[ale] HDTV antenna for urban areas

[George L. Allen]

1) I was watching a NOVA episode online last night about fractals, that mentioned
fractal antennae, (PBS Nova:
http://www.pbs.org/video/video/1050932219/program/979359664).  Basically -
using a fractal design gives you a compact antenna that has decent gain, but
wide bandwith because you have so many different ways to resonate. Have no idea
what it means for gain or impedance as I only heard of them yesterday - but
apparetnly that's how recent smartphones are handling 2.4Ghz Bluetooth/Wifi and
800 to 1900Mhz cellular with one antenna.

2) Regarding using two separate ones - I wonder if you could use both, setup as an
interferometer, with some sortof RLC circuit where you combine them to adjust
phasing - it'd give you SUPER directivity on main lobe if I remember my radio
astronomy right...

On Tue, Jun 02, 2009 at 10:08:26PM -0400, Jim Kinney wrote:
> That looks like a wind loading problem to me :-) !! Air velocity
> parallel to wave vector = new aim point is vertical
> 
> extra points for new materials costing under $30 total!
> 
> time to cook up a yagi in a chunk of sheetmetal ducting.
> 
> I'm still using just a half-wave dipole (tuned for channel 2) cooked
> up from a chunk of 1/2" pvc pipe with a bare 12G copper folded loop
> cable tied and hot glued in place. $2 balun connects to really crappy
> RG58 coax. I could get MUCH better reception if I put it in my attic
> away from the masonry chimney and out from behind a layer of brick
> wall.
> 
> But I'm still waiting for some thing to watch... maybe I'll actually
> catch MI5 this week.
> 
> On Tue, Jun 2, 2009 at 9:48 PM, Daniel Howard<dhhoward at comcast.net> wrote:
> > As a small token of my appreciation to the list, and since some folks
> > have posted recently about setting up off air HDTV reception with the
> > transition date looming, I thought you guys would enjoy some solutions
> > I've run across for dealing with the extensive multipath you get in
> > dense urban areas for HDTV reception.  Enjoy, Daniel
> >
> > 1.  My solution: I have two RadioShack large aperture/gain antennas in
> > my attic, each with a low noise amp at the antenna output, and I have an
> > A/B switch in my TV room such that when I see multipath interfering with
> > reception on one antenna, I switch to the other.  The antennas have to
> > be at least 10 lambda apart however since their gain is so high, and at
> > VHF frequencies for Channel 11 (around 200 MHz), this is about 48 ft.,
> > Using a spectrum analyzer revealed the multipath was spatially
> > decorrelated between the two antennas in my attic even though they were
> > only 40 ft. apart.
> >
> > I had to use this solution because I'm in a valley topographically with
> > buildings and land blocking my direct line of sight to the antenna
> > towers.
> >
> > 2.  If you have line of sight to the towers (use www.antennaweb.org),
> > but have lots of big buildings around you, you just need a really
> > directional antenna, here's what my friend at GaTech used.  Make sure to
> > click page two at the bottom of the web site for the second, more robust
> > and easier to manufacture solution that he came up with, brilliant IMHO.
> >
> > http://www.prism.gatech.edu/~wn17/
> >
> > _______________________________________________
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> >
> 
> 
> 
> -- 
> -- 
> James P. Kinney III
> Actively in pursuit of Life, Liberty and Happiness
> 
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