Build a Dipole Antenna with LED: Charge Imbalance Explained

In summary, this guy builds a dipole antenna with an LED and capacitor in parallel in the center. The LED flickers when close to a transmitting cellphone. Current will also flow in the reverse direction once the reverse breakdown voltage is reached. Usually about 6V. The LED will be destroyed by reverse current if too much current flows.
  • #1
greypilgrim
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Hi.

In this video around 6:45, this guy builds a simple dipole antenna with an LED and capacitor in parallel in the center. The LED flickers when close to a transmitting cellphone.

Since the LED only let's current pass in one direction, shouldn't this quickly lead to a charge imbalance between the parts of the antenna and thus create an opposing field so the LED should stop working after a while?
 
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  • #2
greypilgrim said:
Since the LED only let's current pass in one direction, shouldn't this quickly lead to a charge imbalance between the parts of the antenna and thus create an opposing field so the LED should stop working after a while?
Current will also flow in the reverse direction once the reverse breakdown voltage is reached. Usually about 6V. The LED will be destroyed by reverse current if too much current flows.
 
  • #3
This is not a LED.

upload_2017-3-17_7-5-20.png
 
  • #4
Yes, but he only uses this lamp in the first experiment. In the second part of the video he clearly uses an LED. The label can be seen at 7:08.
 
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  • #5
greypilgrim said:
Yes, but he only uses this lamp in the first experiment. In the second part of the video he clearly uses an LED. The label can be seen at 7:08.

yes agreed
I have issues with that it is supposed to be a capacitor in parallel with the LED, ceramic Capacitors DONT have black band on one end of them
BUT there are plenty of diodes that are blue bodied and have black bands on one end ... a capacitor in there just doesn't make sense

it's a pity that the video isn't in English so that the narration could be understood !

This would be a more logical setup
the LED conducts 1/2 the cycle, the diode conducts the other 1/2 cycle so there is no build-up of charge at one end

and that situation I have often used as a RF detector ... works very well

upload_2017-3-18_11-3-18.png


cheers
Dave
 
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Related to Build a Dipole Antenna with LED: Charge Imbalance Explained

1. What is a dipole antenna and how does it work?

A dipole antenna is a type of radio antenna that consists of two conductive elements, typically metal rods, that are aligned along the same axis. It works by converting electrical energy into electromagnetic radiation, which can then be transmitted or received by the antenna.

2. How do you build a dipole antenna with LED?

To build a dipole antenna with LED, you will need two metal rods, a coaxial cable, a resistor, and an LED. The metal rods should be cut to a length that is half the wavelength of the radio frequency you want to receive. Next, connect one end of the coaxial cable to the two metal rods, and the other end to the resistor and LED. Finally, connect the other end of the LED to a power source, and the antenna is ready to use.

3. What is charge imbalance and how does it affect a dipole antenna with LED?

Charge imbalance refers to the unequal distribution of electrical charge between the two conductive elements of a dipole antenna. This imbalance creates an oscillating current that generates the electromagnetic field necessary for the antenna to function. In a dipole antenna with LED, the charge imbalance causes the LED to light up, providing a visual indication of the antenna's performance.

4. What is the significance of using an LED in a dipole antenna?

The use of an LED in a dipole antenna allows for a visual representation of the antenna's performance. When the antenna is functioning properly, the LED will light up, indicating that the antenna is receiving or transmitting radio waves. This can be helpful in troubleshooting any issues with the antenna.

5. Can a dipole antenna with LED be used for both transmitting and receiving signals?

Yes, a dipole antenna with LED can be used for both transmitting and receiving signals. The antenna functions the same way for both purposes, converting electrical energy into electromagnetic radiation. The LED will light up regardless of whether the antenna is transmitting or receiving signals.

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