I realized the attached Smith chart image did not come through on the reflector so I posted it on the web, here is the chart:
https://www.dropbox.com/s/nwfqr6xhsfdgjjb/Screenshot%202017-03-09%2013.03.33.png?dl=0 73, Matt NQ6N On Thu, Mar 9, 2017 at 12:46 PM, Matt Murphy <[email protected]> wrote: > In preparation for the Stew I'm thinking of setting up a two element > end-fire array aimed at Europe, and possibly another one aimed south. > > I've done some reading about these types of arrays and I think I understand > the approach taken by W8JI in his design of the short verticals he uses, as > well as the design of the YCCC short vertical. > > Just for kicks I decided to model a short vertical that used matching stubs > made with RG-59. > > I'd like to ask for advice on this approach. I would use the array on 160m > only, and the objective is for it to have better RDF than my inverted L, so > even a few dB would be helpful. > > I modeled a 6' vertical element in CocoaNEC and designed a matching network > using SimSmith.I have attached the Smith chart of the matching stubs. > > In my CocoaNEC model, the feed point impedance does not change much if I > increase the length of the element to 30', and the matching network is not > sensitive to changes in the feed point impedance. I wonder if this > matching network might just be equivalent to matching the coax with no > antenna connected (and if so what that means for the antenna's performance) > > Any advice on the antenna, matching network, etc., would be much > appreciated. My next step is to build one and verify that my real world > results for a single element match the model's prediction, and if so, to > subsequently build a second one and connect them with a phasing line to > achieve end-fire directivity over the bottom end of 160m. > > Advice much appreciated. > > 73, Matt NQ6N > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband > _________________ Topband Reflector Archives - http://www.contesting.com/_topband
