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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Characterization of Power Harvester

I have chosen a power harvester to power a few things as part of a wireless system. This one is the one I have and it seems to be operational: http://www.powercastco.com/PDF/P2110-datasheet.pdf ...
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8 views

6LoWPAN deployment in an MCU

I need design a 6LoWPAN supported node using a TI CC1120 controlled by a TI ARM Cortex M4 TIVA 123 Lanchpad. I require to run TCP, IPV6 along with 6LoWPAN in the Lanchpad connected to the CC1120. I ...
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53 views

Why deliberately mismatch impedances in RF?

My professor wants me to design a cascaded RF amplifier, with mismatched stages. The reasoning is to increase bandwidth. Is this correct? If so, can anyone elaborate on the theory why mismatching ...
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1answer
74 views

Why don't we use cascoding in RF amplifiers?

I need to design an RF amplifier with high gain. It seems every RF book teaches cascading, but not cascoding. Is there a disadvantage to cascoding? It seems like we don't need to match impedances with ...
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43 views

How to conduct “Transient Power” measurement according to ETSI EN 300 220-1 (v2.4.1)?

Background Info The company I work for builds Active RFID hardware that needs to conform to the regulations defined in ETSI EN 300 220 (Part 1). Our working frequency is 433.92 MHz. I am responsible ...
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1answer
47 views

Hartley Oscillator Alternate Oscillation Mode

I've been trying to build a hartley oscillator and have almost succeeded, however my calculations are off by appx 1000 relative to the measured waveform. AND the kicker is that it only works when I ...
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18 views

Searching RF Wideband Downconverter [on hold]

Like the title already states, I am searching an RF Downconverter for a range between 250MHz and 5GHz. I would like to use the converter for several projects I am working on. Among them I would like ...
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54 views

How to improve FM radio reception [on hold]

I have a Pioneer HiFi amplifier+tuner but the FM radio reception is very poor, probably because I don't have the antenna cable anymore to plug here (see image below). (But I also remember that when I ...
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20 views

IEEE 802.15.4 standerd

According to Wikipedia the said standard defines physical layer and media access control (MAC) control for devices working in the Sub-1 range. However I noted that this standard is not similar to ...
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34 views

Colpitts vs. Hartley?

What are the pros and cons of using a Colpitts or a Hartley configuration for an oscillator?I know that the difference between them is the form of feedback, but does one or the other perform better ...
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20 views

How to measure the QoS of an anlog wireless link

I am working with FSK transmitter and modulator on the 433 MHz band, I am wondering how can I measure the QoS of the resultant link given that The receiver reports the received analog data only with ...
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1answer
34 views

2.4GHz Bluetooth PCB Trace Antenna Range

I have designed a PCB trace antenna for a BLE module. I used an existing reference design, which is offered to be used in your own design. I am able to connect to the radio, and on a spectrum analyzer ...
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3answers
49 views

Efficiency of Antennas vs operating frequency

I have refereed a document from TI which mentions that antenna efficiency decreases as frequency is further decreased. Although 136 - 240 MHz has highest range for equal power, the efficiency of ...
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3answers
86 views

Sending data from 4 transmitters to 1 receiver without a microcontroller

I am working on a project to wirelessly check whether any of four switches are pressed and I don't want to use a microcontroller on the transmitter side. I have worked with the cheap 434MHz HT12E/D ...
5
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2answers
220 views

Frequency spacing and the doppler effect

Suppose that I'm working on a system which needs to use a transceiver with an FM signal. If that system moves very fast (i.e. it is a satellite or whatever) in which the maximum doppler effect can be ...
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2answers
31 views

Uneven (10 dB) RF Power Splitter/Combiner

I'm trying to modifying and improve the MIT radar project Here's the basic block diagram: Input power is split by 3 dB SPLTR1 to transmitting antenna and LO input to the mixer. From what I ...
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1answer
16 views

Analysing performance of Sub-1 GHz 433 Band

I am required to analyse the performance of my 6LOWpan network working on Sub-1 400MHz band for criteria such as throughput, range, packet delay, PER etc. My system uses CC1125 (Sub-1 modulator) + ...
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1answer
61 views

13MHz ISM band vs 433MHz ISM band

Would 14 MHz ISM Worldwide band have superior range and penetration (equal tx power)capability than the 433 MHz band? In that case, why aren't any transceivers made for this band? My application is ...
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40 views

Sub-1 GHz Narrow Band vs Wide Band

As per the TI document I came across which compares narrow band sub-1 usage vs wide band sub-1 usage mentions a concept called coding gain and its disadvantages. Because of my lack of understanding ...
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1answer
41 views

Assembling my own antenna cable - considerations

I need to use a 4 m antenna cable on an application. Due to non-standard cable length and some more unrelated reasons, I am considering to assemble my own cable which I have not done such thing ...
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1answer
42 views

Sending On/Off signal through RF

I want to have one circuit generate a radio frequency and have another circuit act on the presence of that radio wave, to turn a transistor ON and light up a LED for example. Just a simple as that, I ...
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23 views

Problem with damanged radio transceiver

I'm developing a 2.4Ghz mesh and I've a problem with MRF24J40MC transceivers being damaged. The exact issue is that the transceiver can't receive incoming data unless the transmitter is very close, ...
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1answer
38 views

Where to get PSPICE models of ceramic resonators?

I wish to design and simulate IF filters using ceramic resonators and crystal oscillators in OrCAD Capture or LT SPICE. The default libraries don't have any ceramics, so anyone know where to download ...
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1answer
36 views

multiband antenna for RF

I'd like to make a small chip using either the Texas Instruments CC1101 or the Nordic nrf9e5 that provides a range of different frequencies. This is mostly meant to be a tool for playing around at my ...
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1answer
28 views

Wifi Channel vs a Sub 1 GHz channel of same width

If the same channel-width is allocated for a WiFi channel and also for a Sub-1 GHz channel, would the maximum allowable speed be the same for both channels theoretically? If they differ, what is the ...
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3answers
103 views

least GSM power in dBm required to send an SMS

I deploy an application in the forest using an M2M module (SIM968). I have read through its datasheet but I am not able to find out what is the least GSM power that should be incident inside the ...
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1answer
58 views

RSSI measurements near wifi router

I have a question about RSSI and EIRP. When I bring my smartphone very near my antenna wifi router (+20 dBm EIRP) the analyzer wifi application shows me an RSSI level about -20 to -25 dBm (a negative ...
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1answer
64 views

channel seperated communication in RF

In RF communication the carriers such as 950MHz, 133MHz are available under 1 GHz. If there are 50 devices using the for example 433MHz carrier, then how could large number of devices talk to each ...
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41 views

Sub 1GHz 433-MHz Band simultaneous channel usage

I live in Asia and I intend to use the Sub 1 GHz 433-MHz Band for a project. Before I proceed I wish to state I am using a combination of TI products CC1120 with a CC1190 to achieve more range. ...
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1answer
34 views

Buffer between high pass and low pass filter when making a bandpass filter?

For a passive filter stage, I want to combine a high pass filter with a low pass filter to create a bandbass filter. Can I just make a simple RC circuit for each and connect them together? Or would we ...
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1answer
60 views

Should I use a passive or an active filter?

simulate this circuit – Schematic created using CircuitLab I need to design an am receiver as a project. On the front end I have three modules; BPF1 the "roofing filter" or the ...
2
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1answer
51 views

Wires acting as input and Output

I always wondered how ear phone wires acted as antenna giving input to the connected device and also acted as the output driving speakers... Does the the frequency of these has to do something with ...
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2answers
104 views

What RF attentuator would be used for the HackRF?

Background info: The HackRF is an SDR Radio capable of receiving and transmitting frequencies from 10MHz to 6GHz. Michael Mossmann, the creator of the HackRF, states in his wiki that: The ...
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1answer
61 views

XY-MK-5V suddenly stops working

I have a situation that just baffles me here... I bought these cheap XY-MK-5V RF receivers with FS1000A transmitters. I fitted the receiver to an Arduino UNO connected to an 8-channel relay board, ...
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1answer
113 views

How does a low power device make a direct uplink to iridium satellite?

I was always fascinated by this idea. You are literally able to communicate or open a web browser from anywhere in the world. I am OK with the low power device able to receive data from satellites, ...
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34 views

One Transmitter for multiple recievers

I need to track case pans at work, I would like to do so by using cheap 433Mhz receivers. My problem is we have up to six hundred case pans in the building at any given time. Will I be able to use one ...
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1answer
54 views

why is the ic rf shielding exposed

I assume this rectangle around the IC is for RF shielding, but why when is it exposed? I have seen this occasionally and I am not sure of it's exact purpose or why its exposed. Googling the title ...
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1answer
30 views

Problem in a receiver circuit

I have following circuits : Rf Amplifier : Mixer : The amplifier is able to give me a good gain of around 200 to 300 for signals in 100 MHz range. The mixer, which follows the amplifier, is ...
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1answer
45 views

impedance matching single vs series capacitor

Im looking at a impedance matching circuit on a schematic that shows a .75pF capacitor pulled to ground. With my current board design I have a 1pF and a 3.3pF on the board already so I am thinking ...
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2answers
99 views

I can not receive radio waves using LM386?

I've made two different circuits to receive RF using LM386 but they doesn't work. I've changed the values of C2 and L1 to change the frequency. I've also changed the gain but nothing happens. The ...
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3answers
3k views

How can over 24 GHz communication be possible?

I read the article Google wants the US' wireless spectrum for balloon-based Internet. It says to use over 24 GHz frequency spectrum for communication. Is it ever possible to generate that high ...
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2answers
64 views

Why there is many configurations of Colpitts oscillator?

I would like to understand how colpitt's oscillator works but I'm confused because there are many configurations on the internet and I don't know what is the difference between them. For the next two ...
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1answer
62 views

RF sources location system

At my workplace we have to monitor devices that operate at 433 and 869 MHz, but lately there's an area that for some reason has a transmitter, that isn't ours, jamming the communications. The signal ...
2
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1answer
76 views

High Power RF Detector Circuit [closed]

I was tasked to work on an 'RF Detector Circuit' for work. The circuit has an input RF power of 72 Watts at a 7.5GHz frequency through an 8mm wire. It's supposes to reduce that power and voltage, and ...
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19 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
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1answer
81 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 ...
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1answer
50 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 ...
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1answer
56 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 ...
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3answers
366 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 ...
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1answer
91 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?".