Questions tagged [radio]

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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?
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2answers
36 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 ...
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2answers
62 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 ...
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1answer
37 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 ...
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1answer
29 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 ...
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1answer
14 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}(\...
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1answer
40 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: ...
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1answer
59 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, ...
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0answers
39 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 ...
2
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1answer
37 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 ...
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1answer
53 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 ...
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2answers
456 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 ...
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1answer
204 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 ...
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1answer
18 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 ...
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0answers
59 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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0answers
31 views

How do brass models work (radar)?

A common practice in naval research is to construct brass models of ships to study the reflectivity of a vessel. This can (supposedly) be used to understand the way it reacts to radar and the way ...