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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41 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 ...
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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
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2answers
499 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 ...
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0answers
20 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 ...
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0answers
24 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 ...
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1answer
60 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 ...
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1answer
36 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 ...
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1answer
48 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 ...
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1answer
29 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 ...
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0answers
31 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 ...
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2answers
37 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 ...
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0answers
24 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. ...
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0answers
11 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
34 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. ...
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1answer
51 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. ...
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2answers
142 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 ...
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0answers
25 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 ...
4
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2answers
93 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 ...
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1answer
27 views

Conversions of radio mic receiver

Can I convert my 175.4Mhz radio microphone receiver to pick up a signal from a mobile phone?
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1answer
46 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
53 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
41 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 ...
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1answer
55 views

Using of RF transcieivers to communicate over 230VAC powerline

Initially I need to communicate between several devices placed within one appartment (or a building). All those devices will be connected to 230 VAC power line. I'd like to skip any wireless ...
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1answer
58 views

How deep can I bury a 1 MHz transmitter

So in designing a deep underground sensor network, my team wants to use a 1 MHz radio, but we cannot determine a way to model the soil, so as to calculate how deep i can bury a radio for showing proof ...
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1answer
57 views

how to make an rf choke ? & tx rx coils

i am an tinkerer and trying to make an wireless charger in which i felt difficulty in making an RF choke coil of 8.6uH , 0.674uH & 1.235uH so any can please help me out ...
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0answers
22 views

Does higher clock speed equate to higher resolution of distance measurement using RF?

I am trying to create a simple measurement system using RF but have found only devices that have fairly large windows of accuracy (+/- 1ft is the best one I've found yet). If I want to measure the ...
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2answers
67 views

Electronic compass, RF and batteries

I am currently working with a project where i am creating a small embedded board consisting of a 9DoF IMU which is transmitting its data with RF (BLE or normal RF). Furthermore there will be a battery ...
2
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2answers
105 views

How can I best fake an (AM radio) antenna signal?

I have an old (~late 1920s) AM radio that I'm currently working on. As I don't want to modify any of the internals significantly, it would be nice to have a way to fake antenna input. It's not ...
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1answer
58 views

receiving transmissions transmitted on different channels sub-1 GHz using one receiver

I am using a RF development board along with a CC1120 RF modulator + CC1190 amplifier on carrier frequency 868MHz, RX filter bandwidth 25KHz, modulation format 2-FSK, 1.2Kbps bit rate, 10dBm output ...
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0answers
24 views

Achieving multiple transmissions at the same time within a Sub-1 node network

I am using a RF development board along with a CC1120 RF modulator + CC1190 amplifier on carrier frequency 868MHz, RX filter bandwidth 25KHz, modulation format 2-FSK, 1.2Kbps bit rate, 10dBm output ...
0
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0answers
20 views

RF Propagation of a beacon placed in a narrow hallway

If the walls are sufficiently thick concrete which have very high attenuation, and if the red circle is a beacon/ibeacon with an omni antenna, what is the expected propagation pattern? I want to ...
0
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1answer
29 views

Microstrip lenght problem

I'm simulating a single microstrip half-wave resonator (1.8 GHz) in Sonnet and using ADS LineCalc tool for calculating the microstrip length but I'm getting a wrong number. Substrate parameters ...
1
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2answers
40 views

Will an impedance matching network also act as a filter?

Will a matching impedance network also act as a filter? I'm using a pi network and am wondering if I should also add a filter. I designed the pi network by using the program SimSmith and it consists ...
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2answers
46 views

Band Pass Filters for MHz

I have come across the following site: Passive Band Pass Filter - Electronics Tutorials. It is a tutorial about band passive filter circuits. The following formular is given with: $$ C=\frac{1}{2 ...
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0answers
49 views

Lc tank resonator vs. quartz crystal?

For Colpitts and Hartley oscillators, which is preferable to use: an lc tank resonator, or a quartz crystal? I've built Colpitts oscillators with both an lc tank circuit resonator, and with a quartz ...
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0answers
69 views

tunable oscillator circuit: get rid of the variable capacitor

In these days I'm doing some experiments with oscillators circuits; I've built an oscillator circuit which is tunable using a variable capacitor (the range in picofarad of this variable capacitor is ...
0
votes
1answer
60 views

How to convert this FM transmitter to receiver?

I made this circuit and it works properly but I need to make an FM receiver using the same idea of this circuit (common base). Would you tell me what changes should I make so that the circuit is able ...
5
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7answers
822 views

Is the meaning of a Decibel different when applied to Voltage vs Watts?

If I have an amplifier that provides +3dB, or an attenuator that provides -20dB, then how do I know if that applies to Voltage or power? In other words, if I have a 0dBV signal and I run it though a ...
0
votes
2answers
51 views

Circuit board layout: wifi ceramic antenna next to a electromechanical relay

Is it okay to place a small ceramic antenna not far from a electromechanical relay? Would the magnetic field generated by the relay coil (when on) affect wifi operation? clarifying edit: not far = ~1 ...
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1answer
77 views

Boost a weak AM transmitter

I've made this simple AM transmitter: http://makerf.com/posts/fun_with_crystal_oscillators_part_3 The author of this circuit, claims that would be possible to extend the range of this transmitter ...
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2answers
71 views

Design options for a simple AVR (Arduino) based RF communication system

I am trying to build an AVR based, RF service calling system. It works like this: someone at the transmitter presses a button and the guy at the receiver get notified with the ID of the transmitter ...
0
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0answers
29 views

occupant sensor/detector for goods vehicles - active during driving

I need to detect and raise an alarm in the goods load area of a consumer goods vehicle if there is human movement detected whilst the vehicle is in motion. To put it simply - our goods vehicles are ...
0
votes
1answer
24 views

wireless sensor baud rate calculation

I need to calculate baud rate of wireless sensor which operates on 433.92Mhz and uses OOK modulation. Signal wave form and packet structure are known. Packet = 36bit (44.7ms), each bit consists of 2 ...
2
votes
1answer
54 views

Calculating expected receive power

I am using a TI CC1120 + CC1190 combination to transmit data wirelessly using Sub 1 GHz link. My output power is about 27dBm according to the CC1190 SOC. I want to determine the maximum power (an ...
0
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0answers
5 views

How to add Marker (Event) to a bitstream file in Agielnt MXG Signal Generator?

Using an Agilent N5182B MXG Vector Signal Generator in the Dual ARB mode I am able to create, download and play a baseband waveform with the samples' marker #1 set, and sensed via the ...
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0answers
109 views

Pic to Pic Communication with 434mhz wireless module?

I want to transmit Data From one Pic18f2550 to Another using a cheap 434mhz wireless module. but its not working at all. Following are the circuits for Tx and Rx respectively. the code for Tx ...
2
votes
1answer
41 views

Will a CC1120 IC be burnt during transmission if antenna is removed

I am using a TI CC1120 evaluation kit which is working in the 800MHz band amplified by a C1190 to a 27dBm output power. I would like to know if it would damage the board to be used with no antenna ...
1
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1answer
72 views

Why are shorter leads preferred over longer leads?

I'm building oscillator circuits on a copper plate for an RF design class using the dead-bug method. I know that short leads between components is preferred over long leads, but why is this? I heard ...
3
votes
1answer
57 views

How do I find spectral purity?

How is spectral purity measured? or evaluated? I have this signal coming from a 10 MHz crystal oscillator. I know how to calculate the SNR, but how do I calculate the spectral purity? Is it also a ...
2
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2answers
283 views

Why does a metal sheet block all noise, but not when wrapped around a cable?

If I place a flat sheet of aluminum foil between a near-field probe and a noisy wire, the sheet completely blocks the noise. However, if that sheet is then wrapped around the wire, it seems to have no ...