freecell said:
Where did I say any differant? EXCUSE ME if I forgot to say MONOPOLE or GROUNDED MARCONI or DIPOLE.
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homebrew antenna question
- Thread starter BIONIC_TEXAN88
- Start date
Where did I say any differant? EXCUSE ME if I forgot to say MONOPOLE or GROUNDED MARCONI or DIPOLE.
freecell said:
Ahh the word "appreciable". That would mean that there is in fact a small differance but not hardley noticeable.So in fact there is a differance albeit a small one just like I said,a SLIGHT differance at the horizon.So where you once said "electromagnetic fields and radiation patterns are the same as for a half-wave dipole. the gain is the same as that for a half-wave dipole." note "the same" and now there is no "appreciable differance".Sure I'm splitting hairs here but I am not the only one here that can do that.
my use of the term appreciable gain amounts to + or - a tenth of a db. one way or the other. easy QRN, we're in agreement.
Sorry, FreeCell. Doc is right;you are wrong.
Although there is not an appreciable difference (Noticeable at the received end) between the two on 11 meters, the difference becomes more apparent in the VHF an UHF ranges. The reason is "ground wave", which diminishes with increased frequency.
The main reason that the ground plane antenna was developed, was as a matching system to bring the higher impedance of the half-wave antenna down to match 50 ohm coax.
Rich
Although there is not an appreciable difference (Noticeable at the received end) between the two on 11 meters, the difference becomes more apparent in the VHF an UHF ranges. The reason is "ground wave", which diminishes with increased frequency.
The main reason that the ground plane antenna was developed, was as a matching system to bring the higher impedance of the half-wave antenna down to match 50 ohm coax.
Rich
Actually,I believe, the groundplane was developed as an alternative to the much longer verticle dipole and was meant to approximate a regular grounded Marconi antenna.Remember that a grounded Marconi antenna is not the same thing exactly as a groundplane antenna. Close in theory but the differance is in the ground return.
"The reason is "ground wave", which diminishes with increased frequency."
how does that make one better than the other if they're both being operated in the vhf/uhf range and ground wave performance is diminished on the basis of the higher operating frequency when they are both subjected to it? ground wave is the reason for what?
"the groundplane was developed as an alternative to the much longer verticle dipole"
yeah, have you ever seen a vertically polarized dipole used in a mobile application?
how does that make one better than the other if they're both being operated in the vhf/uhf range and ground wave performance is diminished on the basis of the higher operating frequency when they are both subjected to it? ground wave is the reason for what?
"the groundplane was developed as an alternative to the much longer verticle dipole"
yeah, have you ever seen a vertically polarized dipole used in a mobile application?
Correct me if I am wrong but was'nt the groundplane developed before mobile radio usage even began?
so how is it that you think that dipole can actually function as a dipole in that mounting location knowing that the radiation field of a dipole is evaluated in both the upper and lower half spaces and that metal objects (like your truck) in the near field are distorting the pattern and creating multiple dipole mirror images as a result of its proximity to the dipole/s, not to mention the fact that it can only produce an omnidirectional pattern in the absence of any surrounding (metal) objects.
...I know it can function as a dipole because it does.
- 'Doc
As for distorting the radiation pattern because of metal around it. So what, the radiation pattern of ~any~ antenna in the same place will be distorted too. 'Mirror images'? Hey, great! Now I've got a multielement, omnidirectional 'beam'.
- 'Doc
As for distorting the radiation pattern because of metal around it. So what, the radiation pattern of ~any~ antenna in the same place will be distorted too. 'Mirror images'? Hey, great! Now I've got a multielement, omnidirectional 'beam'.