Topband: beverage lobes

[Larry Molitor]

Tom Rauch <w8ji at contesting.com> wrote:
Since I haven't been in Washington and operated weeks and 
weeks watching antennas, Likewise I have never operated Topband from the eastern seaboard. (But I have several good friends who do) However, when I moved from central AZ to central WA, Topband conditions were so very different that I thought I must have moved into some kind of space/time warp where the basic laws of physics were different!

Besides the issue of dirt, the issue of physical placement on the face of our planet seems to be important. I'm certainly not an expert in these matters but let me throw out a few possibilities.

For one thing, it's farther from me to ALL the population centers with 160 activity by a couple of hops than from the east coast USA. More hops generally means lower arrival angles. (but not always!)  Lower arrival angles would have an impact on the  perceived performance of various RX antennas.

Besides distance, the GCB (great circle bearing) to most 160 activity is through the auroral influence zone for me. W1AW is 80°, through the edge of the aurora.  Many nights, even with a good Beverage on them, I cannot hear W1AW! All of Africa is on the other side of the auroral zone from me! Europe is through the very center of the auroral oval. Does this have any effect on the perceived performance of various RX antennas? If so, how, why? 

How about localized anomalies? N7UA is about 150 miles west of me. N6TR is about 150 miles SW of me. W7LR is about 250 miles east of me. Conditions reported by these stations are almost always significantly different than what I observe. Both openings to various locations and azimuthal arrival angles of received DX stations are different. Usually, but not always. What's this all about? Spotlight effect? Maybe, maybe not. In any case this would surely effect the observed performance of RX antennas.

Regarding the phased systems, based on the limited testing I've done I would expect that a pair of broadside 800 footers would indeed outperform a single 1100 footer. However two local practical considerations far outweigh the theoretical improvement. 

The termination grounds are a real problem for me. Each one requires as much work as stringing out 1100 feet of wire. When it's time to farm, the ground rods have to be pulled up, and it's not always easy to pull them up out of the rock. I frequently need to use the hydraulics on the tractor to get them out. A single 1100 footer has two grounds. A pair of 800 footers has four! Not good!

Single wires can be routed like spokes in a wheel with the feed point grounds close to each other. The feedlines to the switch box are short and can be kept out of harms way. A phased pair needs to be separated by a very large distance requiring the feedlines to be stretched out over a wide area. Between large animals stepping on them, small animals eating them, and farm equipment running over them, it has proven impossible to maintain such a system. I would love to do more work with phased systems but it's just not gonna happen with the conditions I presently have to work under.

BTW, this morning close to my sunrise, I was hearing R1FJT on an EWE pointed to 45°. Go figure......

73, 

Larry - W7IUV
DN07dg - central WA
http://w7iuv.com





 __________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com