Voltage the wave form is a sin or a triangle in a dipole antenna

Click For Summary

Discussion Overview

The discussion revolves around the effects of different input voltage waveforms (sine and triangle) on the performance of a dipole antenna, including aspects such as gain, radiation pattern, and output energy. Participants explore the implications of using various waveforms generated by a source, such as a battery or signal generator, in the context of antenna theory and operation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Mica questions the differences in output from a dipole antenna when driven by sine versus triangle waveforms, seeking clarification on how these waveforms affect antenna performance.
  • Some participants express confusion regarding Mica's description of energizing the antenna with a battery, suggesting that the generator is the source of the waveforms.
  • It is noted that an antenna is not an open circuit; it requires an input impedance to radiate power effectively.
  • One participant explains that a square wave contains the fundamental frequency and all odd harmonics, while a triangle wave contains the fundamental and all harmonics, potentially affecting radiation patterns.
  • Another participant mentions that while harmonics may reflect back to the source causing destructive interference, the fundamental frequency will still radiate the same power.
  • Mica expresses a desire for further understanding and asks for book recommendations that provide case studies on antenna operation.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the specifics of Mica's question or the implications of using different waveforms with the dipole antenna. There are multiple competing views on the effects of harmonics and the nature of the input source.

Contextual Notes

There are limitations in the clarity of Mica's initial questions, and some assumptions about the relationship between the input source and the antenna's operation remain unresolved. The discussion includes varying levels of understanding regarding antenna theory and the effects of different waveforms.

Who May Find This Useful

This discussion may be useful for individuals interested in antenna theory, particularly those exploring the effects of different input waveforms on antenna performance and seeking resources for further study.

Mica
Messages
32
Reaction score
0
Hi,

If my input voltage the wave form is a sin or a triangle in a dipole antenna, what is the difference between these two wave forms?

Thanks,

Mica
 
Engineering news on Phys.org
? ? Huh ? ?
 
Averagesupernova said:
? ? Huh ? ?
What is the problem? Is my problem make sense?

Mica
 
Mica, I think there is a language barrier.

Can you explain your problem in a little more detail, please?
 
enigma said:
Mica, I think there is a language barrier.

Can you explain your problem in a little more detail, please?

I have a dipole antenna, my problem is the input source ( ex : a batterie) which energize the antenna, I think. And this input source I can generated a triangle wave form, I'm right? Like a generator which can generated sin, square, triangle wave forms etc. So, my question is if I put one of these kind of wave forms, what is the different on the output of the antenna (gain, radiation pattern, output energie, etc.)? Well, in my understanding I think the wave form of the input source in a sin wave form, I'm right?

Thanks for the response,

Mica
 
Still not following this. You talk about energizing the antenna with a battery. Doesn't make sense. Maybe you are just energizing your sine/triangle generator with battery. I don't know.

Then you are questioning what the gain, radiation and such will be. That I understand.

Then you mention you think the waveform on the input source is a sine wave. Well I imagine it would be whatever you drive the antenna with. Which is your choice.

Now do you see why I said 'huh'? Please elaborate. I think if I understand the question I can help you.
 
O.K. I explain what I understand in antenna. First, an antenna is a open circuit, right? So, to drive an antenna, you need an input source (voltage)which gives the antenna to radiated. Roughly speaking, the whole system is composed a generator and an antenna, right? The output of the generator can be a triangle,square, sin wave form ( like an impluse) ? So, this output is the input to the antenna right? If the output of the generator has a sin, triangle or square wave form then what are the consequences to the antenna? Is this make sense?

Hope this explanation can clarify my problem, thanks again,

Mica
 
An antenna is NOT an open circuit. The job of the antenna is to absorb power from the source and radiate it into space. Think about this: If the antenna is to absorb power it has to have an input impedance. Power cannot be transferred into an open circuit. It can be proven with ohms law.

An antenna will have a fixed impedance at the frequency it is designed for. At other frequencies it will behave differently. At the design frequency the antenna should appear resistive. It is a resonant circuit. As you move in one direction it will appear inductive and the other direction appear capacitive. You will find it may also be resonant at certain harmonics of the design frequency but it may not have the same impedance.

Common impedances for antennas can vary. 50 and 70 ohms is common. 300 ohms has been used. You will notice on some antennas that the feedline would appear to have a direct short placed across the feedline. This is an advantage since it is impossible for a static charge from wind to build up between the conductors of the feedline. However, at the design frequency of the antenna the impedance will NOT be zero.

When harmonics are fed into the antenna the radiation pattern can change as well. You can find books written about this as well as every other thing I have stated here.

Now onto your question about different waveforms going into the antenna.

A square wave contains the fundamental frequency and all of the ODD harmonics out to (theororetically) infinity. So what you would have is an antenna radiating harmonics in different directions. Some more efficiently than others.

A triangle wave contains the fundamental and ALL harmonics out to (theororetically) infinity. So the antenna would behave similarly to the square wave example except that would be radiating even more signals.
 
Mica said:
I have a dipole antenna, my problem is the input source ( ex : a batterie) which energize the antenna, I think. And this input source I can generated a triangle wave form, I'm right? Like a generator which can generated sin, square, triangle wave forms etc. So, my question is if I put one of these kind of wave forms, what is the different on the output of the antenna (gain, radiation pattern, output energie, etc.)? Well, in my understanding I think the wave form of the input source in a sin wave form, I'm right?

Thanks for the response,

Mica

Think about it. A triangle or square wave can be made by adding up sine wave. For square wave, I think, all the odd harmonics and for a triangle wave all the even harmonics.

For the antenna to radiate (output) all the input energy, the wavelength must match the length of the dipole. When you use a triangle input, the harmonics will decrease the output by reflecting back to the source causing deconstructive interference.

Regards

Don
 
  • #10
dlgoff you mention that the harmonics will be reflected back to the source and cause deconstructive interference. This is true but the fundamental will still radiate the same power. I'm not sure if you implied this or not. Some harmonics will radiate better than others.
 
  • #11
Mica - I'm not sure I understand your question. I think what you want to do is to use your triangular, sine, square, wave... to modulate ( frequency, phase, amplitude, modulation) a much higher frequency carrier wave.
 
  • #12
Thanks for all the information. Now, it clarify a little better for me. Thanks for this open forum, it helps me a lot and I can find answer that I don't need to run around and end up with nothing. I need a good book for starter in understanding Antenna. I need a book which has a lot for examples, any suggestions? I have a book in Antenna Theory and Design but this is not I'm looking for. I want is something like case study, from the input to the output of the antenna. Does exist a book like this?

Thanks again the precious information,
Mica
 
  • #13
Research antenna books concerning amateur radio.
 

Similar threads

Off center fed dipole input impedance vs height above ground
  • · Replies 7 ·
Replies
7
Views
4K
Antenna (Dipole) balun - what is it for?
  • · Replies 14 ·
Replies
14
Views
7K
Am vs Fm variable capacitor receiver, what is the difference?
  • · Replies 2 ·
Replies
2
Views
3K
Off-Center Fed Dipole vs Standard Center Fed Dipole
  • · Replies 7 ·
Replies
7
Views
5K
Input Impedance of off center fed dipoles
  • · Replies 49 ·
2
Replies
49
Views
12K
Using an inductor choke as a receiving antenna for LW radio
  • · Replies 14 ·
Replies
14
Views
3K
High-energy LC oscillatory discharge: what kind of switch?
  • · Replies 19 ·
Replies
19
Views
2K
Design help printed (crossed)-dipole
  • · Replies 15 ·
Replies
15
Views
3K
What do electric and magnetic fields look like around a dipole antenna?
  • · Replies 6 ·
Replies
6
Views
5K
Undergrad Plane wave decomposition of the fields of a dipole antenna
  • · Replies 11 ·
Replies
11
Views
2K