Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g. TV or radio) waves. -Wikipedia

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35 views

RFID reading / sniffing demonstration at a live-event

In the context of a live-event, we want to demonstrate how easy it is for someone with the right equipment to sniff RFID devices, including clear-text information. Our idea is to hide a RFID reader ...
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1answer
39 views

What components do I need to connect a phone to my device via Bluetooth?

I have a phone I want to connect to a docking station I am making, via Bluetooth for as cheap as possible. As I understand the situation, all I need is something that can pick up a bluetooth signal ...
1
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1answer
53 views

Determine the working frequency band of unknown RFID chip

I have a passive RFID chip from which I would like to scan the ID. I have a standard USB RFID Reader, but this doesnt print out anything. This reader scans the 120–150 kHz range, so the chip must ...
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1answer
37 views

Passive RFID transponder timing system

I'm looking to build a timing system base on passive RFID transponder. This is how I see it : An antenna to "question" the tag An antenna to receive tag unique ID A tag with unique ID I would like ...
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1answer
38 views

Radio direction finding - dependence on source signal type

I want to make a robot that can track the direction of the transmitter that is controlling it, for example to aim a camera at the transmitter. The robot vehicle will be controlled by a 2.4ghz ...
6
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0answers
91 views

Antenna matching network topology

In tuning an antenna, there are multiple possible topologies that will take it to the middle of the smith chart. Some differences that I can see between them are: Component ESR (losses). Effect ...
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0answers
40 views

Understanding the tradeoffs between UHF and Bluetooth in Remote Keyless Entry

I've been doing some research on remote keyless entry, and I am wondering why Smart Keys and the like use UHF in key fobs, instead of Bluetooth Low Energy? Is it because BLE has only been a round a ...
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1answer
35 views

Effect of antenna position indoor and influence of multipath

for my current project I do research regarding indoor-localization and I try to use the RSSI from my wifi to calculate the distance between smartphone and access point. I heared that: ) this ...
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1answer
57 views

Impedance matching with unknown load

I somewhat know the answer to this question but just want to clarify. In order to design the impedance matching, I will need to know the load impedance and the source impedance to begin with. ...
3
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1answer
72 views

What exactly is (Horn) Antenna Gain

I was doing an experiment for finding the radiation pattern of Pyramidal Horn Antennas at RF frequencies(as part of my course curriculum). There I came across the Friis Transmission Equation What ...
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2answers
87 views

How can I turn pulsating DC (square wave) from a 555 IC timer into an ac square wave?

I am trying to create build a morse code transmitter. I know that morse code is sent at 500 KHZ so I set my 555 to spit out pulsating DC in a square wave with 9 volt peaks. But I am unsure wether ...
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4answers
55 views

GPS Antenna Selector: How to electronically select one antenna from multiple available antennas?

I want to connect multiple GPS antennas to a single GPS module and select one of them based on some logic. Basically, I want the module to receive signals from only the selected antenna. Is there an ...
0
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1answer
42 views

How to install an embedded GPS patch antenna

How should I install an embedded GPS antenna? Here is the antenna in question: http://www.robotshop.com/ca/en/seeedstudio-embedded-gps-antenna-for-gps-bee.html It has a 9 cm cable. My project ...
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1answer
79 views

Antenna Diversity: two Yagi antennas to the Rx and Rx/Tx u.fl-male points on the wifi-NIC?

I looked at the BCM4312 file - available as as doc or a pdf - and it says: BCM4312 has 2 radio chains, one is a dedicated Rx chain, the other is shared by TX and > RX chain using an RF switch ...
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2answers
70 views

RF Energy Harvesting Project

I am presently working on an energy harvesting system using RF signals. I have read some of the other posts made on this topic and have learnt quite a few things. However, I have some questions that I ...
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0answers
66 views

What kind of antenna is this?

The product page for this antenna supplies meager information. Do any of you RF gurus have a guess what kind of antenna this is as well as any other insight or reference radiation patterns?
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1answer
31 views

Multi-antenna extension for NFC

Like many, I am new to this. I am working on a project that would require a short read range over a covered space, like a person's body or table top. Could I make an extended antenna from my smart ...
3
votes
2answers
218 views

AM and FM reception with the same antenna

I'm designing a radio with the Si4735 chip to use in a car, and I want to use the existing FM antenna for both FM and AM reception. I'm not sure how to go about this, exactly. How would I go about ...
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1answer
61 views

Improving reception of 318MHZ remote control

We have a gate opener with keyfob-type RF remote transmitters that operate at 318MHZ. The range from inside the car is about 75 feet -- less than we'd like due to the time taken by the gate ...
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1answer
59 views

Separate antenna for radio transmitter and receiver

I am building a HAM radio. Do I need a separate antenna for transmitter and receiver? I will be using 20m band and voice communication (No Morse code). My primary requirement is that I should be able ...
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2answers
59 views

What are evanescent fields?

I am not able to understand what is the origin of the evanescent field, how do they interact and what is the physics behind it.
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2answers
81 views

SNR vs Signal Strength for digital throughput

I'm trying to compare two antennas, A and B for WiFi. A is showing: Signal Strength of -77dBm, but SNR of 9dB. B is showing: ...
0
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2answers
167 views

What is the difference between peak-power, average power and true RMS power in RF measurement?

What difference between peak-power, average power and true RMS power in RF measurement? I have read a peak-power measurement can calculate average power measurement also. Does any of these needs ...
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2answers
91 views

What power is measured by a spectrum analyzer?

Is the signal level that is shown in a spectrum analyzer power of the signal being measured. If yes then what power is it: average power, true power or peak power? Also when using a power meter for ...
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0answers
41 views

Determine current so that you have circular polarization

I have a problem in resolving the first point of exercise on antennas. Note: if it wasn't clear \$\phi_1\$ and \$\phi_2\$ are phase of alternate currents \$I_1\$ and \$I_2\$ I know that to have a ...
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1answer
88 views

How does square metal plate antenna work?

I have a GPS receiver(works at 1575.42 MHz) with chip-antenna: As I understand, this metal square plate is an antenna which is connected to PCB with short 5-6mm metal rod. This metal rod is hidden ...
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1answer
77 views

What signal will come in?

I have a simple setup as shown, I would like to know what kind of RF signal will come in? Since the filter is configured around 2.4GHz, will all ISM (WiFi, Bluetooth, Zigbee, etc.) come in? The ...
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1answer
66 views

Patch Antenna Inset Feed Past Exam Question

I'm trying to work out what 3.d) is meant to be. I'm not entirely sure which part of the antenna it is referring to; I assume it's referring to width of the gap between the feed and the patch. If ...
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0answers
57 views

How to calculate Input backoff per carrier of a satellite

I was trying to calculate the sizing of SSPA in my satcom network where input backoff per carrier is required to calculate Power flux density. My current network configuration in C band is Total ...
6
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1answer
145 views

A poor man's alternative to a network analizer for antenna matching

I'm doing a small board with a 915 MHz transceiver. A small helical antenna is used, which is located on board with a very short path (10 mm) from the IC, including balun and a matching network. There ...
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0answers
46 views

ADC and Pre-Amp Suggestion for RBpi

I want to receive VLF signals (between 15kHz to 30kHz) with my RBPI. So I can found only this antenna: Miniature Very Low Frequency Antenna ANTM1. This miniature 6 inch long antenna can be ...
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0answers
79 views

The BLE antenna make my CC2541 chip broken?

I design a BLE board for transfer data, In the beginning, I can burn the program into the CC2541, and work well. But, when I transfer the data about few minutes the CC2541 was broken, and the ...
3
votes
1answer
134 views

Antenna matching network. What? Why? How?

I'm designing a small board featuring a transmitter in the 900 MHz band. Since RF is definitely not my strongest subject, I'm basically trying to follow all the datasheet recomendations regarding ...
3
votes
2answers
135 views

How does this antenna match work?

I had a matching technique described to me by a professional broadcast engineer. Here's the problem: you have a vertical antenna with a low resonant impedance1, let's say \$38\Omega\$, but you need a ...
6
votes
2answers
224 views

How does this quartz antenna work?

I picked up something called a quartz antenna at a surplus store for $2.75 so I could tear it apart. This is what I found: There were two small cardboard boxes filled with loose quartz crystals ...
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1answer
61 views

Good book/reference for electromagnetism and distributed elements model

I am looking for a good explanation of what is in "between" of Maxwell's equations and the lumped model. I am talking specifically of RF electronics and the distributed elements model. I am ...
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1answer
113 views

Connect VLF antenna to raspberryPi

I want to connect two VLF antenna (given below) to a RaspberryPi using it's GPIO ports with a MPC3008 ADC. Desired frequency range is between 3kHz to 30kHz, and MPC3008 supports 200,000 samples/sec ...
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2answers
290 views

Does the orientation of a Bluetooth antenna affect the transmission distance?

I'm doing a project with a Bluetooth device for the first time, specifically with a JY-MCU Bluetooth module: As you can see, the antenna is on the green PCB, which is in turn soldered to a breakout ...
1
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0answers
42 views

MIPI RFFE software implementation

I'm currently trying to implement the MIPI RFFE (As master) protocol on a simple AVR microcontroller, the specs says that the clock frequency can go down to 32 kHz, so I guess this it should be ...
2
votes
4answers
114 views

“If an antenna can transmit, it can usually receive as just as well”

Scenarios So, I set up an induction loop, just a simple single wire loop around a house with a little pickup coil for picking up the loop audio. Lets say I want to run this in REVERSE I have heard ...
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2answers
65 views

Antenna gain of cell tower

I am doing the link budget for a device several hundred meters away from the typical cell tower. I have already found out how much antenna gain for that device. I am wondering how much antenna gain ...
0
votes
1answer
110 views

RF: what are some sources that are transmitting few hundred of watts signal power?

I am looking for some source (TV broadcasting station, or cellular tower,etc) that transmit a few hundred watts of power. (Just typically please). Please give me some idea to get me started so I can ...
1
vote
1answer
59 views

Antenna: RF, need help

I am trying to find a path loss model for "wireless sensor network". More specifically, I am looking for model for Cellular tower 100~1000MHz) and (60~600W) as transmitter and a small wireless sensor ...
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3answers
94 views

Bluetooth general question about antenna

I want to ask you about Bluetooth antennas. I saw that some modules like HC-07 have a zig zag antenna on them: And others like BTM-331 do not have such an antenna: Is this antenna mandatory? How ...
1
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1answer
88 views

Tradeoff between embedded chip and external GPS antennas

I'm currently redesigning a board that implements GPS positioning. Until now I've been using a Fastrax IT520 module, which is very nice but has been discontinued. This forces me to rethink my board ...
4
votes
3answers
528 views

DIY NFC boosting antenna for a mobile device

I am very new to this. I'm a dentist trying to improve client flow in a busy office. I would like to develop a cheap proof of concept for an NFC enabled client tracking system using a hacked mobile ...
3
votes
4answers
657 views

Trying to reverse engineer a simple circuit

My only experience with electronics is a bit of playing around with an Arduino starter's kit, but nevertheless I decided to buy a cheap little remote control car and figure out how it works and see if ...
2
votes
3answers
303 views

PCB design consideration for a SMA antenna

I am designing a PCB with the transceiver SX1231 (868MHz) with a SMA connector for the antenna. I don't know much about antennas. I would like to know if there is some parameters I need to be careful ...
3
votes
2answers
484 views

433MHz RF transmission only working when holding usb cable in the air

I'm really puzzled about this. I have a simple transmission between two ATTiny85's going on with a 433MHz receiver and transmitter. The transmitter is in the basement so the signal is rather weak but ...
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3answers
98 views

Altium clear region

I have a four layer board: Signal, GND (internal power plane), VCC (internal ground plane), signal. My design includes a chip antenna that requires a completely cleared region at the edge of the PCB. ...