Topband
[Top] [All Lists]

## Topband: Marconi vs. inverted L

 To: Topband: Marconi vs. inverted L "Craig D. Smith" craig@powersmith.net Tue, 1 Sep 2009 14:10:21 -0600 mailto:topband@contesting.com>
 ```I'm starting to plan for the 160 meter contests. I've used an inverted L in the past with satisfactory results. This is a LOW inverted L, the vertical part being only 43 ft tall. This year I'll be using a Marconi at least some of the time - again with a 43 ft vertical segment and two top wires about 70 ft long each. These two choices are all I can fit on my small lot, hence the sub-optimal dimensions. Both would be fed against a radial field of 32 radials from 30 to 80 ft long (again space constrained). Due to antenna restrictions, I need to take them down during the day and put them up at dusk - actually a fairly fast operation! Have spent a fair amount of time modeling these antennas. As expected, the Marconi shows up as better at low angles - about 3 db better in the direction that is down on the inverted L due to its asymmetry and about equal to the inverted L in the opposite direction. Max radiation angle is 26 degrees for the Marconi vs. 30 degrees for the inverted L. So I will definitely use the Marconi when trying to maximize DX performance. OK, now for the question for you folks. As expected, the Marconi has a vertical null whereas the inverted L has lots of high angle radiation. The two are equal at a vertical angle of 55 degrees, and above that the inverted L is stronger. The Marconi is down about 2 db at 60 degrees, 4 db at 70 degrees and 7 db at 75 degrees. Above 75 degrees, the inverted L is 10 to 15 db better. These numbers are for the direction not favored by the inverted L. My question is: is the better performance of the inverted L above 60 degrees of any practical advantage for working close-in states? Phrasing it another way, what are the optimal take-off angles on 160 for working stations within a radius from 100 to 1000 miles? I'm located in Colorado, if that is any consideration. Thanks and 73 ... Craig AC0DS _______________________________________________ Topband mailing list Topband@contesting.com http://lists.contesting.com/mailman/listinfo/topband ```
 Current Thread Topband: Marconi vs. inverted L, Craig D. Smith <= Re: Topband: Marconi vs. inverted L, DAVID CUTHBERT Re: Topband: Marconi vs. inverted L, Dennis OConnor