Tagged Questions

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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33 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
42 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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31 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
40 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
55 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
39 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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0answers
52 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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0answers
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
61 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 ...
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0answers
40 views

heavy urban 1200 km best band ? with no sky support [closed]

what is the best band can propagate 10 kbps of data from chicago to newyork by direct wave or groundwave "no any skywave support" ? how to calculate path loss at this long range ?
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1answer
56 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 ...
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2answers
108 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
296 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
40 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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0answers
36 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 ...
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2answers
58 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 ...
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1answer
68 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 ...
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1answer
48 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 ...
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0answers
37 views

Can't transmit a BPSK modulated signal

I'm currently working on a BPSK transmitter and receiver. The problem is I don't know what I am missing and can't transmit/receive a data. My supply is 12v and -12v. So I'm trying to send a varying ...
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0answers
18 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 ...
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0answers
35 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
64 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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1answer
89 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
42 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 ...
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0answers
29 views

Measuring RF Noise of Electric Train

I live near an old electric trolley, and I've noticed that it apparently interferes with RF signals. In particular: I notice that when I drive next to the line my satellite radio drops out. My ...
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1answer
53 views

Why is my guitar amplifier acting like a radio when I touch the volume knob?

I just bought an acoustic/electric mandolin (Ibanez M511SE-DVS) that I decided to test out with the only guitar amp that I have (a Baja BG-10). It works fine, but I noticed that when I have my finger ...
1
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1answer
32 views

Comparator input interfacing

I need to digitize a weak (-10 dBm) 1-20 MHz signal with a comparator. The output of the preceding stage is 50 ohm. The comparator I'm using is the LT1715. It's input trip point is ± 5 mV and the ...
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2answers
41 views

Passive Filter Negative Insertion Loss

Can someone please explain to me how a passive filter could possibly have a negative insertion loss? In the attached picture, this can be seen in the C or D curves where the insertion loss dips below ...
0
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0answers
25 views

Agilent N9330B for Antenna development?

We are considering buying an Agilent N9330B for using to match the antenna on our product. The antenna is a PCB etched design on the board. Our frequency range is GSM and 3G so about 800 to 2100 MHz. ...
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3answers
64 views

Waterproofing a GPS antena

I need to use this GPS antenna on a model boat. As a result of placement, it will be submerged periodically (though I don't expect it to work while submerged), and damp often. What can I encase it in ...
0
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0answers
102 views

433MHz quarter-wave length antenna: Longer is better?

I am trying to conduct an RF project using some cheap modules: link here My problem is that even though most blogs and Google searches for these modules use a quarter-wave length antenna (roughly ...
0
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0answers
41 views

Experiment using wifi frequency(Wisee) - SDR is the best equipment?

I'm going to do an experiment using Wifi frequency (2~5 Ghz). I need some equipment to generate and receive this 2~5Ghz frequency. I'm currently quite new to this field (RF) - currently majoring in ...
4
votes
2answers
125 views

Can't understand Frequency and Bandwidth [duplicate]

I just don't get it. How bandwidth is the factor that the data rate and the capacity are based on? Let's say we're using Amplitude Modulation. The main factor here is the ability to change the ...
0
votes
1answer
126 views

Length of a 40MHz antenna

A few days ago I had the brilliant idea of replacing the ugly antenna of a 40MHz car remote control with an extendable one. Now the range decreased from 50 meters to 3-4m. I don't know exactly what I ...
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0answers
40 views

How to measure RF receiver

I am trying to check how electric devices such as Sunroof could affect the remote key performance range (meter) for cars. I am thinking of measuring relative antenna gain of RF receiver of one test ...
1
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1answer
69 views

Estimating Path Loss from Measured 2.4Ghz/Wlan Signal Strength to get Distance

I want to estimate distances between Wlan Routers based on the RSS (received signal strength) indoors. Im fully aware that I only will get rough estimates. For that I studied some radio propagation ...
3
votes
1answer
108 views

Multiple nrf24l01, shared power, ripple/interference, DSO screenshot provided

I've got this circuit with 3x atmega328 & nrf24l01+ running off shared power supply, either 2x AA battery or 3v3 reg. It acts as a repeater, and depending on the origin of the message and the ...
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0answers
31 views

How would I go about analyzing this SDR-captured 300mhz AM radio signal?

I am attempting to reverse engineer the signal from a 300 mhz garage signal as a learning experience rather than an exercise in efficiency.My intent is to purchase a 300 mhz broadcaster IC and connect ...
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1answer
34 views

My Rf reciever circuit on battery ,but not with a rectified xformer output as source

I just made a Rf circuit that turns on and off a relay depending on the transmitter's message The circuit is working fine when i connect it to a 9v battery. But i cant get the circuit to work with ...
2
votes
2answers
64 views

Balanced line impedance matching

Is there a way to convert a 100Ω balanced connection to a 200Ω balanced connection without using two baluns? I have a 2.4GHz baseband that I want to attach to a front end, but the baseband ...
0
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0answers
36 views

Fixed Frequency Synthesis with PLL

I'd like to design a downconverter with a fixed local oscillator frequency ~2GHz with fairly good stability. I understand that the best way to do this is a PLL with a fixed crystal oscillator and a ...
1
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3answers
89 views

How to chose an IF, or how bad is zero-IF really?

In a superheterodyne receiver, what must one consider in order to chose an intermediate frequency? Specifically, I'm working on a radio telescope project. It is basically a superheterodyne receiver ...
0
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1answer
38 views

How to determine antenna noise power?

For a 1.4 GHz radio telescope project I'm working on, I need to know the power level of noise an outdoor dipole antenna will be outputting in order to determine the amount of amplification needed. ...
3
votes
1answer
86 views

Analyzing this RF circuit

I'm trying to analyze this RF circuit: This circuit is designed for about 915 MHz operation. I'd be happy in fact understanding this smaller section of the circuit: I have been trying to find ...
1
vote
1answer
47 views

Exchanging packets over an nRF24L01+

I have two nRF24L01+ chips each attached to a Bus Pirate. I'm trying to write some code to test exchanging packets between them, at first entirely on my laptop before I eventually move out to an AVR ...
0
votes
1answer
44 views

Impedance line matching and component value matching

I have the following circuit for the SIM900's antenna connection, using the A10393 antenna from digikey: In closer look: First of all my knowledge on RF design is not great. My questions now are ...
1
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1answer
81 views

RF load (terminator) at the end of RF attenuator

Do I need to install RF terminator at the end of RF attenuator? Let's say that max power output for RM port is 50W and I'm using 100W 50dB attenuator. What if I was using 50W 40dB attenuator? Is there ...
0
votes
2answers
217 views

2.4 GHz versus 434 MHz transceiver for home automation

I am working on a project that uses an Arduino Uno R3 and will have one receiver and one transmitter. I'm going to use this for home automation within my home in India. I want to know which ...
2
votes
1answer
64 views

Is RF Transformer Impedance Significantly Affected by Wire Size?

I'm building a Softrock Ensemble III HF Receiver. The online instructions are pretty good, but have a few remnants from an earlier version that no longer apply. So, despite the discussion about the ...