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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.

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48 views

Is it parallel or series

In the figure below, an RLC circuit, the author in the book says, that the resonant circuit sees Rs and RL to be parallel so he combined them (R total = the parallel sum of Rs and RL), is it right ...
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17 views

Schematic diagram of a double-balanced Gilbert cell mixer

For the following gilbert cell circuit, I have few questions. I understand that R1 to R4 as well as M1 to M6 are parts of the double-balanced differential topology which helps to eliminate the DC ...
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4answers
2k views

Can I run 125kHz RF circuit on a breadboard?

I was wondering if making a low frequency RF circuit on a breadboard is viable.
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51 views

“RF energy harvesting” Can rf transmitter be a rf signal generator?

I'm trying to build an rf energy harvester. But having some problem. The harvester should collect the 915Mhz signal. Can I use 915Mhz rf transceiver + 915mhz amplifier as the rf signal source? How ...
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1answer
87 views

Alternative wireless technology for passive RFID tags

I am working on a project where I have 3 boxes and a RFID reader (mfrc522) attached at the bottom of each box. I keep my wallet/keys/etc in these boxes and a LCD screen displays what is in each box ...
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3answers
141 views

How to find the frequency of any device?

Are there devices which can figure out at what frequency every device transmitting radio frequencies operate at precisely? Say from a high of 2.4 GHz microwave to a low of 402 Hz pacemaker.
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0answers
11 views

Single Ended DAC to Differential Input Modulator

I'm trying to drive a differential input IQ modulator (LT5571) with a single ended DAC (MCP4912) for modulation of a narrow band signal (~10kHz max). Because of the nature of the low frequency ...
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0answers
49 views

What transmissions technology has the largest range, with the lowest power consumption? [on hold]

Perhaps this isn't the right question (or right place to ask it) but I am building a fixed wing "drone" and I would love at least 1 way communication (from the drone to a station) for the majority of ...
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3answers
10k views

What is a PA/LNA?

I saw a comparison of two similar radio receiver modules. They used the same IC, but one had a greater range due to the inclusion of a "PA/LNA" which I understand to be an abbreviation for "Power Amp /...
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1answer
91 views

BLE and Bluetooth Classic Coexistence?

we are designing a fairly compact PCB for a communications device. We are looking at using BLE as a link for voice to a separate microphone, and BT Classic to be paired with a smartphone. We are using ...
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0answers
32 views

Pair 433 MHz RF devices [on hold]

I need to build system "turn on lamp with wireless PIR sensor". I'm planning to buy 433 MHz PIR sensor and somehow pair it with 433 MHz relay. But how to pair them? How to get codes from transmitter ...
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2answers
73 views

Smith chart of λ/4 Transmission Line

I came across the following slide on power combiner circuit and I have questions about it. Why traverse across the upper half circle ? Why "ZT-line is the geometric mean of Zout and Zin." ?
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1answer
31 views

Cutoff or Corner Frequency for Coax Cable

I'm trying to understand better what the significance of the cutoff frequency for coax cables is. I have a case where a cable is considered for use at frequencies up to 3% higher than the manufacturer'...
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1answer
56 views

In actual OFDM trasmitter, is the stepwise waveform after IFFT put on the carrier as it is?

I simulated OFDM on MATLAB,though,the spectrum of it is not white(flat shape). Why? IFFT circuit of actual transmitter uses higher IFFT order than the count of subcarriers? P.S. I simulated with the ...
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0answers
24 views

RF device connection issue

I have a surface acoustic wave based separator device built on piezoelectric (PZT) substrate and this is mounted on a PCB for the external connection as you can see from the picture. When I was ...
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1answer
87 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 ...
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1answer
94 views

Through Hole (Vertically Mounted) SMA Connector on PCB - Feasible for GNSS Application?

Due to space constraints on a board I am designing, it is ideal to have the GNSS cable connecting vertically onto the top of the board. I haven't been able to find any edge-mounted connectors that go ...
2
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0answers
48 views

Audio PWM over Radio [on hold]

I'm working on a project in which I must send audio over RF such that remote speakers can pick up the signal around a house/apartment. The goal is to broadcast music from a single device somewhere in ...
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0answers
91 views

First PCB project design critique requested (RF) EDITED

This is my first ever RF PCB project and it'd be great to receive some guidance to make this project 'first-time-right'. It's purpose is to transmit and receive signals at two different frequencies: ...
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2answers
89 views

Which remote communcation type should I use?

In my project I have to give only 4-digit number to each device(50+ devices) without any wire. And there will be only one transmitter for all receivers. Which communcation type should I use? ...
0
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1answer
82 views

Compatibility between XBEE-PRO 900 HP and XBEE SX

I wanted to use a 900 MHz xbee and I need one side to be surface mount. So I'm thinking of getting an XBEE PRO 900 HP (XBP9B-DMST-002) and an XBEE SX (XB9X-DMUS-001). These devices have the same ...
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0answers
17 views

EN 300 328 Receiver (RX) Blocking | BLE DTM Implementation with Signaling Analyzers?

We are working through a Nordic NRF 52832 certification, and are getting the device CE tested. We are running into some issues getting our device connected to the R&S CMW 500 signaling analyzer ...
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2answers
78 views

How same frequency signal with different power are produced?

My router have settings to configure transmission power and as i know energy of a signal is given by $$ E = h\nu $$ where \$E\$ is the energy of the signal, \$h\$ is Planck's constant, \$\nu\$ is ...
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1answer
53 views

designing Low-Pass Transmission Line Stub Filter

I'm trying to design a Low-Pass transmission line stub filter, and I have a few question regarding it. I'm rather new to RF-circuit design, so please bear with me. If my desired specs include the ...
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0answers
50 views

Is there any 433mhz rf transmiter/module/transceiver can work at 1v voltage or lower? [closed]

I am finding this kind of transmitter but it seems there is no such kind of components. Does anybody know? Thanks Because I want to use a msp430l092 which work can at 0.9v at least. Combining it ...
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2answers
1k views

Expanding range of RF sender (FS1000)

I send signals using the FS1000A, i.e. 433MHz. The module has a pin named "ANT", where I can solder an antenna, like a short piece of wire. As the sender's range is not that far, I want to increase ...
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0answers
20 views

Realizing a prototype filter in ADS or any other simulator

I'm trying to design a stub-filter, and I'm stuck on realizing the filter design using Richard's transformations and Kuroda identities. I'm building a 5th order Chebyshev LP-filter for 2.6 GHz pass-...
2
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1answer
43 views

What should be assumed regarding the upper frequency of sma connectors

There are infinitely many sellers of sma connectors of various kind in ebay or other stores. This one is an example. But they very seldom specify what is the maximum frequency at which the device can ...
3
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0answers
41 views

Microphonic SAW transmitter?

I built this very simple SAW transmitter, with a simple "spring" antenna for the right frequency. To test it, I tuned a portable receiver to around 433.92Mhz and fine tuned it until I heard silence. ...
0
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0answers
25 views

Need guidelines with creating chip module footprint [closed]

I am trying to design my own RF PCB using online pcb-editor Easyeda. My circuit uses RF module cc1101. I couldn't find matching PCB library for my module so I decided to create one myself. I basically ...
0
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1answer
72 views

SNR wall definition

I want to ask you if my understanding of the definition of the so called "SNR wall" is correct and complete. The SNR wall phenomenon is described here and here. If one has further information that ...
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2answers
70 views

Half-duplex wireless: Is a tuned antenna more important for the transmitter or the receiver?

I intend for this to be a general/conceptual question that could apply to any wireless communication hardware, however I will use a specific example to talk about. Let's consider the nRF24L01. (...
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4answers
703 views

How to make a RF additive mixer for two inputs in same frequency band?

One of the most common designs for a SSB modulator (phase shift method) involves an additive mixer as the very last stage. Here is a block diagram for reference: This additive mixer must provide ...
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2answers
191 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 \...
2
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1answer
94 views

Does the feed line contribute to the function of a PCB patch antenna?

First let's make sure I've got my terminology right. The following are both 2.4GHz antenna: The first is a simple coaxial antenna that's just cut to the appropriate length for the relevant ...
0
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0answers
31 views

Reactance of a dipole antenna

I am interested in calculating the input impedance \$Z_{in}=R_{in}+jX_{in}\$ of a dipole antenna numerically. However, I am unsure how I would compute the imaginary part of the impedance (\$X_{in}\$). ...
1
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1answer
90 views

Sequencing modes for FCC “Intentional Radiator” test

I'm FCC certifying as an "intentional radiator" a product that uses a custom antenna and off the shelf Broadcom WiFi module. The module has an antenna port, so single-modular and limited single-...
0
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1answer
102 views

Using a p channel mosfet to switch a RF switch

I'm very new to electronics, i have the following RF switch (CG2179M2) which i need to control using the output signal of my MCU, which will provide a 3.3V HIGH for transmit mode and LOW for ...
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0answers
39 views

What kind of Modulation? Who transmits on 850 MHz (LTE-Uplink or GPRS?)?

Hey, I found an interesting Signal on 850MHz (in Germany). It is not symmetric and very strong (relative to many others due to bad antennas). On the right side the bandwith is permanently used, on the ...
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1answer
17 views

Conversion Gain Definition for DSB-SC Upconversion

If I multiply a baseband signal \$A cos(C\omega t)\$ and a carrier signal \$B cos(D\omega t)\$, the result is \$\frac{AB}{2} [cos(C-D)\omega t+cos(C+D)\omega t]\$, which is a double sideband, ...
0
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1answer
32 views

I cannot find information about some chips in 3 stage LNA circuit

Hi, here you can see 3-stage LNA circuit. I want to know information about two chips(6 pins) with R8 mark at the top. Also, 4 chips with D4 mark with 3 pins at right side. Is there anyone who has a ...
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0answers
28 views

Cheap RF 433.92MHz design, PCB track antenna [duplicate]

I'm doing a RF remote control project using a PCB with microcontroller and with simple onboard antenna layout as transmitter and a 433.92MHz receiver RWS-371F-6 model. Here is the datasheet of the ...
0
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1answer
97 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 ...
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1answer
100 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 ...
0
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1answer
65 views

How can I design a high speed RF peak detector?

The diode-capacitor solution would not work in my application because the operating frequency of my circuit is about 1.4GHz. So what is an alternative solution that would work in such high frequencies?...
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1answer
90 views

High-voltage (HV) messing with my transimpedance amplifier circuit

I have a transimpedance amplifier circuit that takes 100kHz small current and gives the voltage output proportional to current amplitude. Everything works properly when nearby HV circuit is off. When ...
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2answers
112 views

160MHz Ambient Office Noise?

I've got a shielded tent in our office and I see one ambient element I don't have a good explanation for. We see some ambient noise at 700MHz - 800MHz which I guess is cell-band noise. But there is ...
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0answers
103 views

On purpose shorted capacitor in schematic

I've come across this schematic from an RF device where I've spotted some weird configuration of capacitors. There are, all around the schematic, some shorted capacitors which I can't figure out what ...
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2answers
116 views

Tube transmitter tuning

I am trying to tune/tweak/repair this transmitter for a friend of mine. It is oscillating, and it has rf power on the antenna, but it just doesn't seem as "strong" as it should be. The diagram says ...
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1answer
110 views

A beginner that could use a few tips on wiring my first circuit involving relays

I am in no way experienced or knowledgeable with circuits or electronics passed installing my own car subwoofers and amps, or swapping out pickups on a guitar which means I only basically know how to ...