Hi Guy, in a multiband array using a single boom it's not an easy task to find out where to place planar and different bands elements without affecting negatively the antenna performances on one or m
73 ! Jiri OK1RI Hi Guy, in a multiband array using a single boom it's not an easy task to find out where to place planar and different bands elements without affecting negatively the antenna performa
I sent this earlier but unfortunately only to Pete and not the group. Here it is again. Yes, the linear loading modeling is problematic. However, for this experiment I believe that installing equival
In GENERAL, of course, I have NO argument with your statement of PRINCIPLE, nor have I posted such. But "shadowing" as used by various posters in this thread is an obsolete term that does not intuiti
I have long wondered why the reflector on a yagi is longer than the driven element and why the directors are shorter. Also why do multiple directors increase the gain but multiple reflectors do not?
What makes you think that a 40M SPLIT DIPOLE, Linearly Loaded, will exhibit a resonance on 15M? That may be true for a CONTINUOUS, SELF resonant full size 40M element (that is gamma or T-matched) but
I'm at work, so don't have my diagrams to look at, but I seem to recall that the 40N series DE has an inductor at the center for impedance matching, so it really ISN'T a split dipole. The conundrum y
SNIP it has The simplistic answer is: Reflectors REFLECT (very little signal continues past them to the rear so additional reflectors offer little additional benefit) Directors DIRECT (they focus the
Good point Tom, I purchased EZNEC to see if metal guy cables would effect the radiation pattern for a 3 stack for 20m on a 150 ft. tower. I modeled a single beam then a beam with a boom touching the
This is incorrect when speaking of multi (high density) elements or optimum elements per array wavelength. When you have multiple directors then multiple reflectors DO assist the gain as well as INCR
I don't know about perfect... but I modeled my entire station, including guys insulated from the tower and grounded at their outer ends, and a 2-high stack with the bottom antenna inside the first se
Not going in circles for me. Proof? It's not like this is an unvalidated/unmodeled antenna from a fly-by-night company, though we unfortunately do have some manufacturers of that ilk. For general pur
Mechanical and wind-load considerations aside, is there a significant gain/pattern problem with placing a significantly larger antenna above a smaller one on the same tower? For example, consider a F
On Mon, 29 Jan 2001 09:30:55 -0500 Pete Smith <n4zr@contesting.com> writes: Since the far-field pattern is made up of equal parts of direct ray and ground-reflected ray, it seems to me that it wouldn
That implies ground loss is zero and the near field effect of a large structure near the antenna will have no effect. We can be certain there is some ground loss and that a large antenna mounted nea
The effect of large antenna close to a smaller one is always HUGE. Try to model it and you will see. The effect can be eliminated by changing the sizes of the given antennas, the results are often un
To: <towertalk@contesting.com> No, not ALWAYS. Definitely CAN be huge. In the case of the F12 x40N series of antennas, the linear loading produces an antenna that is not resonant at 15 meters, as op
Hi, I agree. 1. Accuracy of modeling. Even with NEC2 or MININEC you get some results and you get probably lower impedances than the reality but the radiation pattern is probably more-less correct. 2.
The example you quote, C19 and 340N, is probably an exception that proves the rule. In general I agree with W8JI's assessment. These two antennas, though, carry time spent in *developing* an independ
Force 12 C-19XR tribander, with a Force 12 240N 40-meter antenna with 12 feet between them. How do think that would play out. I'm following this with a lot of interest as in the spring I was planning