unintentional RF emissions while no power is supplied to the device ? Can you send it some range ...
0
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3answers
55 views

Linear Rise exponential fall pulse generator

For a neutrino detector related experiment, I need to design a circuit which generates the pulse similar to the detector. This is required to test the front end electronics. Here are my final goals: ...
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2answers
55 views

How does a device that is RF enabled power up the main CPU by way of RF?

Suppose you have a device such as a wireless video camera and the only way to power on the device is by way of RF. If the video camera has a CPU how can the baseband IC power up this CPU ? Is it ...
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0answers
23 views

How to determine the limit to the number of bluetooth masters in a given area?

I am working on concept development for a sensor network and considering scale-up issues. I have found plenty of info on the number of devices a bluetooth master can connect to and I have found a few ...
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37 views

External whip 868MHz Antenna via coaxial cable. Ground Issues

I have a RF module that works at 868MHz.It works as transmitter and as receiver. (lambda:0.345m lambda/4=8.64cm). The RF module ground plane (GND_PCB) is 10x10cm, so bigger than lambda/4. By default, ...
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27 views

How do I design an antenna in desired frequency with preset equivalent circuit model?

I am working on a project that an oscillator drives 1 mH inductor in 7.5 KHz. This oscillator also happens to be very efficient. However, I am constrained with inductor value. So, to make my design ...
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1answer
33 views

How did four-course LF radio navigation ranges have their beams other than at 90° / 180° angles?

The four-course Low Frequency Radio Range system used for aircraft navigation (in the US and elsewhere) in the 1930s and 1940s used a pair of directional antenna (with figure-of-8 shaped radiation ...
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3answers
119 views

What do I need in order to make my arduino to transmit / recieve signals exactly at 433.68 MHZ?

Before I start, please note I am not even near to be an expert in electronics - I just try to do my best with what I have - I apologize in advance if my language is not technical enough. I have a ...
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1answer
61 views

How does an RF transistor bias work?

In many RF applications I have seen transistor circuit that looks something like this: simulate this circuit – Schematic created using CircuitLab Now, I understand the role of all the ...
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2answers
89 views

What is the output impedance of HF power amplifiers?

In case it matters, let's discuss solid-state, linear, class AB amplifiers operating below 50 MHz and on the order of 100 W. Here's my confusion: I'd think ideally, the output impedance of the ...
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1answer
44 views

Minimum threshold fm equation

I have been searching and working to understanding this equation below in relation to FM signals minimum threshold. Pr [dBm]= (Eb/N0)+10∗log10(Rb)+N0 −Gm Eb is the energy per bit to noise power ...
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98 views

Interface of HC05 Bluetooth module and RF 433Mhz Module

I am trying to make an Android controlled toy car. Now the range of the bluetooth module is around 10 meters. However, to increase the range, I decided to interface the RF module with the Bluetooth (...
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2answers
68 views

Good faraday cage to block bluetooth beacons

For a project I need to test often with bluetooth beacons linked to an iOS app. When I'm at home (office at home) I like to reduce exposure to radiation as much as I can. Not in a obsessive way, but ...
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1answer
87 views

How to find the resonant frequency of a human body?

I've read that the human body has resonant frequencies somewhere around 50MHz. I also think it would be interesting to look for values in other ranges like 10-100 kHz. I'm wondering how to build a ...
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42 views

Boost a HV power supply from +1250 V to +1500 V

I'm designing a base for a photomultiplier tube using a recycled HV power supply. The power supply is an EMCO C12. The base has a 14 pin socket (to connect to the PMT), the EMCO C12, a DAC to program ...
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41 views

Initial permeability of toroids in ATX power supply?

I'm interested in re-using output side or possibly the line filter toroids from a junk ATX switching supply. All turns are removed, just the core. I think these are powdered iron cores and any guess ...