You didn't mention the height of your radials... interaction with ground
might affect their resonance.
By the way, the length (and height) of elevated radials will affect the
apparent resonant frequency of the overall antenna. However, the most
important thing you need to keep in mind is that all of the individual
verticals in an array like a 4-square should use equal sets of radials.
They don't have to be any particular length -- if you are going to adjust
the length of the verticals in order to bring the antenna into resonance
then you needn't adjust the radials as well.
246/f or 234/f? If you're going to be that picky, then you should actually
model the radials over ground to assure resonance.
----- Original Message -----
From: "Robert Shohet" <kq2m@earthlink.net>
To: <CQ-Contest@contesting.com>
Sent: Monday, January 28, 2008 5:19 AM
Subject: [CQ-Contest] 4 Square/ Raised Radial Questions
> Hi,
>
> I am in the process of fixing my 80 meter 4-square and
> have some questions regarding raised radials.
>
> 1) Since my 4 square is "cut" for 3.65 and the radials need
> to work on 3.5 as well as 3.8mhz, do I cut the radials
> for 3.5 mhz with the thought that slightly too long (for 3.8 mhz)
> is ok?
>
> 2) What is the correct formula for use with raised radials:
>
> Is it 246/f or 234/f?
>
> 3) The radials are all pvc coated. In theory this adds
> 2-5% length to the radial or lowers the resonant freq.
> by 2-5%. Any actual experience to confirm this?
>
> 4) If I use 3 - 4 radials on each of the four "legs",
> does it matter how I orient the radials? Or, put
> another way, if I am putting up radials for the SW leg,
> do I want to orient the radials only in the S, SW and W
> direction for that leg, or do I want to orient them
> S, N, E and W?
>
> 5) I am using Seven 31 material ferrites at the feedpoint
> of each "leg". The ferrites raise the resonant freq.
> of the 1/4 wavelength coax about 20 khz as measured with
> the MFJ 269. Should I cut for the resonant freq. WITH
> the ferrites already in place, or should I cut and tune
> before I put the ferrites on and then live with the change
> in resonant freq.?
>
> Please let me know your thoughts and experiences on this.
>
> Tnx & 73,
>
> Bob KQ2M
> kq2m@earthlink.net
>
>
>
> _______________________________________________
> CQ-Contest mailing list
> CQ-Contest@contesting.com
> http://lists.contesting.com/mailman/listinfo/cq-contest
>
_______________________________________________
CQ-Contest mailing list
CQ-Contest@contesting.com
http://lists.contesting.com/mailman/listinfo/cq-contest
|