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.

learn more… | top users | synonyms (1)

0
votes
0answers
10 views

CST 3-D FDTD simulation

I am working on FDTD simulation of any space. I can work with Matlab and C code for 1D and 2D case but for 3D case it becomes complicated so I want to use CST microwave studio. I want to run simple ...
3
votes
1answer
74 views

40 GHz spectrum analyzer with N-type coax input?

We have an old Rohde & Schwarz FSEK 30 that is advertised as having a range from 20 Hz to 40 GHz, with an N-type input connector. My conundrum is that a type-N connector with air dielectric ...
0
votes
0answers
24 views

Listening below the carrier frequency gives a weaker signal than above the carrier frequency - why? [migrated]

I have a 20m CW transceiver with an option for a wide or a narrow filter. When the narrow filter is selected, a crystal ladder filter is used in the intermediate frequency filter, between two mixers. ...
0
votes
1answer
39 views

Cheapest Bidirectional NFC With Android Phone

I'm trying to build a handheld device which can communicate bidirectionally with an NFC-enabled Android phone. Generally, the phone will send some arbitrary command, and the handheld would then ...
0
votes
0answers
39 views

Choosing a DAC for Amateur Radio applications

I'm looking to make a software defined radio, and I'm currently looking at what DAC to choose. I'm fairly new to this area of RF design, so I don't know what specs to look for. Most of my signals ...
0
votes
0answers
5 views

Is this Bluetooth module cool for Arduino? [migrated]

I am making a basic project that will have 4 or 5 arduino nodes. Each arduino will have a bluetooth module attached. The thing I want is, I want to be able for each one of these arduinos to know the ...
-1
votes
3answers
278 views

Is it possible to exchange information between arduino and android phones easily using nrf24l01? [duplicate]

I need to send information from arduino to an android phone, having some app actively listening for radio communication from arduino. Using nrf24l01 is that possible? The best scenario would be ...
0
votes
1answer
83 views

why does a x100 oscilloscope probe grant a wider bandwidth than a x10 probe

I was asked in an interview the question "why does A x100 oscilloscope probe grant a wider bandwidth than a x10 probe? How much does it widen it?".
2
votes
0answers
38 views

Increasing RF24 range using an antenna

First time poster here on electronics, so please excuse any big mistakes. I'm working on a project that uses the NRF24L01+ chip for radio communication between an arduino uno and a raspberry pi. It ...
0
votes
2answers
51 views

Controlling a simple RC vehicle at long dinstace from a PC

I would like to control a simple, ground-based vehicle wirelessly, at ranges up to 5-6 km. The communication would be bi-directional (to get a feedback of "command received") but would only require ...
0
votes
2answers
59 views

Antenna VS Coil

So I sorta understand that antennas are just wires connected to a signal out with no reference to ground. (That's for a different question) How does a coil/inductor with one side attached to v+, one ...
0
votes
0answers
66 views

If my WIFI chip has poor performance at 5GHZ, what does that mean to the end user?

I'm testing my WIFI chip, and it has poor performance at 5GHZ. The transmit power I'm measuring is really low. How does this problem manifest to an end user? Will the internet connection be really ...
0
votes
1answer
47 views

using supermalloy as the core for wifi loop antenna

this is an extension of this question: Why aren't ferrite rod antennas used in WiFi? if you don't want to go through the previous question, then basically i was asking if we can loop wifi ...
2
votes
3answers
172 views

How can I send one bit one mile with one battery?

This summer I will be attending a large music festival for the second year. I will be going with other people this time, and I'd like to be able to communicate with the other people wirelessly in ...
0
votes
1answer
50 views

How does a microwave oven-leakage detector work?

What type of sensor or circuitry is inside one of these devices that allows measurement of microwave radiation strength? I've never opened one but I'm assuming it's similar to measuring RSSI on a ...
0
votes
2answers
53 views

What does blocking performance mean in RF transceivers' datasheet?

I have encountered two terms, adjacent channel selectivity (ACS) and blocking performance (BP), in TI cc1120's datasheet (http://www.ti.com/product/cc1120). I found the definition of the former (ACS) ...
0
votes
1answer
19 views

Isolation spacing in CPW-G

Is there any thumb of rules how to determine optimum spacing (marked with S below) for a RF signal (@2.45 GHz) on Coplanar Waveguide with ground (CPW-G)?
0
votes
2answers
58 views

How can the 2.4GHz ISM band have 130+ channels?

I am a relative beginner regarding wireless communications protocols and I am looking into the protocols used by toy helicopters, in particular the Hubsan X4. According to more experienced people who ...
1
vote
1answer
46 views

How to terminate a coax connection into a receiver for best common-mode rejection?

I am designing a simple HF receiver as a hobby project. The design is similar to the SoftRock Lite II, and the antenna input looks like this: The SoftRock design doesn't really say how the inputs ...
0
votes
0answers
27 views

Voltage Across Patch Antenna and Power Output

I'm modeling a patch antenna using two copper plates (ground plane and patch), ceramic in between the copper plates, and a lead connecting the patch and ground plane that runs through the ceramic in ...
2
votes
1answer
95 views

Would an RF amplifier be required for an indoors antenna connected via coaxial cable to an outdoor directional antenna (900/1800 MHz)

Sorry, couldn't make the question title any shorter without losing meaning. So, I'm looking to build an outdoors yagi antenna that's connected to another indoors antenna via coaxial cable. The ...
2
votes
1answer
70 views

RF PCB design: right angles in components?

For RF pcb design, it's common knowledge there shouldn't be any right-angle traces, because capacitance increases in the corner, changing the impedance and causing signal reflections. Less clear (to ...
0
votes
1answer
56 views

How to listen to radio communications from a transmitter?

I have two devices communicating at a frequency which I don't know. I want to listen to that communication so that I can replicate one of the devices and fool the other. Basically I want to reverse ...
1
vote
1answer
45 views

Estimating the schematic of a black box using the measured impedance curve

I need to estimate/predict the circuit design of a black box using the measured impedance at the output of this box. The only hint I have is that the circuit inside the box is a demodulator. Is it ...
0
votes
2answers
40 views

Antenna efficiency and PCB impact

I'm trying to improve the range on my 433 MHz radios and came across http://www.att.com/edo/en_US/pdf/AntennaFundamentals.pdf. (Geez, there's so much RF information in many bits and pieces, if only ...
0
votes
0answers
51 views

PCB ground shields

I'm trying to maximize the range on my 433 MHz radios and came across this article by TI: http://www.ti.com/lit/an/swra367a/swra367a.pdf. In section 3.5, they specify that your ground plane should be ...
1
vote
0answers
58 views

Measuring distances electronically? [closed]

Is there any way currently known that can accurately measure the distance between two objects. Say a phone and another device like a chip or another phone. basically measuring distances ...
0
votes
1answer
58 views

Multi Stage Passive Filter Design [closed]

I'm playing around with some simple RF beacons, many of these use a multi stage LC ladder to filter the outgoing signal after passing through a class C amp. Can anyone point me to a good ...
-2
votes
1answer
64 views

Long-range RF comm with decent data rate [closed]

I'm building a quadcopter powered with Arduino. For testing purposes, I'm currently using bluetooth. In the future, however, I would like to have some form of fairly long range communication that also ...
3
votes
1answer
116 views

How to analyze analog circuits with transistors [is this circuit immediately analyzable to anyone]?

I'm not experience in making electronics, but I do have a working knowledge of basic circuit laws and such, but we never covered something with transistors such as this BFO metal detector circuit I've ...
1
vote
0answers
37 views

Shared feed/GND pad on Pulse W3011 antenna

This is my first post; sorry if I've unwittingly broken any rules or accepted conventions around here... I'm using a Pulse Engineering W3011 ceramic GPS antenna. As is common with these small ceramic ...
1
vote
1answer
47 views

Why does timing change in dataframe using Manchester encoding

I have successfully received a couple data frames from an RF transmitter. I compared couple consecutive frames and the timing deviation between them is marginal, so I am convinced it is reasonably ...
-1
votes
1answer
69 views

Cell phone detector circuit design [closed]

This circuit I found on the internet detects mobile frequencies that transmit to the base station in the range of (0.9 to 3 GHZ). I want to understand how can I get or calculate the values of some ...
1
vote
2answers
46 views

What are the trade-offs of transmission bands?

If I were designing an RF circuit how do I determine what band the circuit should operate on? What are the trade offs? and why is the higher the frequency the lower range? It is quite un-intuitive for ...
0
votes
1answer
57 views

MHz oscillator probe impedance?

I find something weird going on in my 100MHz oscillator probe. I always thought the probe has a resistance of 1M ohm, but apparently at 13MHz, when I put a 2.2k ohm resistor in series with the probe, ...
1
vote
1answer
56 views

Improving RF sensitivity

I'm trying to improve the range on my 433 MHz radios that are using the CC430F5137. Based on 25.3.3 in http://www.ti.com/lit/ug/slau259e/slau259e.pdf, it seems like decreasing the RX filter BW can ...
0
votes
0answers
40 views

Rf amplifier in AM receiver

I have an Analog electronics class project about AM receiver. In the project, it is stated that RF amplifier will be used after antenna. What kind of amplifier is this RF amplifier, voltage, current ...
0
votes
2answers
63 views

Buffering/matching large signal to drive 5 ohm capacitive load at 13MHz (RF)

I built a Pierce oscillator that generates 13.5MHz @ 7Vpp signal from a V_cc=12V. But I need to drive a capacitive load of 5 ohms @ 6Vpp. I'm not sure how to do this. First I need a buffer to prevent ...
1
vote
1answer
39 views

How to detect several agents within a radius, what is the best and easiest way to do it?

I have a room with 30 objects which may or not be present, and I want to be able to detect which objects are in the room. My first idea was to attach a RFID tag to each one of these objects and have ...
1
vote
0answers
49 views

Self-oscillation in a commercial RF amplifier

I purchased several 50 ohm (in/out), 35 dB gain photomultiplier tube (PMT) amplifiers from a vendor assuming I could use them to read out the voltages on my PMTs. The amplifiers are AC coupled with a ...
0
votes
1answer
63 views

Switching between transmit and receive in a transceiver

My current project involves building a proximity sensor that uses RF and is low-cost (so no microcontrollers). I've come across two circuits that look quite promising, a transmitter and a receiver. I ...
0
votes
1answer
66 views

TI CC2538 radio turns off after connecting UART

Need help regarding Texas Instruments CC2538 RF module. (https://store.ti.com/CC2538DK-CC2538-Development-Kit-P4532.aspx) The module has an operating range from 2.1V to 3.6V I'm trying to use the ...
2
votes
1answer
34 views

Analyzing reflection and transmission without a VNA

The wikipedia page for network analyzers mentions "reflection and transmission of electrical networks are easy to measure at high frequencies" but doesn't give any hint on how this is done or what it ...
4
votes
1answer
137 views

Impedance matching with only capacitors?

I need to do impedance matching for 33 + j32 ohm source and 16.5 + j0 ohm load. The copper traces adds 99 ohm impedance and 20 degree electrical length. According to smith Chart below, I need to use ...
0
votes
0answers
64 views

cellphone detection

I'm searching for advice of how to detect cellphones. So, I think that I need a Radio-frequency detector. From the scratch I'm planning to use arduino with some-board (or make it by myself). There are ...
0
votes
1answer
36 views

How to determine dielectric constant and loss tanget of a PCB board at a specific frequency?

I need to know dielectric constant (relative permittivity) and Tan loss of a FR4 board at 2.45 GHz. The specification of the manufacturer is as it is below: Dielectric Constant: Test method ...
0
votes
0answers
42 views

How to De-embed 3-port Network on ADS

ADS 2013 no longer has odd-port de-embedding. I want to eliminate the effect of a 3-port balun board on the measurement of the antenna. How can I do that in ADS? I tried using a 4-port de-embedding ...
4
votes
1answer
48 views

How to minimize characteristic impedance mismatches caused by vias?

This question springs from an answer here. When using stripline configurations for rf signalling, the conductors are routed on an inner layer of the pcb, sandwiched between two ground planes. I ...
2
votes
2answers
57 views

Which of these Stripline Impedance Calculations is correct?

Different sources are giving me drastically different characteristic impedance values, and am hoping someone will verify them for me. Generally, with microstrip, I start with an online calculator to ...
1
vote
2answers
38 views

Shared antenna on multiple 2.4Ghz receivers

I want to use several 2.4 Ghz transcievers (not sure which IC yet, either Atmel AT86RF*** or TI CC) in order to build a simultaneous multi-channel sniffer. The transciever output is differential. I am ...