Hi Bob,
After 25 years in this game, I would disagree that there's been no change in
antenna design.
Yes, the fundamentals are inalterable. Folk who have tried to claim such are
snake oil salesmen. Maxcom comes to mind.
But computer modelling has drastically changed the way multiple bands on one
boom is accomplished. Look at even the Telrex designs of the 60s: traps to
effect band changing and compromise positioning of elements to give
reasonable gain and F/B on all bands. Yes, some designs such as the A3 and
A4, or TH7DXX, still do, and still work well (why mess with what works?).
Look at something like the C3S, for example, which uses multiple
parasitically excited driven elements with the beam shaped by elements
placed exactly where they need to be. The result is an antenna that at just
two active elements per band, equals or betters larger older designs. And in
lighter designs using less aluminum. It's been noted several times on here
that a two-element optimized monobander outperforms a 3-el compromise
tribander.
Computer modelling has allowed some designers to build space-saver antennas
that give up very little in gain and F/B despite shortened elements. Or
apply loading techniques to create vertical dipoles that outperform
monopoles of similar length. Or create bent-element (Moxon) antennas that
work very nearly as well as full-size straight element antennas.
Something like the Steppir would not be possible without computers.
Computers haven't been the be-all and end-all of antenna design (some folk
were coming out with interesting ideas before NEC-based modellers were even
dreamt of), but they have certainly accelerated the learning curve.
Granted, even with computer modelling, the proof is in the on-air pudding,
but I think folks like N6BV and others would agree that it's a lot easier to
get into the ballpark now.
It's true that with many things governed by laws of physics that
improvements will generally be incremental in nature. But I think it's safe
to say we know a lot more today about antennas, element interaction and
maximizing gain than Drs. Uda or Yagi did in their day.
73, kelly
ve4xt
----- Original Message -----
From: "AD5VJ Bob" <rtnmi@sbcglobal.net>
To: "'Hector Garcia XE2K'" <j_hector_garcia@sbcglobal.net>;
<towertalk@contesting.com>
Sent: Sunday, January 15, 2006 6:03 PM
Subject: Re: [TowerTalk] Building Antennas
> I have printed all of your replies and want to thank you
> all for taking your time to answer my question.
>
> Now I am in the mode of researching all the answers.
> Thanks one and all.
>
> BTW:
> What spurred this desire to do my own was I downloaded an
> old amateur book from 1959 and was reading the antenna
> section.
>
> One thing that hit me between the eyes was that although
> computers and rigs have changed drastically.
>
> Antennas are the same. Interested there have been no
> advances in antennas, oh sure there have been some who
> say theirs is better different, ect. But when you get
> right down to it the "magic" has not changed at all.
>
>
>
> 73 fer nw,
> Bob AD5VJ
>
> 10X# 37210, FP#-1141, SMIRK#-5177
> http://www.n5iet.com/
> Code may be taking a back seat for now,
> but the pioneering spirit that put the code
> there in the first place is out front of it all.
>
>
>
>
> > -----Original Message-----
> > From: towertalk-bounces@contesting.com
> > [mailto:towertalk-bounces@contesting.com] On Behalf Of
> Hector
> > Garcia XE2K
> > Sent: Sunday, January 15, 2006 4:51 PM
> > To: AD5VJ Bob; towertalk@contesting.com
> > Subject: Re: [TowerTalk] Building Antennas
> >
> > Bob:
> >
> > For what Band you want to build the antenna ?
> >
> > several Vendors offer solutions.
> >
> > some very professionals like DXengineering.
> > others more portable and basic (fishing poles hangin
> > wires)
> > MFJ have parts to complete antenna projects.
> > etc etc
> >
> > also your local welding supply can provide material
> right for
> > your need.
> >
> > --- AD5VJ Bob <rtnmi@sbcglobal.net> wrote:
> >
> > > Hi Guys:
> > >
> > > I am embarking on my first antenna project of any
> significance
> > > (something besides wires).
> > >
> > > I am looking at doing a simple direct coaxial fed 2
> ele
> > yagi to start
> > > with to see if I can even make this happen.
> > >
> > > Can someone please tell me who the supplier's) are for
> the proper
> > > weather resistant mechanical parts for these types of
> projects?
> > >
> > > Stainless Steel screws/nuts/washers
> > > Aluminum Plates
> > > Tapered Aluminum Tubing
> > > Anti-Oxidant coating
> > > Sealant Tape for connectors
> > > Stainless Hose Clamps
> > > Stainless U-Bolts
> > > DID I MISS ANYTHING?? :0)
> > >
> > >
> > >
> > > 73 fer nw,
> > > Bob AD5VJ
> > >
> > > 10X# 37210, FP#-1141, SMIRK#-5177
> > > http://www.n5iet.com/
> > > Code may be taking a back seat for now, but the
> pioneering
> > spirit that
> > > put the code there in the first place is out front of
> it all.
> > >
> > >
> > >
> > >
> > > _______________________________________________
> > >
> > >
> > >
> > > _______________________________________________
> > > TowerTalk mailing list
> > > TowerTalk@contesting.com
> > >
> > http://lists.contesting.com/mailman/listinfo/towertalk
> > >
> >
> >
> > Hector Garcia XE2K / XF1K
> > Mexicali B.C DM22
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
>
>
> _______________________________________________
>
>
>
> _______________________________________________
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