Antenna dipole

Thread Starter

AndrieGnd

Joined Jun 25, 2019
52
Hi gentlemen, I've studied the dipole's antenna and still a lil in doubt how it's works functionality , could anyone please explain to me how it works and how E, H electromagnetic is related to the dipole of the antenna? and how can I calculate the electrical field of the dipole of the antenna, the amount of the radiation pattern of the antenna, and how to determine the number of "lobes" of the dipole antenna??

Much appreciated, thanks alot.
 

nsaspook

Joined Aug 27, 2009
6,729
Hi gentlemen, I've studied the dipole's antenna and still a lil in doubt how it's works functionality , could anyone please explain to me how it works and how E, H electromagnetic is related to the dipole of the antenna? and how can I calculate the electrical field of the dipole of the antenna, the amount of the radiation pattern of the antenna, and how to determine the number of "lobes" of the dipole antenna??

Much appreciated, thanks alot.
DO like most of us did, hit the books until it registers in your mind. Without the proper foundation, detailed answers will be meaningless to you.
 

Thread Starter

AndrieGnd

Joined Jun 25, 2019
52
DO like most of us did, hit the books until it registers in your mind. Without the proper foundation, detailed answers will be meaningless to you.
but I really read, why I wouldn't read? it would be nice at all to post here without reading!
you gave me the link to the book, but I didn't understand ...the antenna subject like something hard to understand well.. !
that's why I posted .. otherwise I would post at all (If I understand from the book)

I understand the dipole part, the other aspect of how dipole related to spreading signal from antenna I didn't understand, and how can I calculate the electricity field of the dipole antenna that's entering the antenna?
 

SamR

Joined Mar 19, 2019
1,655
Well there is dipole design which you can get some idea of from manufacturers PDFs and then there is atmospheric propagation which is another whole ball of wax. The big first hurdle is SWR and it's elimination to properly load the dipole. And Baluns and transmission cables and proper grounding. Check the ARRL website, they usually have several antenna books available. Then there's slopers, vees, yagis, etc. etc. etc. I learned long ago the best money spent in Ham Radio is on a proper antenna that actually works.
 

nsaspook

Joined Aug 27, 2009
6,729
We mainly used non-resonate antennas with a matching network for HF communications. A whip with a local auto-match at the base was typical. For the lower HF bands a longer wire-rope fan antenna was used with a auto-match.

 

nsaspook

Joined Aug 27, 2009
6,729
but I really read, why I wouldn't read? it would be nice at all to post here without reading!
you gave me the link to the book, but I didn't understand ...the antenna subject like something hard to understand well.. !
that's why I posted .. otherwise I would post at all (If I understand from the book)

I understand the dipole part, the other aspect of how dipole related to spreading signal from antenna I didn't understand, and how can I calculate the electricity field of the dipole antenna that's entering the antenna?
It's really on you. If you find the subject hard to understand that usually means you don't have the necessary basic theory yet to build on. Being able to calculate the electricity field is important but it won't give you the ability to understand the physics of what's happening. The more you know about the basic foundations the easier it becomes to integrate new information.

An example would be basic special relativity. This allows you to understand classical electrodynamics as a consequence of length contraction and the cosmic speed lime. This in effect means the magnetic field is not independent of the electric field. It shows (spacetime geometry provides context) that there is only one electromagnetic field that can be express from the full range from magnetic to electric depending on the frame of the observer.

http://physics.weber.edu/schroeder/mrr/MRRtalk.html

 
Last edited:

SamR

Joined Mar 19, 2019
1,655
I used to work the world on an old Heath HW-101 tube rig. 100W from a pair of 6146W tubes into an inverted Vee 80/40/20M antenna with bandpass filters and an old Cushman 3 element CB beam antenna I retuned for 10M. Borrowed some tree trimmer gafs and topped out a pine tree next to the house to mount the beam and rotor on at my old house. Worked AUS from SE GA on 10M CW and for him it was a phone band. Dang near the opposite side of the world from where I was. I built a huge 2KW LC antenna tuner but never really needed it as my antennas had almost nil SWR. Supposedly that thing could tune an aluminum folding lawn chair to any band. Currently off the air due to hurricane Michael taking out my antennas. I did get an old electrical contractor company I used to use at work to put the all band off center fed dipole and 10M vertical back up and he did it gratis, but SWR out the window and more than my Icom digital rigs autotuner can correct so still needs work and I can't climb to do it anymore even using a bucket truck. Tried to get some of the local hams to help but they weren't interested. Ah well... one of these days...
 

nsaspook

Joined Aug 27, 2009
6,729
I used to work the world on an old Heath HW-101 tube rig. 100W from a pair of 6146W tubes into an inverted Vee 80/40/20M antenna with bandpass filters and an old Cushman 3 element CB beam antenna I retuned for 10M. Borrowed some tree trimmer gafs and topped out a pine tree next to the house to mount the beam and rotor on at my old house. Worked AUS from SE GA on 10M CW and for him it was a phone band. Dang near the opposite side of the world from where I was. I built a huge 2KW LC antenna tuner but never really needed it as my antennas had almost nil SWR. Supposedly that thing could tune an aluminum folding lawn chair to any band. Currently off the air due to hurricane Michael taking out my antennas. I did get an old electrical contractor company I used to use at work to put the all band off center fed dipole and 10M vertical back up and he did it gratis, but SWR out the window and more than my Icom digital rigs autotuner can correct so still needs work and I can't climb to do it anymore even using a bucket truck. Tried to get some of the local hams to help but they weren't interested. Ah well... one of these days...
Part of our 'magic' was getting detailed propagation predictions and ionospheric sounding information so we could formulate a daily frequency plan. With this information we would configure the next set of frequency jumps well in advance of the current HF link going down because of poor propagation. Now sometimes things just fell flat so we lost the skip-wave signals, for this we had a few fallback HF low (~2MHz) or MW frequencies for ground-wave links until RF conditions recovered. When conditions were good, 100W was noise-free across a thousand miles, when conditions were bad, 10,000w and the best antenna got you QRM (we used Z codes, not Q codes).
 

SamR

Joined Mar 19, 2019
1,655
That sounds like that oxymoron Military Intelligence. For me, it was somewhat seat of the pants based on prior experience and some propagation forecasting monthly in QST. Now with the net, there is not only Propagation data and forecasts, but actual real-time worldwide data and analysis across the entire RF spectrum. 40 and 80M were wide open in the winter and unusable due to atmospheric static discharge IE. lightning in the summer (and my neighbor's lawnmower without a resistor spark plug which I offered to install for him for free). 10 - 20 meter more sun-driven.
 

Thread Starter

AndrieGnd

Joined Jun 25, 2019
52
It's really on you. If you find the subject hard to understand that usually means you don't have the necessary basic theory yet to build on. Being able to calculate the electricity field is important but it won't give you the ability to understand the physics of what's happening. The more you know about the basic foundations the easier it becomes to integrate new information.

An example would be basic special relativity. This allows you to understand classical electrodynamics as a consequence of length contraction and the cosmic speed lime. This in effect means the magnetic field is not independent of the electric field. It shows (spacetime geometry provides context) that there is only one electromagnetic field that can be express from the full range from magnetic to electric depending on the frame of the observer.

http://physics.weber.edu/schroeder/mrr/MRRtalk.html

If I work on specific frequency which there's someone else working on the same are with the same frequency, would it be a disturbance between me and him? is working with specific frequency like I'm owning it and who's sharing with me on the same area and frequency would disturb me(my signal on the frequency)?
 

SamR

Joined Mar 19, 2019
1,655
If you can hear them, they can probably hear you. Then you either move to another unused frequency far enough away to prevent "bleed over" to send CQ or wait for a break in the action and try and contact the sender you heard on the frequency in use. Lot more to it than that but that's the gist of it.
 

SamR

Joined Mar 19, 2019
1,655
No idea, I'm an antenna user not a designer. I have built a few dipoles with and without traps over the years and some longwires and slopers. QST magazine will show off some homebrew antennas such a monster 80M 3 element beams from time to time. Most Hams have limited space for antennas and considering that a full wavelength 40M dipole is ~260' end to end so most antennas are not designed for full wave. A lot of Hams struggle along with a multiband vertical which has not as good propagation as a dipole but is all they have room to erect. I use a 10M vertical, but it is full wavelength with ground radials so it is over 30' high with 4 ground radials extending out about 12' each. It's base is mounted on a 30' mast which also supports the center of an all band off-center fed 6-160M dipole that is 270' long not including the nylon cord used to anchor it's ends. But I live on a 3.5-acre lot. I also use a MFJ device which allows me to switch between antennas and has some LC tuning capability for 1.8 - 54MHz along with some attenuation and gain capability to fine tune and preprocess the input signal and antenna match the output signal.
 
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