Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange
Make your voice heard. Take the 2019 Developer Survey now

Questions tagged [rf]

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.

1
vote
2answers
79 views

Project - How to onstruct a circuit to introduce and control a 0-300ms delay in an RF feed from a Sky Box to multiple TV sets? [closed]

Just bought a new TV! It's "smart" but where my previous dumb TV didn't, my smart TV introduces a delay over HDMI from my Sky+HD box compared to the RF2 output which is wired via coax cable to the ...
3
votes
5answers
1k views

How do microstrips actually represent lumped components?

I'm having trouble understand intutively how microstrips repersent lumped element components. All we are told is that, high impedance sections on a microstrip line repersent inductors and low-...
0
votes
1answer
29 views

How to stop erroneous signals on startup of an RF circuit

I have a really janky setup where I'm using an ESP and some transistors to "push" the buttons on an RF remote control, used for controlling electrical outlets. The circuit works perfectly during ...
1
vote
0answers
32 views

Creating a balanced dipole from two monopole chip antennas for use on small PCBs

I'm trying to use a monopole chip antenna on a PCB much smaller than the one recommended in the datasheet. I am wondering if I can get away with a much smaller board by using two monopole antennas ...
0
votes
2answers
70 views

I don't know how to choose an adequate antenna

I need to choose an antenna for a long range free space communication (~10km), and I currently have a receiving antenna, but I don't understand enough to be able to pick an adequate emitter. The ...
1
vote
1answer
33 views

Equivalent Series Resistance of 13.56 MHz RFID Antenna

I am designing a system that uses the MFRC522 by NXP Semiconductors and I am having a bit of difficulty designing the antenna. NXP provide an antenna design guide under the application note AN1445 ...
0
votes
1answer
68 views

How to design RF PCB to ensure the 50 ohm impedance

I do not have any experience designing RF circuits and I am finding many challenges for my project. One of them is to match the 50 ohm impedance that some components demand. In the input of my PCB I ...
-1
votes
1answer
51 views

My mobile detector circuit won't work

I'm trying to get C3 to detect RF signals from a mobile phone. Amplify this signal to detect it using an LED. My main issue is simulating the antenna on multisim since multisim doesnt have an antenna!...
0
votes
1answer
74 views

Generating a realistic sine wave in MATLAB

I'm working on a simulation on MATLAB and I need a realistic sine wave which has harmonics. So I know there would be harmonics at 2f,3f... but I am not sure how to determine their amplitude. I tried ...
0
votes
1answer
54 views

How to find new ABCD parameters when reversing 2-port network

I have an ABCD matrix represenataion which is defined as: For such a problem, what approach should I follow in order to organize the new ( reversed) network ports voltages and currents properly. I ...
0
votes
0answers
37 views

Propagation Constant in Transmission Line - Approximation

This is more of a math question but I feel like the maths.stackexchange people won't like these approximations hence I'll stick here. I'm trying substitute in the conditions for a low-loss ...
-1
votes
1answer
30 views

How could i calculate the voltage induced in a detector circuit by picking up RF signals from a Mobile phone?

Is there any formula/equation i could use to estimate the voltage induced at the input from the RF signals?
1
vote
0answers
35 views

Near-me area network embedded emitters with a Raspberry Pi server receiver

I am making a toy for 4-year old children with 10-20 pieces in wood, as in this picture with four wooden boards with names: The goal is that each wooden board triggers a sound, such as "Hello" or "...
0
votes
1answer
67 views

Easiest way to find transfer function of a lossless ladder filter after we finish design?

I have completed my Lossless Ladder BPF design, but I don't know how to find the transfer function of the resulting circuit without going through the slow and rigorous process of getting resistances ...
1
vote
2answers
42 views

Impedance control for small antenna feed?

I have a BLE board with a 1/4 wavelength antenna and a feed that is about 12mm long. The wavelength of 2.45ghz is 122mm. I've seen various discussions saying anything over 1/10 the wavelength you ...
0
votes
1answer
90 views

RF switch acting like a splitter

I'm trying to use a pair of RF switches (SKY13421-486LF) to switch two channels between the circuit output and a matching resistor: I have two inputs and want to pass one to the output and dump the ...
1
vote
1answer
111 views

RF Splitter/Combiner with vectors in phase and antiphase - Where does the power go if they cancel?

Updated I have a RF splitter/combiner. I am focusing on the black and red vectors. (Picture attached) When the black vector of 0.25V and 0 phase enters the box, it will split. 1/sqrt(2)*0.25V at 0 ...
1
vote
1answer
35 views

Matching Networks on Narrowband Multistage Low Noise Amplifier (LNA)

How does the inter-stage matching network of a narrowband LNA compare to that of a wideband LNA for the same multistage design? I've read somewhere that narrowband LNA does not necessarily require a ...
0
votes
3answers
68 views

Why does antenna tuner in crystal radio use capacitor and an inductor?

I know that antennas can be capacitive or inductive depending on the relation of antenna length to the \$\lambda\$. I know that crystal radios use both antenna and capacitor for tuning and I don't ...
0
votes
2answers
53 views

Why are so many RF remote boards relay-based?

I'm working on a device that illuminates a signal LED when a button on a remote is pressed. I have a working prototype based on a pre-fabricated board I bought on Amazon (see here), and it's nice! But ...
1
vote
1answer
91 views

RF Development board layout questions

I was looking at the development board layout for the MMZ09312B and I had a few questions: datasheet: http://cache.freescale.com/files/rf_if/doc/data_sheet/MMZ09312B.pdf Are large polygon pours away ...
0
votes
2answers
47 views

RF Antenna design for 2 different operating frequencies

I have noticed that my mobile phone sometimes shows it is using the 3G and then other times the 4G. How is that possible if they are using the same antenna? I assume it would use a microcontroller ...
0
votes
1answer
46 views

RF measurement setup

I'm trying to take a simple measurement of ~2.4 GHz (WiFi land) with an RF spectrum analyzer (Tektronix RSA607A) but have so far been unsuccessful. On the RF In ...
-5
votes
3answers
123 views

bike won't start until rider wear helmet [closed]

I am trying to make a project in which ignition system of bike will not start until the rider would wear a helmet. This can be done through RF Transmitter and receiver, but how it will be achieved? ...
0
votes
1answer
81 views

Connection between RF output to the source for minimum loss and maximum power transfer

The bottom device in the left image is an RF generator with ratings 230V, 15A (max), 13.56 MHz and variable controllable output power up to 1250 W. The top device is an auto match. The metal strip ...
0
votes
1answer
62 views

Commercial broadband RF amplifiers

In the process of designing a broadband RF amplifier, I've come across some commercial boards, claiming gain flatnesses of +-1db from DC to 1Ghz. Those boards are ridiculously simple, having only one ...
0
votes
0answers
17 views

Determing proper wireless parameters for HMTRP radio module

I'm trying to properly setup an HM-TRP FSK radio module to send and receive data the best it can at 56kbps. I think I'm wrong with setting it up to use 600Khz "receive bandwidth" and 160Khz "modulate ...
0
votes
1answer
34 views

Trying to read the data from an ASK RF transmitter

I'm trying to duplicate the operation of a simple RF remote control (for some remote power outlets). In the remote control there is an unmarked 8-pin microcontroller. I've worked out which pins are ...
0
votes
2answers
37 views

What is a tone (in context of IMD)?

I've seen the term "tone" used a lot in RF literature, but haven't found any helpful explanation of what exactly a tone is. I am looking at tone in context of IMD; i.e. the fundamental input tones. ...
2
votes
0answers
45 views

Question related to two closely separated signals that need to be analyzed by a spectrum analyzer

Question The settings of a spectrum analyzer are given as following: Center Frequency = 1.89 GHz, RBW = 10 kHz, VBW = 10 kHz and Span = 50MHz. The Reference Level is set to -20 dBm and ...
1
vote
1answer
52 views

Question related to the interference seen at the spectrum analyzer's receiver

I am preparing for the RF course exam. I have an old question on hand that I am trying to solve. Please review my attempt. Question: A simple spectrum analyzer with superheterodyne receiver ...
1
vote
0answers
53 views

Electro magnetic interference with Arduino Uno and a portable radio

I'm surprised when I'm working with Arduino Uno, by just sitting beside a portable radio, like when I was powered on both Arduino & Radio and when they are close to each other I got some noise ...
17
votes
4answers
4k views

Why are there so many vias on this board?

I was looking at the MMZ09312BT1 development board layout, and I was curious about all the holes they have on the board. Are these vias? What is their purpose (I heard somewhere that they are meant as ...
0
votes
1answer
38 views

Receiver Antenna Gain

How is gain defined for a receiver antenna? If we look at a radiating antenna, there is a Pin, and the gain in a particular direction would be the radiation intensity Ur, divided by the radiation ...
0
votes
2answers
133 views

Why aren't tethered balloons used instead of Cellphone towers? [closed]

If we use tethered balloons with wireless gateways fitted on them (let's say for Cellular or LPWAN communication), they can provide much more coverage. Why aren't they used then? While there are many ...
9
votes
5answers
1k views

Difference between these RF adapters

Can someone explain me the differences between these two RF adapters. I know the one on the right is better (and much more expensive as well) but is there a difference in the functioning of these ...
0
votes
1answer
17 views

Connected RF Trace to Multiple Pads

I'm trying to improve my RF routing skills. I want to connect a 450 MHz trace (21mil width) to a RF6886TR13 power amplifier that has 6 RF_OUT pins. What is the best way to make this connection? I've ...
0
votes
1answer
39 views

How to determine the frequencies in which the L&C model of an artificial transmission line works?

I want to model an artificial transmission line with L & C. So far I used the following circuit and used the values of L=400 pH and C=0.16 pF so that Z=sqrt(L/C)=50 ohms. So, expected S21 and S31 ...
0
votes
1answer
29 views

How exactly averaging is performed in the diode sensor based power meter?

I was just wondering how the power averaging works in the diode sensor based power meter. Can you please enlighten me? Thank you.
1
vote
1answer
106 views

How to convert Inductor to series transmission line?

My objective is to understand the travelling wave amplifiers, but I am stuck on how to realize inductors in transmission lines. But, I am basically stuck on how to convert a series inductor to a ...
-1
votes
0answers
25 views

Relationship between RBW and sweep time in time-domain and frequency-domain of a spectrum anaylzer?

In frequency domain of a spectrum analyzer, e.g., from Agilent, if RBW increases, then sweep time decreases. However, my observation in time domain of the spectrum analyzer (i.e., at zero span) is ...
0
votes
1answer
51 views

How to design a 180 degree phase inverter for the feedback?

I am currently working on a multi-stage wideband amplifier (80-110 GHz) design with the goal of having 5-6 dB for each stage. The transistor that I am using has the transit frequency around 300 GHz (...
3
votes
1answer
209 views

The S parameters of an attenuator--but what is actually wrong with it?

I have measured S parameters of an 10 dB attenuator on hand--please see the attachment. In my view, this attenuator is not performing as expected, e.g., |S12| / |S21| is not giving 10dB attenuation ...
0
votes
1answer
34 views

In what way VBW and trace averaging are different in spectrum analyzer?

We know both VBW and trace averaging intends to smooth the fluctuations of a spectrum. But how do they differ from each other?
0
votes
1answer
71 views

Impact of “reference level” and “RBW” on the time domain signal in spectrum analyzer?

Two questions: (1) What is the impact of "reference level" on the time-domain signal viewed on the spectrum analyzer? [My attempt] Mean power level of a time domain signal would move up and down on ...
2
votes
2answers
47 views

Questions related to the calibration of a VNA?

I am seeking answers to these two questions related to the calibration of the VNA. (1) What type of VNA calibration is required to measure the reflection, transmission, and phase of an attenuator? [...
2
votes
1answer
85 views

Converting dBuA to dBuV at 3m and 10m

I'm looking for some advice on converting from dBuA/m to dBuV/m at 10m. I'm trying to convert 10dBuA/m @ 10m. I'm struggling with the uA to uV conversion at distance and can't find online tools to do ...
-1
votes
0answers
22 views

Zigbee power amplifiers

Zigbee transmitters uses OQPSK combined with half IF pulse shaping which results in a signal having a constant envelop and which does not suffer from linearity issues and thus can be driven close to ...
0
votes
1answer
70 views

Matching impedance network for an LC ladder network

Let's say I have a 5 stage L-C ladder network with L= 4.7 micro Henry and C= 60 pF. The characteristic impedance of the network becomes 280 ohms (square root(L/C)). However, from circuit analysis, the ...
3
votes
1answer
70 views

RF layout bend over Component

We lay out the RF trace for below model. GSM 900MHz RF trace maintain at 50Ω impedance. As I know, the RF trace needs to be as short as possible for better signal. Do we need to bend RF trace ...