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### Optimal frequency for penetrating 1 meter of water using radio waves?

We are attempting to penetrate 1m of water featuring dissolved ions ( assume salinity of sea water) using radio waves. Aside for using wavelengths of very low frequency radio or below, what would be ...
29 views

### Mathematical Modelling of Wireless Power Transfer

I am trying to understand the interaction between a transmitting antenna with a certain transmitting power (denoted PTX in the diagram) and how the radiation pattern of the TX antenna is affected by a ...
39 views

### How to design the range and precision of a radar?

I would like to design the wave characteristics and size of antenna for a radar, but I am quite confused about how to find this information. The radar should have roughly following capabilities: ...
• 161
114 views

### What are the differences between a standing wave ratio meter and a frequency counter?

Im having a hard time understanding what the differences are, I see things on google saying they are both at once and I am really confused.
1 vote
63 views

### Do they sell some sort of non-"consumery" GPS trackers?

I have seen these expensive things that you can put in a moving box while moving, to keep track of your stuff in case the moving people drive away with their truck and steal it. I also see expensive ...
1 vote
68 views

I have a question regarding the demodulation of AM signals in radio systems (like car radio). I know that in order to send the audio signal from the broadcasting station to users we need first to AM ...
1 vote
46 views

### Where do I start with learning how to transfer data via RF

So I literally have no idea where to start but I know what I want to make. The goal is to somehow transmit 25mb/s of data across 15km with high penetration. Acceptable for reaching through trees and ...
1 vote
30 views

### Is there a way to quantify the amount of radiofrequency interference?

Is there a way to quantify the amount of radiofrequency interference? Do any units exist that quantifies how much radiofrequency interference is there?
• 33
53 views

### Why radio communication was limited to military use and did not become popular with general public like cell phones have become today? [closed]

Why did no private company or government try to bring radio communications to general public like we have cell phone today? What were the hurdles and challenges?
• 99
200 views

### Is it possible to build a DIY RLC circuit for a classroom demonstration?

I was describing the mathematics of RLC circuits to my students, and was wondering if it's possible to build an actual RLC circuit with coils of wire and an inductor and a variable capacitor. The ...
• 129
91 views

### In the 1980s, did radio reporters actually carry around a clunky antenna contraption on their backs to communicate with their radio station's HQs?

I've been wondering about this ever since I saw this comedy TV show as a kid called Macken ("The car repair shop" in Swedish). Originally aired 1986 in Sweden, it features absurd situations ...
72 views

### How to connect Arduino to brushless motor through only 1 digital pin

I know how to connect motor to Arduino with 3 wires: 5v, digital pin and ground. As I know only digital wire need to control "speed control" of my motor. So, if my Arduino connected to computer and it ...
1 vote
53 views

### Is it possible for laptop speakers (versus external speakers or headphones) to pick up radio signals?

Heard a strange sound a couple of times last week while web browsing. It sounded very much like I was listening to someone's microphone (e.g. the sound was static-y, it sounded like papers were ...
1 vote
86 views

### How does free space path loss change with receiver's antenna's height

I have a question which seems like an easy one, but I couldn't find anything on Internet to be 100% sure. The free space path loss equation is: FSPL=20\text{log}(d)+20\text{log}(f)+20\text{log}(\...
• 113
1 vote
53 views

### Why is the tv playing if the carrier frequencies in our RF project appear unsupported?

My group made an RCA video/audio to RF modulator for a school project. The video is a NTSC composite video signal. Here is a clip of our tv receiving the output of the project on NTSC channel 2: ...
1 vote
88 views

### Material to absorb very low frequency radio

Is there any material that will absorb very low frequency radio light? I know that stealth aircraft use radar absorbant materials in their design that absorb radio light best at certain frequencies, ...
1 vote
58 views

### Swapping transmitter and receiver locations

Pardon me if this is a silly question, because I don't quite study RF. Let's say I have a set of transmitter (radio + antenna) and a set of receiver (radio + antenna), at location A and B ...
• 111
62 views

### Propagation loss in USRP antenna

Problem I have two USRP antennas close to each other. I know that signal strength on the receiving end has to be at least -80 dBm. Both antennas have 2 dBi of gain. I want to compute what ...
• 121
1 vote
64 views

### Measuring intensity of a radio wave reflected from a metal plate

I am building a Project that can pinpoint location of a pen or any object (something as small as 0.5 mm radius sphere) placed on a flat screen. I am using a ultrasound sensor (initially but i can ...
645 views

### Radio triangulation with Raspberry Pi

Currently, I am thinking that since electromagnetic waves loose energy over distance, you might be able to figure out the relative distance to each of three radio "beacons" and use this information to ...
• 23
390 views

### Ansys multiphysics import deformed mesh to HFSS

I want to run a coupled simulation in Ansys - RF heating and deformation of waveguide. Pictures of project layout and settings are here. I calculated RF fields and surface losses in HFSS; imported ...
• 101
32 views

### Calculating the link budget of antenna and receiver with free space-path-loss formula

I really know that the real calulation of the range of UMTS, GSM or LTE antennas is depending on a lot of issues, reflection, and other stuff which makes it really complex. I need only a rough model ...
1 vote
61 views

### Can a casio fx series do this operation?

"Calculators stackexchange" doesn't exist, so I guessed this would be the right place to ask. Can a calculator solve $-0.2 \cdot e^{-0.06-4.2i}$? Or any $e$ to a complex for that matter. I've been ...
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