Re: LF: Re: Inv L 'FAN' top wires ?

["Graham" <g8fzk@g8fzk.fsnet.co.uk>]

Thanks  Alan , Rick

 

There is a  slope  down from the  top  of the  Ae  , the  side  view  is  about  right  , I have the  ideas that  with  the  fan, the  signal from the   'back'  may be lower  due to  screening  caused  by the  faraday  cage , wire-ground , it  would  form  , but as that's  directly  to  the  house  , may be  not a  too  bad thing  , . .

 

The  other  option may be to  take the  top  wire  on , from the anchor  point , but that  would be  close to the  house

 

Tnx -G,

 

 

From: Alan Melia

Sent: Tuesday, December 03, 2013 11:22 AM

To: rsgb_lf_group@blacksheep.org

Subject: LF: Re: Inv L 'FAN' top wires ?

Hi Graham, this will increase the aerial capacity by around 100 to 120pF provided the new wires are not over/close to lossy foliage/buildings, as the new wires are only the same length as the current wires you will see little increase in Rrad, BUT you will see a proportional decrease in the loss resistance. So the aerial becomes more efficient......this assumes a flat fan not a sloping one. 

 

There is also mileage to be had by connecting the ends of the fan together!! see the measurements Finbar did on the Spiral top loaded systems we tested. http://g3nyk.ham-radio-op.net/spiraltop.htm

 

Approximately, doubling the antenna capacitance halves the  Rloss which is the component determining the antenna current you can drive and hence the ERP.

 

Alan

G3NYK

----- Original Message -----

From: Graham

To: rsgb_lf_group@blacksheep.org

Sent: Tuesday, December 03, 2013 12:20 AM

Subject: LF: Inv L 'FAN' top wires ?

 

Anyone   tried  this  configuration  ?

 

Changing  single   40 ft  top   wire  on inv-L    to  a   FAN

shape  x3 40 Ft  , spaced  about  10 ft  at  far  end   

 

TNx -G,