Home |
Search |
Today's Posts |
|
#1
![]() |
|||
|
|||
![]()
On 23 Sep, 12:02, "Dave" wrote:
"Jimmie D" wrote in message ... "Walter Maxwell" wrote in message .. . On Sat, 22 Sep 2007 19:19:18 -0700, wrote: On Sep 22, 5:40 pm, art wrote: O.K. I may have muddied things. I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. If it does, I doubt it's enough to measure on the air.. The example I gave as for an instance was a quad versus a 1/2 wave dipole. This is readily seen by any operator empirically. I've never seen it here. For that reason, I hardly use loops. Neither vertically oriented, or horizontal as for NVIS use. I don't see them as worth the extra trouble. Being I tested them on 75m using NVIS paths, a noticable difference in efficiency should have been readily apparent. It wasn't. In fact, I usually has slightly better performance using the dipoles, which I think was due to the bulk of the max current portions of the antenna being higher above ground in general. The loop sagged a bit in areas, and wasn't all that high above ground. The more wire near the ground, the more ground loss in general. Mathematically it is proven that way also even tho both are in accordance to Maxwell's laws. Where is the math? You should find a very slight difference at best.. It's common knowledge that even a short piece of wire 1/10 of a wave long will radiate nearly all the power that is applied to it. You can go lots shorter than that if you want. If even a short piece of wire will radiate nearly all the power applied to it, what is the point on harping about some magical properties of a full wave length of wire? Art, you are starting to bark at the moon I'm afraid... I was going to comment on some of your other posts, but I think I'll spare you the increase in blood pressure. All I can say is that you are starting to wander off in mumbo jumbo land again.. Replacing known science with conjured mumbo jumbo is no way to live. MK Art, it distresses me to read the misleading statements you profess to be true in your posts. There is no difference in the 'efficiencies' between a full-wave and a half-wave dipole. Let's assume the wire size and conductivity of each dipole is such that we can say they both radiate 98 percent of the power delivered to them. Let's also say that the same amount of power is delivered to both dipoles. What now is the difference in the radiation between the two dipoles? The only difference is in the SHAPE of the radiation patterns--the full-wave dipole will have a somewhat narrower lobe in the direction broadside to the dipole than that of the half-wave dipole, therefore deriving slightly more gain IN THAT DIRECTION than that of the half-wave, but with less gain than the half-wave in all other directions. Consequently, the total integrated power in either radiation pattern will be exactly the same!!! If you want to express the mathematics of the conditions I described here according to J.C.Maxwell's equations, you will find that Maxwell's equations fit the conditions EXACTLY. Walt, W2DU If any difference at all exist it is that the full wave antenna would be ever so slightly less efficient due to the ohmic losses of the extra wire. Jimmie don't claim that until you have modeled it in full. it "may" What does "may" infere? Is it it 'may' or 'may not' or 'I am not sure' or 'I don't know'? I am not willing to procede with what you say unless you can be more difinitive. What does a house built on sand do? snip ragards Art KB9MZ....XG |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Forum | |||
Why does my police scanner pick up this FM broadcast station on WFM? It does not pick up any other stations. | Scanner | |||
Aerial | Shortwave | |||
AM aerial problem | Antenna | |||
UK DAB homebrew aerial | Antenna | |||
ext aerial | Shortwave |