CAPACITIVE ANTENNA

FOR 20m

 

After all the impressing results with my Magnetic Loop Antennas I was curious about the results with antennas at the other side of the L/C-Ratio: Capacitive Antennas.

I came across the homepage of Arthur, DL7AHW and after some e-mails forth and back I adopted his formulas.

 

The components from "space" to TRX in my setup are:

  -  Capacitor, aluminium household foil, 440mm high on PVC tube, 53mm diameter x 2m
  -  Inductor coil 15 turns of solid installation wire below capacitor
  -  λ/4 Coax from Coil to RF-Choke, inner conductor connected to coil, sleeve open (!)
  -  RF Choke, 8 turns RG 174 on Amidon FT 114/43 (W1JR-style)
  -  Coax, any length to TRX

 



Cap-Antenna for 20m on my terrace (note power-lines at same level!)

My first contacts with this setup on 20m SSB:

25/05/09, 15.55, OH1TD, Tony, Korpo Is., EU-096, RST 59 out, 54 in,
25/05/09, 19.11, SM6EGJ, Dan, Eggby, RST 59+ out, 57 in


 

Cap-Antenna cut in pieces to fit the suitcase (diagonal 78cm)



Details of coil and connections

 


Cap-Antenna at final place on roof, 12m/ground


 

Additional capacitance for fine tuning

For fine tuning I use pieces of sheet-metal from Coke-(KEO-Beer-!)cans wich fit nicely inside the PVC tube or can be fixed outside. There is no need for a galvanic connection as long as there is an overlap of about 3cm or more.

 

For more details see http://www.qsl.net/hb9mtn/hb9mtn_cap40mant.html

 

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