Tagged Questions

1
vote
1answer
26 views

Power delay profile and broadband bus

I came across the following solved question, but I have trouble understanding part of the solution. If anyone could shed some light into this I would be really grateful since this problem has been ...
-3
votes
2answers
93 views

Free space model (wireless communications)

The received power at a given distance = 1km is 1nW . Find the received power at a distance of 5km from the same transmitter , using the Free Space Model. Suppose that frequency is 1800Mhz, ...
4
votes
1answer
267 views

Is it possible to have a device with metal case and wireless charging?

Recently I encountered the following idea: that a mobile device manufacturer is not interested in including wireless charging in his devices because that prohibits him from using metal cases in the ...
2
votes
2answers
160 views

Simplest way for remote power control?

I don't know much electronics (I'm a software engineer). I want to build or buy a remote power control, controlling over SMS or IP. I don't care if I need to implement my own API or do my own ...
2
votes
2answers
250 views

Can 5okW be transferred using resonant wireless power transfer?

I don't mind efficiency or loss, but simply can it be transferred? I'm wondering more about the size of the receiver than the transmitter. If the receiver is positioned within the power transfer field ...
2
votes
2answers
719 views

Is there any difference between “induction” and “resonant” wireless energy transfer?

This article compares two systems for wireless energy transfer - one is by WiTricity and another is Bombardier PRIMOVE. I've read their descriptions thoroughly - to me they both look like resonant ...
6
votes
4answers
556 views

How is inductive wireless charging of a moving vehicle on a public road possible in efficient way?

Looks like one of the major problems of wireless energy transfer is efficiency. For example, Magne Charge high power charging system seems to have about 86% efficiency which means that quite a lot of ...
3
votes
1answer
329 views

What's the need for higher frequency in inductive charging systems?

Consider an inductive charging system like Magne Charge - it has a rather huge "coupler" coil off the vehicle and a corresponding slot on the vehicle and the coils in the "coupler" and in the slot are ...
7
votes
1answer
278 views

Why does short distance wireless energy transfer have such low efficiency?

Wikipedia and numerous other sources cite the following statement about Magne Charge high-power inductive charging system: For example, the Magne Charge system employed high-frequency induction to ...
3
votes
2answers
114 views

Making mesh sensor networks energy efficient

SCENARIO: Say you have a mesh network of sensors that measure something like ambient temperature. The nodes are out of range of the base station; however, there happens to be one intermediate node ...
5
votes
2answers
598 views

How do snap-on induction charging systems not interfere with device functioning

There's a variety of snap-on wireless charging solutions on the market. For example, this one includes a charging mat and a plastic case that is put onto iPhone. I suppose the winding is in the ...
3
votes
2answers
324 views

Attaching electronics to a spinning surface without a battery

I am working with a friend to develop a spinning disk with LED lights on it. The issue we are having is wrapping our minds around the idea of electronics on a surface that is spinning. How do we ...
1
vote
1answer
350 views

What's the technical limit to how small RFID-like system antenna can be?

So far I haven't seen a contactless smart card smaller than a standard credit card. My "biometric" travel passport holds a chip powered off the antenna - I lit the plastic holding the chip through ...
5
votes
3answers
3k views

How would an electric company detect wireless theft of electricity?

As legend goes it is maybe possible to steal electricity from power lines in a wireless way (also see this and this related questions). The legend continues that once someone does that he gets caught ...
3
votes
4answers
371 views

Why don't we have wireless charger in every portable device yet?

Today I found Texas Instruments announced a circuit for wireless charging - all the materials emphasis how tiny, lightweight, portable, efficient and otherwise cool it is. While I of course like the ...