Topband: question about matching network for short vertical RX antenna

[Matt NQ6N]

I've received word that the Dropbox link was requiring sign-ups to Dropbox,
so I have created a link to the Smith chart using a different image upload
service:

http://imgur.com/a/RmE1Q

73, Matt NQ6N

On Thu, Mar 9, 2017 at 1:04 PM, Matt Murphy <matt at nq6n.com> wrote:

> 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 <matt at nq6n.com> 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
>>
>
>