If this is to be a traditional vertical, it should have a base insulator. If not a slant wire shunt feed is possible. There is no magical number for height. In practice an 80M vertical could be anywh
The unipole must be tapped at some point to get a proper match. You really need to look at the as X and J, not resonance. You can tap for a high impedance and zero reactance on for 50 ohms and reacta
What software are you using? Often modeling software can not handle cages. _______________________________________________ Topband mailing list Topband@contesting.com http://lists.contesting.com/mail
I have EZNEC5 and it delivers large errors with cages. a _______________________________________________ Topband mailing list Topband@contesting.com http://lists.contesting.com/mailman/listinfo/topba
1/4 wave stubs do work. They are frequently used in broadcast work. The problem is with the modeling. You really need a professional (expesnive) program preferrably employing NEC 4. This is one of th
A wide spaced array offers many benefits when possible. In general the is less coupling between the elements results in better less mutual impedance interdependence. When enough space is available a
But that is Apples to Oranges. Three elements will usually yield more gain than two. Typical broadcast arrays use a combination of the two topologies a two row of three in a line with the second row
That would be a function of a number of things unrelated to array topology. It could reflect difference in electrical tower height or how the array is phased. A properly designed vertical array will
This is quite true although some patterns will be closer to theory than others. In a commercial phasor as is used for broadcast there are several elements that must be taken into account. The first i
The best way to handle the problem is to assume the new antenna made an impact on the match. The first step would be to measure the actual resistance and if it is not 50 ohms, reset the tap for 50 oh
Vertical antennas have been shunt fed for over 70 years. There is no magic involved. Very few MW verticals are ever resonant and resonance is irrelevant. The only important thing is to match the TX s
Agreed, my bad semantics. That said I was thinking more of a sloping shunt similar to was was used in broadcast. I don't think many will have a "too tall" problem on 160 M unless some lucky person ha
For most of us a precise model is not possible. EZNEC will give you an approximation. The tower is represented as a cylinder equal to the cross section of the real tower. You could measure the existi
They have stray radiation that the FCC's computer can not model. _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
I think this is all being way over thought. It would be good to go back and study the work of Dr. Brown of RCA in the early 30s. At the time broadcast stations were using various iterations of wire a
Most stations just follow tradition. No station I have built has ever had any radials stolen. They are buried 3 feet down. It takes heavier equipment to do it but it is worth the effort. ____________
Here is a link to that paper. It is easy see what field a radiator of X height will produce with varying number of radials from 2 to 113. From the graphs 15 radials and a 45 deg tower gets reasonably
That makes a lot of sense. The FCC has never allowed any form of parasitic directional array. They want something that has positive control. In the 60s there was no computer modeling so the effect of
The link provided below shows how to calculate EIRP. I think each administration will spell out the requirements of how to legally calculate EIRP. To me it is fairly straight forward. 60M in the US i