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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1answer
176 views

Can anyone explain this capacitor setup? “repairing old tube radio”

I'm trying to figure out whats going on with these capacitors so i can replace them in a old tube radio but I don't understand why there connected in this way. simulate this circuit – ...
0
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1answer
29 views

Transmission of numeric data using atmega 16 and 433MHz transmitter and receiver

I've been working on embedded systems for quite some time now and I know that we can transmit signals into a microcontroller using a 433MHz transmittor and the MCU accepts it as if a button was ...
0
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0answers
24 views

Is it possible to use the DASH7 protocol in an arduino? [migrated]

I've been reading about the protocol DASH7 but can't find much documentation about it. There seems to be a protocol stack called OpenTag writen in C and I want to know if there is something familiar ...
0
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1answer
19 views

RF Receiver for 433mhz and 315mhz?

I have a XD-RF-5V receiver wired to my Raspberry Pi listening with RFSniffer (433Utils). I also have a XD-FST 433.92mhz transmitter wired to my Raspberry Pi running codesend (433Utils). I can ...
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5answers
68 views

Does increasing the amplitude of a signal also increase the data rate?

I face an ambiguity when considering the carrier frequency, signal frequency, bandwidth and data rate. When I consider the Shannon formula, I wonder if increasing the transmission power also means ...
0
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2answers
25 views

Dipole antenna VS. coil for RF transmission or recieving

Correct me if I am wrong, but all RF light waves are created via a changing electric and magnetic field. But when looking at all kinds of radios and RF circuits, this light wave is always made with a ...
1
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1answer
53 views

Reliable way to transport data over 1-2 km distance

I am looking for some way to transport data (around 3000Kbps) omnidirectional. Transmitter should not weight more than 300 grams but receiver can be much heavier. The range I am trying to achieve is ...
-1
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1answer
30 views

Detecting RF and converting it to Wattage [closed]

By what elements or components i would be able to detect a particular 2G frequency ? I want to detect a particular RF and display it in terms of Wattage ?is it possible ?
0
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1answer
44 views

900 MHz FSK Receiver Stage

I am designing an FSK transceiver that operates from roughly 902-928 MHz with at least 18 possible channels. Using the 5-bit DAC in my microcontroller, I plan to control a Crystek VCO ...
4
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0answers
30 views

Threaded alternative to MMCX connectors which mates to RG-316/U

I'm currently in the process of redesigning the RF section of a communications system for a cube satellite. There are two PCBs in this system: one containing the down/up converters and modem, and ...
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1answer
38 views

Using HT12E/D with RX/TX 433Mhz modules

i have ht12d and ht12e ic's and rx tx 433Mhz modules. i arranged the ht12e to the output port of Microcontroller and connected the ht12e to transmitter and similarly to the recieving side. is it now ...
0
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0answers
52 views

Long range RF transmitter and receiver

Recently I made some upgrades to my quadcopter and I would like to improve my transmitter/receiver range. Currently I can fly up to 1.5km far, which is not bad but I would like to fly about 8 km far ...
0
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3answers
76 views

RF attenuator resistors

hi i am trying to find a formula to reduce 1 watt 1000mw to 0.5 watt 500mw RF basically cut the rf power in half using an attenuator which kind of resistors would be best for this has to be ...
0
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1answer
52 views

Frequency vs. Amplitude modulation in a circuit?

I'm trying to create two circuits that will eventually be added to a larger circuit in a custom PCB. A basic radio transmitter needs to hook into my computer via USB, and transmit data to a ...
0
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0answers
17 views

ZULU-M RF Transceiver

I am attempting to send simple ASCII characters between two RF ZuluM868 modules. It uses a Low level Rs2323 so I am using a terminal program with a USB to 3v rs232 level converter. I have followed the ...
1
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1answer
29 views

How much sensitive to thermal cycling are passive components?

One of my boards, which contain solely passive components, may be subject to high thermal cycling (up to +/-100°C, but tradeoff down to +/-30°C is possible). What sort of degradations can they ...
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2answers
89 views

configuring a DPDT switch to choose between two RF signals

I have 2 different signals coming in I wanted to be able to switch between them (choose what to transmit) using a simple DPDT switch. I have the following configuration, but I feel like I'm missing ...
0
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1answer
43 views

Class J RF Power Amplifier

What is a Class-J Amplifier configuration? Does it work in a push-pull configuration similar to an A/B? How is it physically different to an A/B? Where can I see a basic schematic? I have read ...
0
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0answers
38 views

What does KFD stand for in a N type RF Connector

A RFID antenna supplier specified the antenna connector as N-50KFD Female. After a lot of googling I was unable to determine what does the KFD stand for. Is there a standard for these letters. I ...
0
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2answers
44 views

Sending identification signal with IR or RF

Is there any way to build a device capable of sending an ID signal with IR or RF? For example, imagine I want my TV to know whose remote is being used (assuming everyone has a different remote). I ...
1
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1answer
62 views

Is CE marking on module necessary?

Suppose a RF module has passed CE EMC tests. Must the CE marking be printed on the module itself in order for the approval to be valid if it is to be used in an end product?
0
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1answer
32 views

How do you account for receiver sensitivity in tranceiver half wave dipoles?

if you are to design 2 halfwave dipoles, both can transmit to each other using 3 watts and have receiver sensitivity of -80dbm (a picowatt). Suppose they are 800m and have same height from ground. How ...
0
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0answers
45 views

PIN Diode T-R Switch for use with RF Power Amplifier

I would like to use PIN Diodes to actuate the T-R switching of my RF Power Amplifier, however, I am having trouble understanding the proper way to accomplish this. I would rather use a solid state ...
1
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1answer
51 views

Demodulation with a phase difference

This is an RF-based question. My professor told me that demodulating a TX signal that is 90 degrees out of phase with the receiver oscillator is impossible; there will be no baseband signal. He said ...
1
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1answer
62 views

Placing Ground Vias To Improve EMI

Placing ground vias all over the PCB (stiching) to improve the EMI. Have all ground vias to be spaced the same distance? Or may they be separated different distances if it is under lambda/8? I ...
4
votes
1answer
80 views

How to ensure a RF module is indeed FCC compliant as advertised?

Suppose a buyer buys RF modules from China and wants to ascertain that they're indeed FCC compliant as advertised. I'm guessing that this should be a fairly common issue since Chinese ...
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0answers
64 views

What happens if a FCC certified module isn't what it claims to be?

Suppose a radio module is already certified by the FCC but the manufacturer decides to ship inferior versions of it without acknowledging that fact, making users oblivious to the change. Do commercial ...
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3answers
493 views

What kind of metal are RF shields made of?

With the shields typically found on WiFi modules, what kind of metal are they? Are they coated? Here's an example: Thanks
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2answers
61 views

Could the metal shield on radio modules be tampered with?

I see that most radio modules have a metal shield. Is it for keeping the radio waves inside? If so, could a shield be too thick for its purpose? For instance, if one solders another piece of metal ...
0
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1answer
35 views

What is Stray Capacitance and how it can be Avoided

I have learned that especially in RF circuits stray capacitance can mess circuits up. I have learned that breadboards are a major culprit for this. However I do not know really what it is. What is ...
11
votes
2answers
625 views

Should each trace carrying RF be 50Ohm in characteristic impedance? How?

I have to translate a VHF (160MHz) receiver schematic into a PCB. After looking here and there, I am a bit confused. It seems like the main issues with RF are to avoid stray inductors and ...
0
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0answers
22 views

How to chose a right inductor for a matching circuit

I would like to chose an inductor to make a matching circuit. Operating frequency is 6.1 GHz. I am more concerned with self resonance frequency and Q of an inductor. An inductor with SRF > 7 GHz and ...
0
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0answers
26 views

Frequency separation in 2-FSK communication

I've started to post this question about the channel spacing (also called frequency spacing) and how is related to the doppler. But subsequently I've found a further possible problem, the frequecy ...
0
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1answer
78 views

Trace vs Plane on Multi-Layer Board

Designing a 4-layer board (signal+pwr, gnd, signal+pwr, gnd), and I have some newbie doubts about the best option to connect different connector's pin or IC's pad to power lines, or sometimes to ...
1
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1answer
60 views

Interfacing a GPRS chip (WISMO218) with an RF antenna. Calculating line width for the right impedance

I want to interface the WISMO218 GPRS chip with an antenna. The antenna lines on the PCB board have to be very specific, otherwise the system won't work. I have uploaded the part of the datasheet that ...
0
votes
2answers
69 views

Dipoles lengths underwater vs on land

A submarine (for example) uses a VLF communications system to remain in contact with its headquarters while submerged. The submarine drags a resonant dipole wire antenna behind it in the water. The ...
1
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1answer
35 views

connecting a GSM booster directly to a mobile device? [closed]

I live right on the edge of mobile reception. I just get a signal with an external antenna, but it is weak. I am thinking of getting a small indoors GSM booster, like this. I was wondering if it ...
0
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0answers
32 views

RF-to-DC results / simulations

Can anybody point me towards simulations of, or results to the different types of RF-to-DC implementations? As in, there are different circuits such as a basic voltage doubler, etc. to achieve this. I ...
0
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2answers
73 views

433mhz micro directional antenna design

I'm trying to build a Radio wave penetration device that register the RSSI on the RX module. There are two 433 transceivers one is the RX and the other TX - I want to place between them different ...
0
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0answers
27 views

LPRF design on 4 layers

Developing a new design on a 4-layer stack with reduced dimensions, there are some doubts I expect you can help me with. The board includes RF part, MCU, voltage regulator & battery charger. ...
0
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0answers
22 views

How do I use the XStream RF module for serial data communication with a BeagleBone Black?

I am currently part of a car team and we needed a minimum 2.5 mile range wireless system which would communicate the sensor values(Battery voltage, current etc.) to the ground station via a radio. ...
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1answer
35 views

Question about Frequency Travel Distance

I've a question regarding the Radio Spectrum and RFID which is confusing to me. From what i learnt about RFID; Low Frequency (125kHz) will have shorter range but UHF will have the longest range. ...
1
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1answer
58 views

Best approach for reverse engineering an RF Remote for a newbie

As part of a larger project, I would like to be able to replay signals of this remote. It's a remote for a temperature controller, operating at 433MHz and it looks like it's using ASK modulation. ...
1
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2answers
158 views

Explanation for: A monopole antenna must contain a resistor (or equivalent) and therefore must have 2 terminals?

Could someone explain why this sentence makes sense: A monopole antenna transfers energy from electrical domain to the electromagnetic domain, hence must contain (equivalently) a resistor, hence ...
0
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0answers
30 views

Transforming a 4-port Hybrid Coupler to a 2 port coupler

Hi So I have this one homework problem, that has been causing me a headache: If you take a 4-port 90 degree hybrid coupler and short the coupled port and isolated port, what is the resulting S-matrix ...
6
votes
2answers
234 views

When and why did 5.8 GHz become an ISM band?

It's common knowledge that the 2.4 GHz band was set aside for industrial, scientific, and medical (ISM) purposes due to its use in microwave heating. From what I've found, the United States proposed ...
0
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1answer
28 views

Conversions of radio mic receiver

Can I convert my 175.4Mhz radio microphone receiver to pick up a signal from a mobile phone?
2
votes
1answer
52 views

RF receiver design - estimate received power

I'm designing a radar receiver, whose block diagram is below: When I compute power received from radar range equation, it varies between -90 dBm to -40 dBm depending on the object's location (60 to ...
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2answers
56 views

Non-line-of-sight distance approximation between trasmitter and receiver

I have one stationary object in a 2d plane (no z-axis). Let's say this stationary sphere is in the middle of a rectangular plane. I have another object in the same rectangular plane that is in motion ...
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2answers
47 views

Antenna mounting question

Here is the datasheet and drawing of the antenna on this link I need to stick out the antenna from a thick metal enclosure, how much of the antenna should stick out? Is it 19 mm (the black rubber ...