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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40 views

designing oscillator in range of 80-120 Mhz using bc547 instead of jfet? [on hold]

Can i design oscillator in this picture with using bc547, if yes, how i can do. .by the way in multism the oscillator in picture doesnt have output frequency in Mhz range.but cource lecturer did it!. ...
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33 views

Antenna to reject 5.8Ghz Interference

I live a couple miles past where "normal" high-speed internet is available, and for years I have used a radio WAN link on a 70' radio tower to connect to my ISP in town, 4.65 miles away. I have a ...
0
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0answers
18 views

Career in RF Engineering [on hold]

I just started my EEEng degree after working IT for about 6 years. I am solely interested in the RF / Communication field. I would like to get involve with Communication companies either in the ...
-1
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0answers
27 views

Selecting an rf Signal Generator [on hold]

I'm trying to locate a signal generator to purchase. Brand and model open, DC to 20MHz, sine and square wave, any other waveforms is a bonus. 1000W or above (yes, I do realise the costs involved) Age ...
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1answer
47 views

Cheap 2.4GHz Antenna Tuning

I am planning on making a board which will have some 2.4GHz RF capabilities, and would like to know if there is a cheap way to tune an IFA cheaply. If I had access to the right equipment I could ...
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66 views

Radio frequency Electronics book [closed]

Could someone would like to give me any books references for a beginner in radio frequency transmission. Thank you for your answers.
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2answers
172 views
+50

Does this simple RF transmitter circuit actually work?

I've come across this circuit a few times while searching for simple transmitter circuits, and decided to try it. According to this site, it should be transmitting at around 90Mhz. ...
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15 views

Reading Mac data of Zigbee protocol stack

I am working on a project using one of the popular Zigbee based RF-MCU Mac-codebases. I have integrated a sensor to the MCU and the same is reading data and I am sending data to the gateway using the ...
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1answer
46 views

ZigBee and Radio Interference [on hold]

What are the mechanisms implemented in ZigBee to overcome Radio Interference?
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1answer
43 views

What does it mean exactly “ averaging over eight symbol periods” when calculating RSS?

When reading about RSSI, I usually found that RSSI is measured by averaging the signal reading over eight symbol periods, I could not understand what does it mean exactly and how RSSI is calculated by ...
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2answers
69 views

Pseudo RF in embedded boards

I noticed that wifi-capable embedded boards integrate the RF into the board design instead of having a separate, add-on wifi card. They have meshes that are etched into the board and the rest of the ...
2
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2answers
66 views

Pass DC through (passive) highpass filter?

Background: I'm a student, working on my final year project. I am designing a front end for a software defined radio. We have an IF frequency at 36Mz (and a BW ~8MHz). We are bandpass sampling this ...
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1answer
34 views

Helical wire antenna normal mode or axis mode?

I have bought theses two RF-transceiver CC1101 module from e-bay(image below), and I want to know if it is a helical antenna in normal mode or in an axis mode. The specification doesn't say anything ...
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3answers
537 views

What will it take to build a DIY 2km (city conditions) RF transmitter (433Mhz)?

This is my first question on this site. I am not an electronics/electrical engineer so pardon my depth of knowledge. I am trying to build an RF transmitter/receiver. These are my end goals : a text ...
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1answer
45 views

coplanar transmission line on both sides of a four layer board

I am designing a four layer board in which i have to run two 50 ohm traces one at the top and other at the bottom side of the board. I have decided to use Coplanar wave guide for both the traces. I am ...
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1answer
49 views

How much RF-interference does a typical desktop computer produce? How much does a metal case without windows reduce it?

It's fairly common now to see desktop computers in cases with large windows cut in the sides. I've always been under the impression that if unshielded, computer equipment will produce a lot of radio ...
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1answer
39 views

pH sensor project: trouble with RF interference

I built this pH sensor project on a breadboard and I'm having a big problem. The output on the voltmeter is completely erratic, and I'm pretty sure it's due to RF interference. When I connect the ...
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0answers
36 views

What's the best workflow for creating gerber files from, say, an HFSS project?

I am curious how everyone gets their RF/microwave designs from their preferred simulation/design suite (HFSS is just an example) into a gerber file for fabrication. What's a good workflow, including ...
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0answers
46 views

How to determine a Signal Generator's Marker (Event) output delay?

I am using an Agilent N5182B Signal Generator for modulating a 2-FSK waveform on a 160MHz RF carrier. For that, I am using a baseband waveform (I/Q mode), generated by a Matlab FSK modulator script. ...
2
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1answer
42 views

Derivation for the skin depth of a wire given RF signal

I was looking at the equation for the resistance of a wire under RF signal and failed to produce similar results. On WikiPedia article on skin effect this resistance is given by: $$R = \frac{\rho ...
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2answers
38 views

RF Combiner Hardware

I have say, 4 170 MHz signals coming in on 4 BNC cables. I would like to add these signals together. Is there a name for a piece of hardware that does this? Are there any special considerations I ...
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0answers
32 views

Controlling a wifi outlet with sensor parameters

I currently have a wireless temp sensor that I can monitor via phone or computer, however I'd like to connect this sensor to a wifi outlet that turns on an a/c or heater. In order to prevent internet ...
0
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2answers
102 views

What's the frequency v power relationship of an oscillator + transmitter?

I'm starting with the assumption that a higher frequency EM wave is more energetic than a lower frequency one and thus requires more energy (and thus more power) to transmit. In my naive model of a ...
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0answers
36 views

Receiver effciency when using DFLL instead of PLL

I have a small doubt! How tolerant are industrial standard receiver chip to phase and frequency error. I bring it out because while designing a transmitter, I want to use DFLL instead of PLL to reduce ...
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0answers
37 views

How to debug and resolve an antenna interference problem?

We have had a board made that features an interacting processor, chip antenna and GPRS/3G module. We have proved the functionality of the board - it works - but the board is not stable. We have ...
9
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4answers
382 views

How is it possible to have a 5W transmitter driving 50 ohms with a 12V supply?

So let's say you have a circuit, which generates a carrier wave at some frequency (let's say 27MHz) and it's connected to a 50 ohm dummy load (which I gather is equivalent to an antenna for circuit ...
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1answer
41 views

Can A HP8756A Network Analyzer Measure The Resonant Frequency Of A GPS Chip Antenna?

I'm wondering if a HP8756A network analyzer by itself is enough to measure the resonant frequency of a GPS chip antenna? The reason I am concerned that it cannot is because I cannot see a "RF Out" ...
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47 views

RF signal frequency vs antenna orientation

I have two CC430s on two identical custom boards and each board has an identical 433MHz RF circuit. The boards are able to communicate with each other only when one of the two boards is placed in a ...
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2answers
57 views

EMF transmission from cell phone's battery

According to Cell Phones & Wi-Fi―Are Children, Fetuses and Fertility at Risk? While one can put the phone in ‘airplane mode,’ which disconnects it from Wi-Fi and the Internet, the cell phone ...
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27 views

Is a wave guide has an ability to narrow radio beam? [duplicate]

If I want narrowing radio beam width to 0.25 degrees range , can using appropriate wave guide make a sense ?
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41 views

De-embedding on ADS: Eliminate the effect of the through-line and just measure the reflection of the load

I measured the s11 of the through-line with the load on the VNA. simulate this circuit – Schematic created using CircuitLab Then I measured the s2p of the through-line itself on the ...
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1answer
88 views

Connecting external 2.4GHz antenna to Intel Edison

I would like to connect an external 2.4GHz antenna to an Intel Edison. According to Mouser, there are different Edison part numbers for different antenna configurations (internal or external). ...
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1answer
57 views

Is the quoted range of an RF module based on two identical modules?

Take for example this 433MHz transceiver module. It's quoted range is 300m. What does this value mean? Is this the distance when the signal strength dies down to 0%? Does this mean if I were to buy ...
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1answer
61 views

Design of 5 - 15 MHz Voltage Preamplifier

I'm trying to design a power amplifier for the HF band to drive an inductive charger. The stage I'm working on now is a voltage preamplifier which needs to be able to amplify 1 Vpp to 10 Vpp. The ...
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1answer
90 views

When is impedance matching necessary? Isn't it much less efficient on all other aspects?

I understand that discontinuities of the physical properties of conductors create reflections much like dioptres reflect a bit of light, but : in which cases does impedance matching become ...
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67 views

Making my own radio transmitter

So I have recently been interested in Radio electronics, and I have been looking around to buy a HAM radio transmitter,but they tend to be very expensive (and you learn nothing by just buying it). So ...
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3answers
68 views

Calculating gain of multiple antenna system

Some radars have thousands of antennas, there are also some routers that have multiple antenna systems. But I want to know how to calculate total gain of multiple antennas in a system? Is it simply ...
4
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1answer
64 views

ZigBee vs WiFi for wireless communication

I've been working on a product using WiFi. The reason I picked WiFi, is cause I essentially have 20-30 nodes communicating to a main node via a router. This all works very well, and its easy as its ...
0
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2answers
112 views

Is possible to build -168 dBm amplifer?

we know that GPS receiver can reach sensitivty of -168dBm, and also it is possible to make receivers with similar sensetitvity can operate at another bands/frequencies . but I just want to know if ...
2
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1answer
314 views

What is an antenna amplifier ? How does it add gain?

I don't know what exactly does antenna amplifier mean. Is it possible to increase the gain of a Tx antenna ? Where do I connect the antenna amplifier to it ? If, for example, the Tx has a power of 20 ...
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1answer
49 views

Replace Electret Microphone With Arduino Output

I have the following circuit for a simple FM transmitter. I want to replace the electret microphone with a simple tone generated by an Arduino (or equivalent) that will be broadcast over FM radio. ...
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42 views

How does a chipset determine which LTE bands it supports?

Take the snapdragon 800 and 801 chipsets. Both use the same hexagon DSP http://pages.cs.wisc.edu/~danav/pubs/qcom/hexagon_hotchips2013.pdf But a phone on verizon will only support LTE bands 4 and ...
0
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2answers
71 views

How can I tap into and measure this rf frequency?

I'm new to rf design, although I'm learning rapidly. I've designed a PCB which uses an ultra-wideband (UWB) transceiver. The center frequency is selectable between 3.6GHz and 6.5GHz, with 500MHz ...
0
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1answer
82 views

Just I want to understand gain, power, link budget

I am a beginner, I am confused about calculating the nessecary gain and power and sensitvity to overcome path loss at certain distances. the first thing what does gain mean ? I am not talkink ...
0
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1answer
53 views

If I connected N numbers of amplifiers each have X gain 'dB“ and Y power ”dBm", how to calculate total gain and power?

sorry for bad description, I am a beginner. my question is just for knowledge and I did not test anything. If I connect for example 3 amplifier , each one has 60 dB gain and 15 dBm power. can we ...
0
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0answers
20 views

How to modulate RF signal using LabView? [duplicate]

I am using Acousto-Optic Modulator (AOM) in my experiment to modulate laser light using controlled modulations in phase and intensity of RF signal being fed into the AOM. I want to know what program ...
0
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0answers
37 views

PCB specifications for 2.4 GHZ RF Board

I am designing an RF module with a PCB trace antenna. I'm wondering what PCB specifications will have a significant effect on the quality of the RF Signal. Is there a prefered laminate and immersion? ...
2
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1answer
74 views

Rogowski Coil High Frequency Limit

I'd like to do some experiments involving high frequency (1.296GHz to be exact) that involve an 50ohm inductor that has minimal RF losses. The obvious candidate is to drive a Rogowski coil (driven as ...
2
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2answers
116 views

Are the stock transistor models in LTspice accurate at RF?

Just checking, I'm doing some experimenting of small signal RF design in LTspice.
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1answer
48 views

Modifying an amp evaluation board to bias the coax?

I'm normally a software guy, but a recent project requires me to dip my toe in the ocean of electrical engineering. I'm trying to (cheaply) capture GPS signals to process in software, and I have an ...