[01:04.900 --> 01:15.180]  Good afternoon. I'm Matthew Shuckman. I'm the founder of WarDrivingWorld.com and I'm
[01:15.180 --> 01:21.880]  here to talk to you about WarDriving hardware and how to build some if you want to WarDrive.
[01:22.180 --> 01:26.740]  Firstly, can I ask a question? How many of you have ever gone WarDriving? Can you raise
[01:26.740 --> 01:35.900]  your hands? Okay, so the rest of you are interested in WarDriving and the ones who have already
[01:35.900 --> 01:50.980]  gone WarDriving want to do some new things, so great. What? Mike? Better? Okay, that's
[01:50.980 --> 02:02.440]  better? Okay, sorry. Yeah, well, I'll be alright. Okay. What is WarDriving? To start off, for
[02:02.440 --> 02:06.900]  those of you who haven't done it, WarDriving is the sport, the name was coined by Peter
[02:06.900 --> 02:14.920]  Shipley, the act of driving around and looking with a laptop computer and locating access
[02:14.920 --> 02:22.080]  points for Wi-Fi networks. You don't necessarily need an antenna, you can use an internal Wi-Fi
[02:22.080 --> 02:29.340]  card on a laptop, but you can only go so far with that. There are a variety of pieces of
[02:29.340 --> 02:35.420]  software that have been shared by their authors or in the public domain, including packages
[02:35.420 --> 02:42.740]  like Morris Miller's NetStumbler, which allow you to record the access points that you find
[02:43.420 --> 02:48.600]  and record some information about them. And there are also packages like Kismet and that
[02:48.600 --> 02:56.860]  variety, which are crap Wi-Fi packets, and then to dissect them a bit and do little bits
[02:56.860 --> 03:13.380]  of surgery on them. First question, is it legal to WarDrive? Okay. Is it legal to WarDrive?
[03:13.820 --> 03:20.800]  It's a good question and it's one that I'm going to be covering more in tomorrow afternoon.
[03:20.800 --> 03:28.500]  There will be a session on the legal and ethical aspects of WarDriving. I'm the chair on that,
[03:29.020 --> 03:36.360]  and Frank Thornton will be there, Robert Hale and RenderMan, and the four of us will be
[03:36.360 --> 03:41.360]  having a panel discussion on some of the current legal issues and some of the ethical issues
[03:41.360 --> 03:50.300]  in terms of WarDriving. So I hope you can join us there. Yes. They've moved the time
[03:50.420 --> 03:54.440]  a few times, but I think it's at 1 p.m. tomorrow. I guess they'll let me know tomorrow. But
[03:55.420 --> 04:01.600]  look forward to seeing you there. Okay. Simply put, the construction of WarDriving tools
[04:02.640 --> 04:08.720]  is legal. And WarDriving is legal as long as you don't try to access a Wi-Fi signal
[04:08.720 --> 04:14.840]  that you don't have permission to access. Simply detecting the signal, so far, all the
[04:14.840 --> 04:20.920]  cases that have come forward have shown that at least accessing the signal is a problem,
[04:20.920 --> 04:27.320]  potentially. But simply detecting the signal is not. The problem comes in when you have
[04:27.460 --> 04:33.300]  a typical case of, let's say at home, I have a link-sys router. I pull the link-sys router
[04:33.300 --> 04:39.420]  out of the box, I configure some security there, and what do I use for an SSID that
[04:39.420 --> 04:47.480]  is the name on the router? Default. Okay? It seems unique. I now have my Windows XP
[04:47.480 --> 04:51.840]  laptop configured that when it sees default, it knows it's my home network and it links
[04:51.840 --> 04:56.580]  to it. While I drive around town, you're going to find a lot of link-sys routers configured
[04:56.580 --> 05:03.580]  with the name of default. And what does Windows do? And when linked up with link-sys, it simply
[05:03.580 --> 05:10.200]  goes and connects to the network, and it thinks it's yours. So, actively you haven't
[05:10.200 --> 05:17.320]  done anything. But the software and the hardware have combined, the software and the firmware
[05:17.320 --> 05:22.460]  have combined basically to allow you to have access to that network. So that's when the
[05:22.460 --> 05:26.820]  question becomes a little tricky. So we'll be discussing that more tomorrow.
[05:34.100 --> 05:40.640]  The original wardrivers were those IT folks who were asked to perform site surveys for
[05:40.640 --> 05:46.960]  the design of Wi-Fi systems. Their purpose was to see where the signal was emanating
[05:46.960 --> 05:53.100]  from, where it was strong, where it was weak, and where it needed to be changed. This is
[05:53.100 --> 05:57.480]  certainly a legal form of wardriving, because they're working with signals that they've
[05:57.480 --> 06:03.560]  been contracted to work with, or they're working with signals in their own company. Yes, there
[06:03.560 --> 06:11.180]  have been a few arrests of people for wardriving. Don't be scared. So far, there have been no
[06:11.180 --> 06:17.040]  cases of anyone arrested for wardriving that wasn't associated with some other nefarious
[06:17.040 --> 06:22.880]  activity. That is, they committed some other crime. Most of us, I think, would agree if
[06:22.880 --> 06:27.800]  you're using... I'll take questions later, thank you. Most of us would agree that if
[06:27.800 --> 06:33.200]  you're dropping in on somebody else's Wi-Fi signal and sending out child pornography as
[06:33.200 --> 06:37.520]  spam, that that's a crime, and that has nothing to do with the fact that they happen to be
[06:37.520 --> 06:43.160]  wardriving while doing it, or going up online on Wi-Fi and stealing people's credit card
[06:43.160 --> 06:47.660]  numbers that are coming across from a retail store. The crime really is not the wardriving,
[06:47.660 --> 06:52.320]  the crime was stealing the credit card numbers. So, so far, there have really been no yet
[06:52.320 --> 07:00.660]  recorded arrests for wardriving. So, to start doing wardriving and performing Wi-Fi site
[07:00.660 --> 07:06.340]  surveys, what do you need? As I said, if you already have a laptop with built-in Wi-Fi,
[07:06.340 --> 07:11.980]  that's all you need. You can drive around with that, and a piece of software like NetStumbler,
[07:11.980 --> 07:17.000]  and you can detect networks. The first time I went wardriving, I lived in South Florida.
[07:17.420 --> 07:25.220]  I drove in a four-mile square, four miles on each side around my house, on major roads.
[07:25.220 --> 07:34.600]  I detected 83 access points. Approximately 15% had some form of protection. All of the
[07:34.600 --> 07:41.040]  others were naked. The SSIDs, that is the name given to the networks that were naked,
[07:41.040 --> 07:47.440]  included a local hospital, two law firms, one of which was named Law Firm, and the other
[07:47.440 --> 07:52.020]  one which was named by the name of the law firm, so certainly they weren't trying to
[07:52.020 --> 08:00.720]  hide, and one bank and one local city agency. Obviously there's a lot of people that are
[08:00.720 --> 08:06.780]  unprotected out there, but enough said about the vulnerability of Wi-Fi. One of the reasons,
[08:06.780 --> 08:11.320]  in a sense, that we all appreciate wardriving is that we are trying to improve the security
[08:11.320 --> 08:17.720]  that exists within Wi-Fi. But again, I don't like to place the blame on the consumers who
[08:17.720 --> 08:22.580]  purchase the equipment which accesses it, or the consumers who have the equipment in
[08:22.580 --> 08:27.440]  their offices. I think that something is up to the, responsibility should be in part with
[08:27.440 --> 08:31.260]  those who design the operating systems and those who design the hardware. They want to
[08:31.260 --> 08:36.980]  make it so easy to use, they make the lack of security a default, rather than security
[08:39.320 --> 08:45.020]  a default. There are different cards to use for Wi-Fi for different purposes. Internal
[08:45.020 --> 08:50.520]  Wi-Fi cards. People come up to me, one of the most common emails we get is, I bought
[08:50.680 --> 08:56.380]  a new Dell 8600, it has great internal Wi-Fi, what do I need to hook up your antenna to
[08:56.380 --> 09:02.780]  it? And I say, it's not going to help you at all. These type of laptops, their Wi-Fi
[09:02.780 --> 09:07.080]  is not upgradable unless you want to open up the screen, solder in a connector, that's
[09:07.080 --> 09:10.480]  going to void your warranty, and I don't want to sell the parts for it because I don't want
[09:10.480 --> 09:17.100]  to get involved in the problems. So, I suggest to them, what you need, generally, is an external
[09:17.100 --> 09:23.260]  Wi-Fi card that you plug in, which has an external connector, which allows you to hook
[09:23.260 --> 09:30.640]  up a variety of antennas. They're more power hungry than the internal card, they are going
[09:30.640 --> 09:36.320]  to draw power, but most people's batteries are in pretty good shape these days. Not all
[09:36.320 --> 09:42.060]  Wi-Fi, external Wi-Fi cards, PCMCIA or Cardbus, that have external antenna connectors are
[09:42.060 --> 09:49.680]  created equal. They run the full gamut. But there is no one Wi-Fi card which is the best.
[09:50.060 --> 09:55.700]  Some people prefer, the two chipsets that are most commonly used are the ones based
[09:55.700 --> 10:01.780]  on the Hermes or the Orinoco Classic Gold, and the other one is the ones based on the
[10:01.780 --> 10:08.740]  Prism chipset. Again, they are both different cards. The Orinoco Gold Classic was manufactured
[10:08.740 --> 10:15.080]  by Orinoco. It was related to when it was part of Lucent. And when it was made, it was
[10:15.080 --> 10:20.540]  not only manufactured for Lucent as an Orinoco card, it was manufactured under private label
[10:20.540 --> 10:31.420]  for Anterasys, 2Wire, Deltru Mobile, Compaq, Toshiba. At one point, just about every Wi-Fi
[10:31.420 --> 10:40.340]  card you picked up was really an Orinoco. And it was a very nice design. Proxim bought
[10:40.340 --> 10:47.540]  the hardware licenses from Orinoco, and a company called Ageri bought the software licenses.
[10:47.620 --> 10:52.320]  So when you use a Gold Classic card these days, most of the time you are ending up putting
[10:52.480 --> 10:57.340]  a card in, if it is a new one, it is manufactured by Proxim, and the software still comes from
[10:57.340 --> 11:03.100]  Ageri. So people often ask me, when they get a card, here is a real Orinoco. Is there any
[11:03.100 --> 11:08.100]  difference between this and the Compaq? There are about 2 bytes of difference. But on a
[11:08.100 --> 11:14.420]  performance basis, there is no difference. And they will both run the same drivers.
[11:14.420 --> 11:22.900]  The Proxim 2 based cards come in a variety of packages. Many Linux users prefer it. In
[11:22.900 --> 11:28.080]  particular, there is a Cisco version, which is a 100 mW card. The Orinoco cards are only
[11:28.080 --> 11:35.120]  running at about 35 mW. There is also an SMC version, which is at 200 mW, and I think they
[11:35.120 --> 11:39.840]  have now come out with a 300 mW version. So if you want power, the Proxim is a good card
[11:39.840 --> 11:44.640]  to go to. But if you try pumping out 200 mW on a continuous basis, you will certainly
[11:44.640 --> 11:53.590]  drain your batteries quite quickly. One of the important issues when working with a card,
[11:53.590 --> 11:59.890]  and you want to do serious war driving, and serious war driving would involve accepting
[11:59.890 --> 12:07.330]  some packets and examining their contents. This is what we would call promiscuous mode.
[12:08.070 --> 12:16.830]  Promiscuous mode is not as naughty as it sounds. It relates to networking, where you have a
[12:16.830 --> 12:22.690]  Wi-Fi card, which is able to recognize and accept all the network traffic which comes
[12:22.690 --> 12:30.450]  along, passively. So it's basically somewhat stealthy, and it's just sitting there and
[12:30.450 --> 12:36.890]  listening. And generally you not only need a promiscuous mode card that will do it, you
[12:36.890 --> 12:43.050]  also need a driver that will allow you to do it. I put it this way, if you want to listen
[12:43.050 --> 12:48.530]  to the music of Wi-Fi, and you want to look at the notes that are being played, you need
[12:48.530 --> 12:57.310]  to become promiscuous. One of the important factors in terms of choosing a card is receive
[12:57.310 --> 13:05.370]  sensitivity. Receive sensitivity indicates how faint an RF signal is that can be successfully
[13:05.370 --> 13:12.250]  be received by your card. The lower power level that a card can receive, the better
[13:12.250 --> 13:19.090]  the receive sensitivity. In Wi-Fi equipment, receive sensitivity is generally stated as
[13:19.210 --> 13:26.330]  a function of network speed. It will generally tell you at what speed your sensitivity is.
[13:27.350 --> 13:33.290]  For any given receiver, the higher the data rate, the less sensitive will be the receiver,
[13:33.290 --> 13:38.070]  because the more power that is required to support that higher data rate. So people often
[13:38.070 --> 13:43.270]  ask me, I'm at a distance, it's dropping down to two megabits. Yes, that's what's going
[13:43.270 --> 13:47.470]  to happen. That's why you put an antenna in, to increase the amount of signal that you're
[13:47.470 --> 13:50.610]  getting, even though you're not increasing the amount of receive sensitivity, so then
[13:50.610 --> 14:02.340]  you can boost up your speed again. I'm not going to do too much math here, just briefly.
[14:02.380 --> 14:07.940]  Receive sensitivity is frequently a confusing issue for people. That is because it's expressed
[14:07.940 --> 14:13.340]  in decibels. It's not generally a unit that most of you are familiar with if you're not
[14:13.900 --> 14:20.860]  working in RF or you're not working in acoustics. A decibel is a ratio expressed on a logarithmic
[14:20.860 --> 14:28.840]  exponential scale. So a 10 to 1 ratio is 10 dB, a 2 to 1 ratio is 3, and a 1 to 1 ratio
[14:28.840 --> 14:36.220]  is 0 dB. While ratios of less than 1 to 1 are expressed as negative numbers, for example
[14:36.360 --> 14:44.220]  a 1 to 2 ratio equals minus 3 dB. Receive sensitivity, when you look at a card and the
[14:44.220 --> 14:49.840]  specifications, is expressed using a version of decibel employed in measurements of radio
[14:49.840 --> 14:59.460]  power, the dBm scale. 0 dBm equals 1 milliwatt. That's what I have on the scale. A power of
[14:59.460 --> 15:09.300]  100 milliwatts equals 20 dBm. And 1000 milliwatts equals 30 dBm. Power levels below 1 milliwatt
[15:09.300 --> 15:13.520]  are expressed as a negative number. That's just what happens when you're looking at something
[15:13.520 --> 15:19.320]  logarithmically. But when you need to compare the receive sensitivity, for example, 0.01
[15:19.320 --> 15:26.120]  milliwatts would be minus 20 dBm. And so when taking a look at it, what you really have
[15:26.120 --> 15:33.760]  to look at is the absolute value. What I mean by that is a signal of minus 98 dBm.
[15:34.900 --> 15:40.260]  Sensitivity is much better than sensitivity at minus 95 dBm.
[15:44.300 --> 15:53.820]  Let's take a look at antennas for a moment. The simplest antenna, and what I'm going to
[15:53.820 --> 16:00.980]  tell you, if any of you came to the booth in the vendor area this week, everybody wants
[16:00.980 --> 16:07.600]  the biggest antenna. It's an American tradition. Bigger is always better. In war driving, bigger
[16:07.600 --> 16:15.920]  is not always better. And many of you I encourage to buy a lower gain antenna. Why? The radiation
[16:15.920 --> 16:22.340]  pattern of a theoretically perfect omnidirectional antenna is a sphere. That's called an isotropic
[16:22.340 --> 16:30.900]  antenna. However, that only exists in theory. A real antenna cannot have an isotropic, a
[16:30.980 --> 16:37.800]  perfect radiation pattern. The field propagates in a direction perpendicular to the radiating
[16:37.800 --> 16:43.960]  wire. So for a vertical antenna, the field isn't going to propagate up and down as much
[16:43.960 --> 16:50.860]  as it is sideways. That means that a 5 dB antenna is going to go to a certain range,
[16:50.860 --> 16:55.340]  but it will also go up, let's say, to the 15th or the 20th floor if you're in an urban
[16:55.340 --> 17:01.760]  area. If you suddenly go up to a 7 dB or an 8 dB gain antenna, you will get the additional
[17:01.760 --> 17:06.220]  range this way, but you will suddenly maybe not be able to retrieve a signal above the
[17:06.220 --> 17:11.720]  10th floor or the 8th floor. So, that's why if you're in an urban area, bigger is not
[17:11.720 --> 17:21.100]  always better. Directional antennas. The two I'm going to talk about are the Cantena and
[17:21.100 --> 17:33.150]  the Yagi. The antenna we're looking at here on the top is a Yagi. Using a variety of elements
[17:33.150 --> 17:39.950]  that collect, reflect, or radiate the signal, antennas can be constructed so the transmission
[17:39.950 --> 17:47.710]  and reception isn't always equal in all directions. The definition of what a directional antenna
[17:47.710 --> 17:54.110]  is. The first antenna we're going to consider here is the top one. It's called a Yagi-Uda
[17:54.110 --> 18:00.770]  antenna. It's an antenna in which the gain of a single dipole element is enhanced by
[18:00.770 --> 18:10.440]  putting a reflector behind it, a reflector behind it, and then directional elements in
[18:10.440 --> 18:18.520]  front of it, so that you can take a signal and push it forward, have a gain from all
[18:18.520 --> 18:24.420]  the reflected power, and keep it directed on a narrow path. This antenna was invented
[18:24.420 --> 18:31.240]  in 1926 by H. Yagi and S. Uda. Uda's name dropped out along the way, but from what I
[18:31.240 --> 18:36.180]  heard from someone, he's the one who got the original patents. But a Yagi-Uda antenna is
[18:36.300 --> 18:39.780]  a long-time favorite. Any of you who are ham radio enthusiasts, any of you who remember
[18:39.780 --> 18:44.720]  what an old TV antenna looks like? Anybody ever see a TV antenna the days before cable?
[18:44.720 --> 18:50.360]  Right. Those were Yagis, okay? And they were very directional, and that's why you frequently
[18:50.360 --> 18:57.080]  put a rotator on them to rotate it in the direction of the signal. The next antenna
[18:57.080 --> 19:07.420]  we're going to show you is a Cantena. This is the original Heathkit Cantena. This is
[19:07.420 --> 19:11.900]  not an antenna. I only show this to you because some people ask me, how did it get the name
[19:11.900 --> 19:19.460]  Cantena? In the 70s and 80s, this is a product, which is basically a one-gallon paint can
[19:19.460 --> 19:24.700]  that was filled with oil that was used to test radio transmitters. It would dissipate
[19:24.700 --> 19:31.560]  the power up to 1,000 watts. So you put a transmitter on it, and you dissipated the
[19:31.560 --> 19:36.080]  power so that you wouldn't blow out a transmitter if you didn't have an antenna on it. That
[19:36.080 --> 19:45.380]  name came along, and what happened was in about 2001, Andy Clapp presented a novel design
[19:45.380 --> 19:52.420]  for a very simple antenna based on a Pringles can. Many of you have heard of it. The Pringles
[19:52.420 --> 19:58.700]  antenna showed a great potential for a simple, low-cost, less than $10, high-gain directional
[19:58.700 --> 20:03.960]  Wi-Fi antenna. At this point, the other high-gain Wi-Fi antennas that were anywhere near it
[20:03.960 --> 20:09.400]  were several hundred dollars apiece. I don't exactly know who to credit, but along the
[20:09.400 --> 20:16.040]  way, someone simplified the design and came up with what we have for a current tin can
[20:16.040 --> 20:22.500]  waveguide antenna, or cantena. Since it was much easier to build, the cantena became very
[20:22.500 --> 20:33.570]  popular. This is an example of a commercial cantena. Here's what a cantena looks like
[20:33.570 --> 20:39.670]  inside. Essentially, a cantena is constructed out of a can that can range from about 3 to
[20:39.670 --> 20:44.230]  5 inches. You can go lower, you can go higher, but if you want reasonable gain, stay within
[20:44.230 --> 20:50.330]  that range in diameter. The most popular one uses a total can length of approximately 12
[20:50.330 --> 20:59.490]  inches, which on a 3, 3.5 inch cantena results in a gain of about 12 dB, and a beam width
[20:59.490 --> 21:08.000]  of roughly 30 degrees. You can build a cantena yourself, and that's the whole basis for
[21:08.000 --> 21:14.640]  this talk. There are professionally manufactured cantenas, we sell them, there are plenty of
[21:14.640 --> 21:19.320]  them available on eBay and online. But you can very simply build your own cantena, and
[21:19.320 --> 21:24.240]  that's how I started off in this sport, so I want to share that information with you.
[21:24.960 --> 21:30.720]  The tin can waveguide antenna basically acts as a collector, and the closed end on the
[21:30.720 --> 21:38.840]  back here acts as a reflector. What happens is that the 2400 MHz signal that's coming
[21:38.840 --> 21:46.240]  in is reflected off the back, and it intersects with the waveforms that are coming in. As
[21:46.240 --> 21:51.640]  these incoming signals and these reflecting signals meet, there are certain points where
[21:51.640 --> 21:57.780]  there are troughs, and there are certain points where you have a maximum signal. The trick
[21:57.780 --> 22:03.940]  is that if you place the collector at about a 1 quarter wavelength position from the rear
[22:03.940 --> 22:10.220]  of the can, you're on one of the tops. You get the maximum signal collection. At the
[22:10.220 --> 22:15.780]  very closed end of it, you get a zero signal. Anywhere along in the middle, you're going
[22:15.780 --> 22:21.680]  to get a different signal. The optimal position is about 1 quarter wavelength along the way.
[22:24.440 --> 22:29.840]  I'm going to diverge momentarily off the cantenna, because you can't really use a cantenna very
[22:29.840 --> 22:37.360]  well without a pigtail, and I want to explain a little bit about pigtails briefly. Firstly,
[22:37.360 --> 22:44.720]  you don't need a pigtail to use a cantenna. Simply by having a cantenna in proximity to
[22:45.580 --> 22:50.500]  a Wi-Fi card, since it's tuned at the same frequency, there's a certain amount of signal
[22:50.500 --> 22:56.560]  strength that will radiate over, and you will get an increase. But it's minimal, and going
[22:56.560 --> 23:02.100]  through the air, you lose a lot of that signal. So although you don't need a cable to connect
[23:02.100 --> 23:09.160]  the two, I strongly recommend it. What's a pigtail? What's a cable? An extension cable
[23:09.160 --> 23:13.860]  is simply a cable which has two of the same connectors, one at each end. A pigtail is
[23:13.860 --> 23:18.880]  one which has two different connectors. That's the only distinction. The nomenclature isn't
[23:18.880 --> 23:23.920]  that firm, but that's at least how most of us use it. Why are there so many varieties
[23:23.920 --> 23:30.400]  of connectors? We've shown three up here. One, not all connectors are designed to operate
[23:30.400 --> 23:36.280]  efficiently at microwave frequencies. 2.4 gigahertz, which is Wi-Fi, is microwave. It's
[23:36.280 --> 23:40.360]  the same frequency approximately that your microwave oven operates on, except that's
[23:40.360 --> 23:48.860]  running at 4, 5, 800 watts, and we're talking here about milliwatts. One, manufacturers
[23:48.880 --> 23:54.240]  want you to purchase their accessories for their product, so they use a custom connector,
[23:54.240 --> 24:00.400]  and you're forced to use their antennas with their Wi-Fi devices. But it also originated
[24:00.400 --> 24:07.300]  with the FCC. Part 15 of the FCC code says that the frequency we're working in at around
[24:07.300 --> 24:14.480]  2,400 megahertz is in public domain. However, you're limited to an effective radiated power
[24:14.480 --> 24:21.660]  of about 4 watts. The way the FCC managed to limit manufacturers was to say that if
[24:21.660 --> 24:28.080]  you had a D-Link antenna and you had a D-Link router, D-Link had to go and submit approval
[24:28.440 --> 24:39.440]  for the antenna and the router in combination together. And until last year, 2004, the FCC
[24:39.440 --> 24:44.280]  came out with a new ruling which said you could mix and match. Technically, before that
[24:44.280 --> 24:49.760]  summer ruling, if you took an antenna and put it on a Linksys router, you were doing
[24:49.760 --> 24:54.960]  something not permitted by FCC Rule 15, because you might have increased the power above the
[24:54.960 --> 25:03.500]  limit that they wanted to. To comply with the FCC, each manufacturer came up with somewhat
[25:03.500 --> 25:10.140]  of a custom connector and got it approved by the FCC. Some took the popular SMA connector
[25:10.720 --> 25:16.140]  and they reversed the ground and the signal, and you came up with an RP, which is a reverse
[25:16.140 --> 25:23.840]  polarity SMA cable. Others came up with a custom connector called the MC, which is what
[25:23.840 --> 25:29.200]  Orinoco uses. It's somewhat of a fragile connector, but again, we didn't design it. They came
[25:29.200 --> 25:35.480]  up with it, so it was customized for them. Samsung took the SMA connector and reversed
[25:35.480 --> 25:41.920]  the threads on the connector, and you have something called an RT-SMA. So, one thing
[25:41.920 --> 25:45.860]  is, when you get to the point at which you're looking for pigtails, be very careful which
[25:45.860 --> 25:52.180]  pigtail you're looking for. An SMA is not an RP-SMA, it's not an RT-SMA. Look carefully,
[25:52.180 --> 25:56.060]  talk to people you know, go up online, there are some tables for each one of the types
[25:56.060 --> 26:02.360]  of equipment, so that you can find out which type of cable you're going to use. The other
[26:02.360 --> 26:07.720]  important thing to keep in mind with connectors is, people say to me, I'm a CB enthusiast,
[26:07.720 --> 26:14.060]  I have a PL259 connector. It looks about like an N connector. It does. It, however, was
[26:14.060 --> 26:19.840]  never made to operate at microwave frequencies, so you're going to see a lot of loss. Choose
[26:20.200 --> 26:29.640]  a connector, preferably an N, that is efficient at microwave frequencies. Cables. What makes
[26:29.760 --> 26:33.480]  a good cable? People are always calling me up and saying, I want a really, really low
[26:33.480 --> 26:39.040]  loss cable. A really, really low loss cable is about three quarters of an inch in diameter.
[26:39.500 --> 26:47.340]  It takes two people to carry it down the street, okay? But yes, it works. The thicker the central
[26:47.340 --> 26:53.480]  conductor on a coax cable, the stronger the shield, there's almost this direct correlation,
[26:53.480 --> 26:59.420]  the lower the loss of the signal along the cable. However, the thicker the cable, the
[26:59.420 --> 27:06.360]  less flexible. The cables you're generally going to run into are an LMR400, and that's
[27:06.360 --> 27:11.320]  about three quarters of an inch, sometimes almost an inch thick. It's very heavy, it's
[27:11.320 --> 27:17.180]  very bulky, but if I'm running a 50 foot span up to the roof, and I know I'm only going
[27:17.180 --> 27:26.080]  to lose 6cb over 100 feet, here's a piece of LMR400, okay? This is not the type of
[27:26.080 --> 27:35.860]  thing you want to plug into your little laptop, okay? This is what we call equivalent to about
[27:35.860 --> 27:41.580]  an LMR200 cable. It's a lot lighter weight, it's a lot more flexible. If you're going
[27:41.580 --> 27:47.340]  to do a run of 20 feet or less, this is a great cable to use. They call it LMR240, they
[27:47.340 --> 27:56.260]  call it LMR200, they call it low loss 200, it's a great cable to work with. This is an
[27:57.300 --> 28:03.880]  LMR100 cable. Very thin. On the other hand, if I'm trying to connect this into a card
[28:04.560 --> 28:10.600]  that I plugged into my laptop, I certainly couldn't plug in that LMR400 into it. One,
[28:10.600 --> 28:14.520]  there's no place to put the connector. Two, the weight of it would break the connector.
[28:14.920 --> 28:25.580]  So we use pigtails to connect from one size of a connector up to another. Just be careful
[28:25.580 --> 28:29.620]  in a sense, when you're looking for a cable, you have to decide how long it's going to
[28:29.620 --> 28:40.380]  be. Now that you know a little bit about cables, and you know a little bit about connectors,
[28:40.860 --> 28:45.480]  the next step is, you want to build a tin can waveguide antenna. That's what you all
[28:45.480 --> 28:52.520]  came to hear. What are the parts and tools you're going to need? You're going to need
[28:52.640 --> 28:59.040]  a tin can, you're going to need an end connector, you could use another microwave connector,
[28:59.040 --> 29:04.460]  I'm going to use my example using an end connector, the example stays the same. You're going to
[29:04.460 --> 29:08.700]  need a drill or a device to make a hole in the can, you're going to need a short piece
[29:08.700 --> 29:14.020]  of wire, you only need about one and a quarter inches, but I would say start off with about
[29:14.020 --> 29:18.680]  six inches so you can make a few mistakes. You're going to need a soldering iron and
[29:18.680 --> 29:24.720]  solder, a little flux doesn't hurt. My partner here, King Tuna Makes, and he says if you've
[29:24.720 --> 29:30.680]  soldered, put a little flux on it, it's going to make life a lot easier. And most importantly,
[29:31.180 --> 29:39.900]  you're going to need a ruler. Don't do it by line of sight. I'm sorry, by sight. Choosing
[29:40.120 --> 29:53.840]  a can. You can choose many different types of cans. Yes. Um, yes. King Tuna says I build
[29:53.840 --> 30:02.180]  better canned tuna's when I've had a shot of Jack, but we, uh, we've used coffee cans work,
[30:02.180 --> 30:07.720]  um, you can eat beans, baked beans cans work great, particularly anybody, anybody here from
[30:07.720 --> 30:13.460]  England? The baked bean cans are a lot wider there and they're much better for a cantenna.
[30:13.840 --> 30:18.880]  Or you can use or drink scotch at holiday time and it comes in a nice little metal commemorative
[30:18.880 --> 30:25.540]  can, which happens to be almost perfect for a great cantenna. Stoli also provides them.
[30:28.310 --> 30:34.970]  You can download plans for many of the cantennas. We're going to distribute one plan here off of
[30:34.970 --> 30:41.990]  the internet. Some of them will have very exact measurements of how to build it. Relax,
[30:41.990 --> 30:48.750]  you don't have to be that exact. You can be within 10% and still make a good cantenna.
[30:51.410 --> 30:57.950]  There are some dimensions which are important. You start off by having an end connector. This
[30:57.950 --> 31:03.430]  is an end connector. You're going to take this end connector, it has a female end on one end,
[31:03.430 --> 31:08.390]  and it'll have a little stub on the other side. You're going to be soldering a piece of copper
[31:08.390 --> 31:14.870]  wire to that. We have, in my business, we happen to use a little brass tube that we have pre-soldered.
[31:14.870 --> 31:19.270]  You can use a brass tube, you can use copper, you can use a copper piece of wire. They'll all
[31:19.270 --> 31:31.070]  work about the same. You need 1.21 inches for a radiator to be effective. Why? Let's go to the
[31:31.070 --> 31:36.950]  next slide, please. Okay. Now, they've just told me I only have 10 minutes because we started a
[31:36.950 --> 31:43.370]  little late, so I'm going to try to go briefly. The first thing to determine is based on the
[31:43.370 --> 31:49.730]  width of the can, the diameter of the can that you have, will determine what the length is for
[31:49.950 --> 31:56.370]  a wavelength. You need to position the collector one quarter wavelength from the end. That's the
[31:56.370 --> 32:02.370]  optimal point. That is the distance that you have to be careful on. Anywhere a little further,
[32:02.470 --> 32:08.430]  a little less, the antenna will still work, but you'll get lower gain. The other important
[32:08.430 --> 32:15.450]  measurement is what we call L over 4 here, which is the length of the radiator which is going to
[32:15.450 --> 32:23.290]  collect the signal. That should be as close to 1.21 inches as you can. Using a ruler to make
[32:23.290 --> 32:30.370]  an antenna, here's an example of one that my partner King Tuna made. It took him about 15
[32:30.370 --> 32:38.550]  minutes this afternoon. This is made from a 13 inch coffee can, 13 ounce coffee can. It's not
[32:38.550 --> 32:46.190]  the optimal can to do it, but it shows you can do it with any can. At CVS we bought it. You take
[32:46.190 --> 32:51.530]  this can, we've got some plans, you can go up and there's some calculators that we'll give you that
[32:51.530 --> 32:57.030]  are on the internet, which based on the diameter of the can, will tell you the distance out from
[32:57.030 --> 33:04.310]  here that is one quarter wavelength. Cut a hole, in this case we just used a screwdriver and a
[33:04.310 --> 33:11.950]  mallet to cut a hole that's about 5 1⁄8 inches around. You take the radiator that you've
[33:11.950 --> 33:18.930]  constructed, which looks like an end connector, with a 1.21 inch piece of copper wire or brass
[33:18.930 --> 33:25.090]  rod, insert it, screw it down. You don't need for it to be a round connector. If you've got a square
[33:25.090 --> 33:30.390]  connector you can use that, you can screw it in place, you can glue it in place. The other
[33:30.390 --> 33:36.910]  dimensions are not going to be that important. For an optimal cantenna, you want this length to be
[33:36.910 --> 33:43.350]  approximately at least three quarters of a wavelength. For this particular can, which is
[33:43.350 --> 33:50.670]  four inches across, three quarters of a wavelength works out to be 5.15 inches. This happens to be
[33:50.670 --> 33:59.150]  5.25 inches. With a 13 ounce coffee can it just happens to work well. Put it in, screw it down,
[33:59.150 --> 34:03.490]  that's all there is to building a cantenna. Essentially the only part that you're gonna
[34:03.490 --> 34:09.450]  have a problem finding is the end connector. You can get it from radio supply houses, we may even
[34:09.450 --> 34:14.330]  have a few left at our booth, there are plenty of places to buy them on the internet. That,
[34:14.490 --> 34:20.490]  a 1.21 inch radiator, and a good tin can.
[34:22.630 --> 34:35.560]  Take that, this particular one is four inches, 100 millimeters. I could go over the math but
[34:35.560 --> 34:40.200]  basically the distance that you're going to measure from here to there is going to change
[34:40.200 --> 34:49.250]  based on the diameter of the can. If you want, you put a pigtail on,
[34:50.910 --> 34:57.150]  you can then connect it up to your card. A simple cantenna like this, which took about 20 minutes
[34:57.150 --> 35:03.690]  to build, will give you about somewhere between 8 to 10 dB gain. We haven't fully measured this.
[35:03.790 --> 35:08.430]  If you're a lot more careful about the calculations, if you're a lot more careful about the length of
[35:08.430 --> 35:17.710]  the can, you can probably get 12 to 14 dB gain. If we make this shorter, we will get less gain,
[35:17.710 --> 35:23.370]  but then again we'll get a wider signal coming out of it. Some people have made them about four
[35:23.370 --> 35:29.090]  inches or so, and they get about a 50 degree signal breadth. If you make it about 12 inches long,
[35:29.090 --> 35:32.910]  you're going to drop down to about a 25 or a 30 degree signal breadth.
[35:33.170 --> 35:46.050]  We find it very useful to go to Home Depot, pick up a little tripod, threads a 1.25 by 20 inch,
[35:46.050 --> 35:55.770]  1.25 by 20 threaded bolt, put it on there, screw it in, and now you don't have to take your coffee
[35:55.770 --> 36:01.550]  cup and try to measure it to get it off and left to focus it. You can put it on any camera tripod.
[36:02.370 --> 36:08.390]  It's really very simple to build a cantenna. Again, two calculations necessary. The length of
[36:08.390 --> 36:14.230]  this is 1.21, and go and find, either use the plans that we've got for working with a simple
[36:14.230 --> 36:20.190]  coffee can or go on the web. We've got a website where you can go to a calculator and measure this
[36:20.190 --> 36:42.630]  out to this 1.25 wavelength. Any questions? The optimal radiator is a trapezoid, actually a cone,
[36:42.630 --> 36:48.490]  but it's pretty hard to make a cone like that. So by making a rod, we end up trying to get in
[36:48.490 --> 37:02.440]  the middle channel. See me afterwards. What you want is a trapezoid, I think it's six millimeters
[37:02.440 --> 37:13.420]  at the bottom and one millimeter at the top. Again, 1.21 across. That's optimal. Yes? No.
[37:14.480 --> 37:19.880]  We tried it with copper, we tried it with bronze, we even tried it with aluminum. They all work
[37:19.880 --> 37:42.930]  well. We didn't see a significant difference. Yes. Thank you very much.