LF: Re: antenna calculation..help needed

["PA0WFO" <pa0wfo@chello.nl>]

Hello Dick ,

To match a resistive load of 36 Ohms to 50 Ohms you need a L network consisting of  a coil of 0,4 microH from your TX to the antenna and a capacitor of 195 pF from the 50 Ohms side to ground ( freq, 10,140 Mhz ) as calculated with the L matching network calculator ( supplied with the ARRL antennabook ) . I use this calculator quite often with good results . I will send you the program ( Old MS DOS ) in a seperate E-mail .

73, William PA0WFO

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

From: Dick

To: rsgb_lf_group@blacksheep.org

Sent: Wednesday, September 13, 2006 7:06 PM

Subject: LF: antenna calculation..help needed

Hello all,

 

It's off topic, but as I can't find it on the net I'll ask it here.

 

I want to modify an old 27MHz CB antenna to an quarter wave vertical for 30m (10.14MHz)

 

Diameter is tapering from 26 to 15mm.

 

Question: what length should it have? I suppose 0.25 wavelength x 0.96 or so...

 

Sofar not a big problem, but as I will use 36 radials direct on the ground, it's radiation resitance will be

around 36Ohm.

 

To match this to 50Ohm I can use a series capacitor, but what value this should be??

 

Who can tell me?

 

73

 

Dick, pa4vhf