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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44 views

RF Energy Harvesting Project

I am presently working on an energy harvesting system using RF signals. I have read some of the other posts made on this topic and have learnt quite a few things. However, I have some questions that I ...
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5answers
463 views

Very high speed counter (around 1.5 GHz to 2 GHz)

I am thinking of a device that can measure the distance of an object from a sensor using a radio transmitter and receiver pair. I'm thinking of using a counter at the sensor side, with a ...
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0answers
59 views

What kind of antenna is this?

The product page for this antenna supplies meager information. Do any of you RF gurus have a guess what kind of antenna this is as well as any other insight or reference radiation patterns?
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2answers
76 views

Headphone cable as antenna

How can headphone cables act as Antennas for built-in radios in smartphones ? Is it possible because of different frequency channels or what is the theory/mathematics behind this? On a side note, ...
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2answers
47 views

CC1120 and RF output pin and network

I am working on a hobby design and thinking of using the CC1120 for my RF transceiver. One thing that has me confused, however, is the matching circuitry on the RF input and output of the CC1120. ...
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0answers
65 views

Modifying AM radio to receive CB/CW/HF 27Mhz signal [closed]

I'm working on a project that calls for pre-used radios to be modified to detect an AM CB radio broadcast. I've never done any work with radios before, and have been trying to hunt down any sort of ...
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1answer
50 views

Calculating the “ball-park” range of a transmitter including dBi

I'm looking to buy a tranceiver that has a LOS range over 100m at minimum 1kbps. (preferred 28kbps). I've been looking at this device I'm using this calculator and I'm getting over 180 miles which ...
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1answer
19 views

Multi-antenna extension for NFC

Like many, I am new to this. I am working on a project that would require a short read range over a covered space, like a person's body or table top. Could I make an extended antenna from my smart ...
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1answer
51 views

How does Altium Designer's “impedance constraint” feature work?

Altium has a design rules option for setting a track width constraint according to line's impedance (e.g.; 50\$\Omega\$). How do I use it? Please give me instructions or a link to an online tutorial. ...
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3answers
32 views

Using Bluetooth 4.0/LE verses RF

I am asking this question in hopes to get a solid answer from anyone who has direct experience dealing with the most recent RF as well as Bluetooth 4.0/LE developments. What I am essentially trying ...
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3answers
116 views

RF transmitter circuit explanation

I just can't get my head around how these RF transmitters work: simulate this circuit – Schematic created using CircuitLab What I do know about them is the following, correct me if I am ...
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3answers
118 views

loop area and EMI

I always hear something like "reduce the loop area" when reading materials on EMI reduction. Why we need to minimize the loop area? I have two guesses: Smaller loop area will influence less signal ...
3
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0answers
95 views

How to avoid regulatory approval regulations, when chosing a RF module?

I've been trying to implement RF capabilities into my projecto, but I don't want to pay thousands of euros to get an ETSI certification in case it gets into production. I know that if I get a complete ...
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1answer
17 views

Displacement current generation in dielectric and in vacuum? How is it different?

I understand how the displacement current work in dielectric such as in parallel plate capacitors but don't know how they would work in a vacuum where there is no dielectric present. Can someone ...
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1answer
48 views

Improving reception of 318MHZ remote control

We have a gate opener with keyfob-type RF remote transmitters that operate at 318MHZ. The range from inside the car is about 75 feet -- less than we'd like due to the time taken by the gate ...
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2answers
52 views

How to protect a RF chip from thunderstorm static electricity?

I'm working on a open-hardware wireless wind sensor. It's designed for being installed on mountains, where thunderstorm are quite often. I use a Si4461 RF chip, with a half wave whip antenna. My ...
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0answers
53 views

Getting the best range with XBee-Pro 900 XSC S3B

I have a pair of 900 XSC S3B xbee pros and a couple 2dBi duck antennas. I just did a simple outdoor range testing and only got about 2,000 feet. I was outdoors without any buildings in the way, but ...
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2answers
57 views

Perform digital modulations (HW or SW)

I am considering doing a project which revolves around microcontrollers (AVR, or arduino) and digital modulation to learn about digital RF. I have simple things in mind, just for experimentation. ...
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66 views

saw resonator based low power RF transmitter

I am basically trying to design a RF transmitter and receiver using the saw resonator. the values I am using for the circuit are: C1= 5pF, C2= 18pf ,L1= 33nH, RF bypass (Ceramic cap) = 470pf, R1= ...
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1answer
101 views

What is the difference between peak-power, average power and true RMS power in RF measurement?

What difference between peak-power, average power and true RMS power in RF measurement? I have read a peak-power measurement can calculate average power measurement also. Does any of these needs ...
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2answers
84 views

What power is measured by a spectrum analyzer?

Is the signal level that is shown in a spectrum analyzer power of the signal being measured. If yes then what power is it: average power, true power or peak power? Also when using a power meter for ...
3
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2answers
55 views

RF Wakeup - Battling power consumption

I am currently using two nRF24L01+ (2.4 GHz RF transceivers) together with two AVRs to create a keyless entry system. My problem is battery lifetime when using a CR2032 battery to power the key. The ...
2
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1answer
99 views

Choosing capacitors for Microwave RF application

I've recently been given a project to lay out some PCBs which will contain a few Mini-Circuits RF amplifiers, and their associated biasing components. However, since I need to have several stages of ...
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1answer
14 views

Need some RF help - integrating with a Xemics DP1203 transceiver

So there are some devices (timing photogates) that use these chips (DP1203C915) to send data out over RF at 915MHz to a box that performs timing and split-time calculations. I would like to be able ...
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4answers
307 views

Non linear device with two frequencies

I got this on an interview question and I still don't know the answer. What output will have a nonlinear device if we will give two random frequencies \$f_1\$ and \$f_2\$? I answered that it ...
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3answers
90 views

Wireless EEG electrode design

Currently, all 'wireless' EEG systems acquire signals from electrodes which are wired to an amplifier, a filter, a digitizer and then finally a wireless module. I want to design a system that's ...
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1answer
477 views

Does amplitude of FM signal even matter?

Thinking about FM modulated signals that store information only in frequency so that their amplitude has no effect on the sound, I began to wonder: Does the amplitude even matter in the end? Well, ...
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1answer
36 views

Bandpass Filter Balanced Ports?

I have a question regarding bandpass filter. What is unbalanced port and balanced ports? I noticed that outputs of balanced ports are connected to RF_P / RF_N of Zigbee IC. What are RF_P / RF_N?
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1answer
76 views

What signal will come in?

I have a simple setup as shown, I would like to know what kind of RF signal will come in? Since the filter is configured around 2.4GHz, will all ISM (WiFi, Bluetooth, Zigbee, etc.) come in? The ...
4
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2answers
418 views

Robot following you; what's the best way?

I built a human-sized robot that can follow anyone wearing an IR beacon. It works quite well indoors and it's quite precise, but outdoors it is completely blind due to sunlight infrared. I have a ...
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0answers
32 views

Push-on coaxial connector with RF leakage performance comparable to threaded-coax connector?

In examining the performance characteristics of the push-on SMP connector I've noticed that the RF leakage is at best -80dB @ 3 GHz and then continues to degrade as the frequency increases to -65 dB ...
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3answers
151 views

900 MHz vs 433 MHz for urban environments

At ranges of a few hundred meters, will there be an appreciable difference in performance (ie range, bit rate) between 900 MHz and 433 MHz for digital applications in an urban environment? Forgot to ...
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2answers
51 views

How does Signal-Noise-Ratio related to receiver power

If I have the instaneous Signal-Noise-Ratio (of the receiver), but no other information, and I am interested in the instaneous \$\mathbf{Power_{received}}\$, is there any relationship between these ...
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1answer
88 views

PC to Arduino wireless link (low latency)

I want to build a robot car with an camera gimbal on top of it. This robot and gimbal should be controlled wireless by a gamepad and the head tracking of an Oculus Rift. As it is with the Oculus Rift, ...
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0answers
49 views

How to calculate Input backoff per carrier of a satellite

I was trying to calculate the sizing of SSPA in my satcom network where input backoff per carrier is required to calculate Power flux density. My current network configuration in C band is Total ...
7
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1answer
174 views

What does sequences like 1-3, 1-10, 1-3-10 etc in a spectrum analyzer mean?

I have read in a paper explaining spectrum analyzer basic 'When selecting the RBW(resolution BW), there is usually a 1-10 or a 1-3-10 sequence of RBWs available. More RBWs are better because this ...
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1answer
84 views

Does there exist a digital wireless broadcast protocol?

EDIT: Thanks very much to @pjc50, @dave-tweed, and @MoJo For their valuable comments. I apologize for the ambiguity of the original question. I've made edits below to clarify. I am in search of a ...
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0answers
61 views

Communicate from Arduino to mobile phone using RF

I am looking to send an alert signal from an Arduino to a mobile phone (GSM, preferably Android) The signal by itself is quite small, hence high transmission rates are not a priority. The preferred ...
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0answers
77 views

Electromagnetic field voltage induction

I need help regarding voltage induced in load (cables). Say we have a 10 V/m radio field at 250MHz carrier. It induces 1V to an impedance of 50 Ohm (x length). If the cable impedance is increased to ...
6
votes
1answer
128 views

A poor man's alternative to a network analizer for antenna matching

I'm doing a small board with a 915 MHz transceiver. A small helical antenna is used, which is located on board with a very short path (10 mm) from the IC, including balun and a matching network. There ...
18
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4answers
524 views

At what frequencies does PCB design get tricky?

I have designed many mixed-signal PCB's where the highest-frequency component is the microcontroller's crystal oscillator itself. I understand the standard best practices: short traces, ground ...
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1answer
86 views

How to add automatic frequency control to varicap voltage?

I've built a TV tuner radio using a tuner with voltage synthesis tuning and a CD2003 FM demodulator. A similar schematic can be found here. The reception quality is very good, but it is difficult to ...
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1answer
61 views

Netduino and RF, on the cheap?

Hardware support for the Arduino is vast, much have already been done and a lot of devices has been tested. Netduino, not so much... But I want to add a RF receiver to my Netduino, so it wirelessly ...
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0answers
84 views

Interpreting Data Sheets (“Typical Applications”)

I've recently been researching various transceivers, but I run into trouble as soon as I get to the "typical applications" section of the data sheet. With the Si4464 for instance, the example ...
3
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1answer
109 views

Antenna matching network. What? Why? How?

I'm designing a small board featuring a transmitter in the 900 MHz band. Since RF is definitely not my strongest subject, I'm basically trying to follow all the datasheet recomendations regarding ...
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2answers
77 views

Is it possible to detect cellphone IDs in an enclosed area

I'm working on a project where I need to be able to identify different cellphones in an area. Ideally I need a way to identify when specific cellphones enter and exit a range - this could be IMEI or ...
6
votes
2answers
196 views

How does this quartz antenna work?

I picked up something called a quartz antenna at a surplus store for $2.75 so I could tear it apart. This is what I found: There were two small cardboard boxes filled with loose quartz crystals ...
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1answer
83 views

How do I sniff this RF Transmitter Gate Opener Circuit?

What piece of hardware am I looking for to observe the transmitted radio signal? Would an oscilloscope come in handy here? is this a 2-channel RF remote, a 3channel RF remote, or something else? My ...
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4answers
89 views

How do multiple transmitters and single reciever work?

I have multiple digital transmitters sending packets to an receiver, and packets from different transmitters may arrive at the same time, how can the receiver differentiate multiple packets at the ...
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3answers
90 views

NPN transistor to short RF remote switch button

simulate this circuit – Schematic created using CircuitLab Hi, I am trying to replace RF remote switches with transistors and want to control them using raspberry pi GPIO pins. Here as ...