[MLB-WIRELESS] Antenna link

[Ratbaggy]

Hi Alan,

I bring the test equipment to most meetings.  If you need to test anything,
just ask and I'll grab the gear from the car.  Having tested quite a few
antennas now, the most successful constructors have used proven designs
constructed to tight tolerances.  A yagi made by Greybeard springs to
mind!!!!!

Another point to remember is that with the indoor measurements we do at the
meetings, we can only measure the antennas ability to absorb energy (Return
Loss or SWR), a good indication that it's working but not the whole story.
The gain and radiation pattern.will still be unknown.

David Nuttall.

----- Original Message ----- 
From: "Alan" <gone_4wding at bigpond.com>
To: "Horace Pinker" <horacepinker at hotmail.com>
Cc: <melbwireless at wireless.org.au>
Sent: Tuesday, May 17, 2005 10:08 PM
Subject: Re: [MLB-WIRELESS] Antenna link


> Horace,
> I tend to agree, I pulled out all of my old electronics books and found
> the formula for calculating the wave lenght. Even using a velocity
> factor of 0.8 which is about the best you could expect from a coat
> hanger I calculated a wave length of exactly 100mm. Using 1/2
> wavelengths the straight sections should be 50mm, or perhaps a bit
> longer if you were using copper wire.
> How often is the anayser at the meetings? any idea who owns it?
>
> Just for interests sake, the formula I used for the wavelength is
>
> Speed of light
> --------------  x 0.8(velocity factor of wire)
> 2.4 Ghz
>
> this works out like
> 300,000,000 metres/second
> ----------------------------- x  0.8    = 0.100 metres
> 2400000000 Cycles/second
>
> My other problem was the connector on the bottom was a PL259 which is
> not exactly rated at 2.4 Ghz. I look in the latest Jaycar catalogue and
> find that they are advertising a ready made 5dB dipole antenna for
> $19.95. Why am I wasting my time!. Mind you they will not be in stock
> until 4th July.
>
> Alan Barrow
>
>
>
> Horace Pinker wrote:
>
> > Hi actually i had very limited success with it, it is good for around
> > the house and it picks up a few things on the roof but nothing over
> > 1Km unless it was amplified to start with(local libraries). So I
> > brought it in to the second last meet and it was put onto the analyser
> > and ..... it bombed out badly, it would seem that it was designed for
> > a totally different frequency or someone didnt do the calcs properly.
> > I have had a look for a formula for calculating the proper lengths
> > and i didnt get too far, as there is a lot of clutter from commercial
> > manufacturers who worked this out and now want to get their dividends
> > to pay up :(
> >
> >> From: Alan <gone_4wding at bigpond.com>
> >> To: Horace Pinker <horacepinker at hotmail.com>
> >> CC: melbwireless at wireless.org.au
> >> Subject: Re: [MLB-WIRELESS] Antenna link
> >> Date: Sat, 14 May 2005 21:58:37 +1000
> >>
> >> Has anyone had any success with this antenna?
> >> I have just made one, well  three actually, the first two wern't
> >> accurate enough so I threw them away.
> >> I have installed it on the roof and I can hardly pick it up from a
> >> room in the house.
> >> The lead I used was the original antenna system of a Belkin card, I
> >> cut the original antenna off and connected it to theis new one.
> >> I made the high gain version with the 4 coils.
> >>
> >>
> >>
> >> Alan
> >>
> >>
> >>
> >>
> >>
> >>
> >> Horace Pinker wrote:
> >>
> >>> Some of you were interested in the antenna i brought to the meeting,
> >>> tho its not new some of you asked for the link, so here it is.
> >>>
> >>> http://www.frars.org.uk/cgi-bin/render.pl?pageid=1071
> >>>
> >>> I have made a template for this antenna and if anyone wants me to
> >>> make them the wire element let me know and i can bring it in for you
> >>> next meeting
> >>> Cheers
> >>>
> >>>
> >>>
> >>> To unsubscribe: send mail to majordomo at wireless.org.au
> >>> with "unsubscribe melbwireless" in the body of the message
> >>>
> >>>
> >>
> >>
> >> To unsubscribe: send mail to majordomo at wireless.org.au
> >> with "unsubscribe melbwireless" in the body of the message
> >>
> >
> >
> >
>
>
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>
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