How to make a fractal antenna for HDTV / DTV plus more on the cheap
Author: William Ruckman / On: Wednesday 31 December 2008 - 19:26:43
Version 1, Updated 12-31-08.
Here is a link to the part of the Nova episode that inspired this design
(Hunting the hidden dimension):
http://www.pbs.org/wgbh/nova/programs/ht/tm/3514.html?site=34&pl=wmp&rate=hi&ch=3
The first thing I would like to discuss is a little history, theory, and
uses for fractal antennas.
Fractal antennas are a recent discovery. First discovered back in 1988
by Nathan Cohen and later published and patented in 1995. A fractal antenna
has a few unique attributes as seen in this definition from Wikipedia:
"A fractal antenna is an antenna that uses a fractal, self-similar design
to maximize the length, or increase the perimeter (on inside sections
or the outer structure), of material that can receive or transmit electromagnetic
signals within a given total surface area or volume."
What exactly does that mean? Well, you need to know what a fractal is.
Also from Wikipedia:
"A fractal is generally a rough or fragmented geometric shape that can
be split into parts, each of which is (at least approximately) a reduced-size
copy of the whole,a property called self-similarity."
So basically, a fractal is a geometric shape that repeats and appears
over and over no matter how far out or how far in you zoom magnification.
For visual clarification, here is a picture of the patented antenna:
Source: Wikipedia and http://patimg2.uspto.gov/.piw?PageNum=6&docid=US007088965
Patent number: 7088965]
Fractal antennas have been found to be approximately 20% more efficient
than normal antennas. Which could be useful. Especially if you want to
make your own TV antenna to pick up over the air digital or high definition
video, increase your cellular range, wifi range, FM or AM radio reception,
and so on. Most cell phones already have built in fractal antennas. If
you noticed in the past few years that cell phones no longer have antennas
on the outside. That is because they have a internal fractal antenna etched
on a circuit board which allows them to get better reception and pick
up more frequencies such as bluetooth, cellular, and WIFI all from one
antenna at the same time!
Wikipedia info:
"A fractal antenna's response differs markedly from traditional antenna
designs, in that it is capable of operating with good-to-excellent performance
at many different frequencies simultaneously. Normally standard antennas
have to be "cut" for the frequency for which they are to be used—and thus
the standard antennas only work well at that frequency. This makes the
fractal antenna an excellent design for wideband and multiband applications."
The trick is to design your fractal antenna to resonate at what ever center
frequency you wish to receive. Which means it will look different and
be sized different depending on what you want to receive. A little math
can be used to figure this out. (Or a online calculator)
In my example, I am going to make a simple one but you may want to make
a more elaborate one. The more elaborate the better. I will use a spool
of 18 Gauge solid core wire to make a antenna as an example but you could
go as far as to etch your own circuit boards for aesthetic reasons, to
make it smaller, or more elaborate with more resolution and resonance.
I am going to use the example of making a TV antenna for digital or high
definition reception for over the air broadcasts. It is easier to work
with these frequencies and they fall around half a foot to a few feet
in length for half wavelengths of the signal. I am also going to base
it off a common dipole antenna for simplicity and cheapness of parts for
VHF. For UHF you may want to add a director or reflector which will also
make it more direction dependent. VHF is direction dependent as well but
instead of pointing directly at the TV station like UHF you want VHF rabbit
ears (dipole antenna) to be perpendicular to the TV station. But there
is a little more design to that. I want to keep this as simple as possible
as it is already a very complex subject.
To start, you may want to find what frequencies you want to receive or
broadcast.
For TV, here is a link to a frequency chart:
http://www.csgnetwork.com/tvfreqtable.html
This is a great site to help choose a antenna, find channel direction
on a compass, antenna type (directional/omnidirectional), channel numbers
for digital and analog, and so on. Check it out:
http://antennaweb.org or http://tvfool.com/
And to calculate the size of the antenna we will use a online calculator
like this one:
http://www.kwarc.org/ant-calc.html
Here is a good PDF on the design and theory:
http://www.phd.etfbl.net/files/Works_PDF/Poprzen%20Nemanja%20.pdf
How to find the wavelength of a signal:
Wavelength in feet = (coefficient of the speed of light in feet) / (frequency
in hertz)
Coefficient of the speed on light in feet = 983571056.43045
Coefficient of the speed on light in meters = 299792458
Coefficient of the speed on light in inches = 11802852700
EXAMPLE HOW TO START: (VHF/UHF dipole array with reflector which works
well for a wide range of frequencies DB2):
(350Mhz - 8 inch quarter wave - 16 inch half wave - which falls in the
Super Band - between channel 13 and 14 which is a center frequency between
the VHF and UHF band for best resonance)
This can be adjusted to work better in your area as your channel spread
may be lower or higher on the band.
Based on ( http://uhfhdtvantenna.blogspot.com/ and http://budgetiq.wordpress.com/2008/07/29/diy-hd-antenna/
and http://members.shaw.ca/hdtvantenna/ and http://current.org/ptv/ptv0821make.pdf
), only the fractal designs allow it to be more compact and responsive
and we will be using the DB2 model which has high gain and already is
pretty compact and popular for indoor and outdoor installs.
Basic supplies (cost me about $15):
Mounting surface such as the plastic project enclosure (8"x6"x3"). http://www.radioshack.com/product/index.jsp?productId=2062285
6 screws. I used steel self tapping sheet metal screws.
A impedance matching transformer 300 ohm to 75 ohm. http://www.radioshack.com/product/index.jsp?productId=2062049
Some 18 gauge solid hook up wire. http://www.radioshack.com/product/index.jsp?productId=2036274
RG-6 coaxial with terminators (and rubber jacket if mounting outside).
Aluminum if using a reflector. The enclosure above came with one.
A sharpie marker or equivalent preferably with a fine tip.
Two pairs of small needle nose pliers.
A ruler of at least 8 inches.
A protractor to measure angle.
A drill and drill bit that is smaller diameter than your screws.
Small wire cutter.
Screw driver or screw gun.
NOTE: Someone was nice enough to create this paper template and post it
to http://instructables.com in the comment section. If you prefer to use
the paper template I have made it available HERE
HDTV / DTV construction PDF paper template
Step one:
Assemble the enclosure with the reflector under the plastic cover.
Step two:
Drill small tap holes on the opposite side from the reflector in the following
positions and place a conductive screw.
Step three:
Cut four 8" pieces of the solid core wire and strip it bare.
Step four:
Use a marker and mark every 1" on the wire. (This is where we are going
to make the bends)
Step five:
You will repeat this step for each wire. Each bend on the wire will be
60 degrees exactly as we will be making equilateral triangles with this
fractal. I used two pairs of pliers and a protractor. Each bend will be
made at the 1” marks. Make sure you visualize the direction of each bend
first before making it! Use the diagram below to help.
Step six:
Cut 2 more pieces of wire at least 6 inches long and strip them. Bend
these wires around the top and bottom screws going longways and contact
the center screws. So all three are contacted. Use the wire cutter and
trim unneeded wire.
Step seven:
Place and screw down each of your fractals to the corner screws.
Step eight:
Attach the impedance matching transformer across the two center screws
and tighten them down.
COMPLETE!
NOTE: The bottom of the antenna is to the right of this picture where
the transformer sticks out.
You may now test your build!. Hook it up and try it out! It worked great
for me!
As you can see from the pic below, each time you divide each section and
create a new triangle the length of the wire is the same but can fit in
a smaller space by taking up room in another direction.
Note: I am not an expert on the subject and I don't assume to have all
the answers or information 100% correct. So please, if you find any mistakes
feel free to contact me and let me know and I will correct it.
Windows updates not installing?
Author: William Ruckman
/ On: Thursday 11 September 2008 - 13:01:30
I recently had an issue with a new computer where it refused to install
any new updates. Turns out that it was a .dll issue. This was done on a
Windows XP SP3 machine so I am not sure if it will work on Vista. But this
batch file will fix Windows XP update issues in a snap!
@echo off
net stop WuAuServ
del /Q /S %windir%\SoftwareDistribution
regsvr32.exe %windir%\system32\wuweb.dll
regsvr32.exe %windir%\system32\wups2.dll
regsvr32.exe %windir%\system32\wups.dll
regsvr32.exe %windir%\system32\wucltui.dll
regsvr32.exe %windir%\system32\wuaueng1.dll
regsvr32.exe %windir%\system32\wuaueng.dll
regsvr32.exe %windir%\system32\wuapi.dll
net start WuAuServ
Oh, and…YOUR WELCOME!
LAMPP / XAMPP start up script for CentOS / Fedora / Red Hat
Author: William Ruckman / On: Tuesday 22 April 2008 - 14:09:31
Here is a little script that may help you out if you want to start LAMPP
as a service on linux using chkconfig and service commands.
Place the following code in “/etc/init.d/” with the file name “lampp”
and make sure it is executable.
#!/bin/sh
#
# author: william ruckman ruckman.net
#
# chkconfig: 2345 98 83
#
# description: Starts and stops the LAMPP Server
#
# processname: lampp
# Source function library
. /etc/rc.d/init.d/functions
# Source networking configuration.
. /etc/sysconfig/network
# Check that networking is up.
[ $ = “no” ] && exit 0
RETVAL=0
# See how we were called.
case “$1? in
start)
echo -n “Starting lampp service: ”
echo ” ”
cd /opt/lampp/
./lampp start
sleep 1
RETVAL=$?
;;
stop)
echo -n “Stopping lampp service: ”
echo ” ”
cd /opt/lampp/
./lampp stop
sleep 1
RETVAL=$?
;;
restart|reload)
echo -n “Restarting lampp service: ”
echo ” ”
cd /opt/lampp/
./lampp restart
sleep 1
RETVAL=$?
;;
status)
echo -n “Checking lampp service: ”
echo ” ”
cd /opt/lampp/
./lampp status
sleep 1
RETVAL=$?
;;
*)
echo “Usage: lampp ”
echo ” ”
exit 1
esac
exit $RETVAL
Happy coding!
EeePC Xandros Added Repositories
Author:
William Ruckman / On: Friday 17 August 2007 - 20:56:00
Add the following lines to your /etc/apt/sources.list
deb http://xnv4.xandros.com/xs2.0/upkg-srv2 etch main contrib non-free
deb http://dccamirror.xandros.com/dccri/ dccri-3.0 main
deb http://www.geekconnection.org xandros4 main
To protect your default install, you must activate pinning so that your
main distribution packages don’t get overwritten. Which could possibly cause
stability issues.
Add following lines to /etc/apt/preferences (if it does not exist, create
it).
Package: *
Pin: origin update.eeepc.asus.com
Pin-Priority: 950
Package: *
Pin: origin xnv4.xandros.com
Pin-Priority: 900
Package: *
Pin: origin dccamirror.xandros.com
Pin-Priority: 850
Package: *
Pin: origin www.geekconnection.org
Pin-Priority: 800
You can then use apt-get to install additional software.
ADDITIONAL REPOSITORIES:
Video Lan (VLC) testing repository:
deb http://download.videolan.org/pub/videolan/debian/ sid main
Video Lan (VLC) testing source repository (For downloading source):
deb-src http://download.videolan.org/pub/videolan/debian/ sid main
Tor Debian Repository:
deb http://mirror.noreply.org/pub/tor/ sarge main
Tor Debian Repository (For downloading source):
deb-src http://mirror.noreply.org/pub/tor/ sarge main
More Debian Multimedia mirrors can be located here:
http://www.debian-multimedia.org/mirrors.html
Fix slow login on Windows when offsite from domain
Author: William Ruckman
/ On: Wednesday 20 June 2007 - 21:06:00
I recently ran into a interesting issue where a Windows Vista machine would
wait for 2 minutes to login after the password was typed in. But it would
only occur when the laptop was connected to a network with internet access
that was not its normal domain network.
After hooking the laptop to a hub with another PC, i started Wireshark to
log all packets. After sifting through the data I found that it was attempting
to connect to the primary domain controller by domain name, and consecutively
trying to connect to all 5 secondary domain controllers by domain name.
What I found was that the domain names were not pointing to the domain servers
across the internet, which would be dumb, but were trying to resolve the
domain using yahoo name servers which didn’t know the internal sub domains.
It was connecting to Yahoo’s name servers because that is who they have
hosting their external DNS for them. Yahoo’s name servers redirected the
connections to their main website instead because it was a catch-all address.
The problem is in three different places here.
1. Split DNS is being used - They are using a internal DNS server to resolve
their subdomains internally, but these subdomains are not known externally
so when they are remote they do not resolve properly.
2. A catch-all address is being used on yahoo’s name servers - This is causing
any unknown subdomains to be redirected to the main domain name. Which in
this case, is the main website which doesn’t house the domain server.
3. The requests are hitting yahoo’s firewall and it is dropping the packets
instead of sending a ICMP error message - This is causing the TCP connections
to hang for the default amount of time causing windows to wait before logging
in.
This problem is obviously caused by DNS issues. In order to remedy the problem,
I had to fix the broken split DNS issues.
To do this you have two options:
1. Remove the wildcard from DNS.
2. Redirect the problem subdomains to 127.0.0.1
Removing the wildcard from DNS is the preferred solution. This will cause
the DNS server to report “no such name” which will terminate the connection
before it is established.
If you cannot remove the wildcard from DNS then you will want to manually
make DNS records that point to 127.0.0.1
Such as:
* subdomain1.example.com > 127.0.0.1
* subdomain2.example.com > 127.0.0.1
This will cause the connection to redirect to your localhost when offsite
using global DNS. Your localhost will then report that connection unusable
which will terminate the connection right away.
The boot up times decreased by 75%!
From 2 minutes to 30 seconds. That is an improvement! The lesson here is
to make sure your DNS is correct.
Although, it would be nice if Microsoft would release a patch that would
do this in the background after it loads your desktop instead of waiting
for the connections to terminate!
I would also like to thank the genius who set up the DNS incorrectly and
created all this wonderful work for me. Much appreciated!
Ruckman.net owned and operated by William Ruckman
