WEBVTT 01:04.900 --> 01:07.500 Good afternoon. 01:09.100 --> 01:11.240 I'm Matthew Shuckman. 01:11.240 --> 01:21.880 I'm the founder of WarDrivingWorld.com and I'm here to talk to you about WarDriving hardware and how to build some if you want to WarDrive. 01:22.180 --> 01:23.640 Firstly, can I ask a question? 01:23.640 --> 01:26.480 How many of you have ever gone WarDriving? 01:26.480 --> 01:27.560 Can you raise your hands? 01:29.820 --> 01:39.200 Okay, so the rest of you are interested in WarDriving and the ones who have already gone WarDriving want to do some new things, so great. 01:43.460 --> 01:44.360 What? 01:46.840 --> 01:47.840 Mike? 01:48.280 --> 01:49.320 Better? 01:49.860 --> 01:51.660 Okay, that's better? 01:51.660 --> 01:53.000 Okay, sorry. 01:54.580 --> 01:56.600 Yeah, well, I'll be alright. 01:56.860 --> 01:57.620 Okay. 02:00.040 --> 02:01.520 What is WarDriving? 02:01.520 --> 02:18.000 To start off, for those of you who haven't done it, WarDriving is the sport, the name was coined by Peter Shipley, the act of driving around and looking with a laptop computer and locating access points for Wi-Fi networks. 02:18.000 --> 02:26.680 You don't necessarily need an antenna, you can use an internal Wi-Fi card on a laptop, but you can only go so far with that. 02:27.180 --> 02:45.780 There are a variety of pieces of software that have been shared by their authors or in the public domain, including packages like Morris Miller's NetStumbler, which allow you to record the access points that you find and record some information about them. 02:45.780 --> 02:58.700 And there are also packages like Kismet and that variety, which are crap Wi-Fi packets, and then to dissect them a bit and do little bits of surgery on them. 02:59.940 --> 03:02.800 First question, is it legal to WarDrive? 03:03.600 --> 03:04.600 Okay. 03:08.340 --> 03:13.380 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 --> 03:26.200 There will be a session on the legal and ethical aspects of WarDriving. 03:26.320 --> 03:42.880 I'm the chair on that, and Frank Thornton will be there, Robert Hale and RenderMan, and the four of us will be having a panel discussion on some of the current legal issues and some of the ethical issues in terms of WarDriving. 03:42.880 --> 03:44.760 So I hope you can join us there. 03:47.060 --> 03:48.100 Yes. 03:49.140 --> 03:52.340 They've moved the time a few times, but I think it's at 1 p.m. 03:52.340 --> 03:53.060 tomorrow. 03:53.060 --> 03:54.440 I guess they'll let me know tomorrow. 03:54.440 --> 03:57.100 But look forward to seeing you there. 03:57.460 --> 03:58.020 Okay. 03:58.760 --> 04:03.960 Simply put, the construction of WarDriving tools is legal. 04:04.000 --> 04:11.080 And WarDriving is legal as long as you don't try to access a Wi-Fi signal that you don't have permission to access. 04:11.380 --> 04:21.820 Simply detecting the signal, so far, all the cases that have come forward have shown that at least accessing the signal is a problem, potentially. 04:21.820 --> 04:24.340 But simply detecting the signal is not. 04:24.660 --> 04:31.680 The problem comes in when you have a typical case of, let's say at home, I have a link-sys router. 04:31.720 --> 04:40.780 I pull the link-sys router out of the box, I configure some security there, and what do I use for an SSID that is the name on the router? 04:41.400 --> 04:42.240 Default. 04:43.160 --> 04:43.920 Okay? 04:43.920 --> 04:45.160 It seems unique. 04:45.940 --> 04:52.620 I now have my Windows XP laptop configured that when it sees default, it knows it's my home network and it links to it. 04:52.700 --> 04:58.040 While I drive around town, you're going to find a lot of link-sys routers configured with the name of default. 04:58.540 --> 05:00.160 And what does Windows do? 05:01.120 --> 05:07.640 And when linked up with link-sys, it simply goes and connects to the network, and it thinks it's yours. 05:07.980 --> 05:11.320 So, actively you haven't done anything. 05:12.320 --> 05:21.720 But the software and the hardware have combined, the software and the firmware have combined basically to allow you to have access to that network. 05:21.720 --> 05:24.400 So that's when the question becomes a little tricky. 05:24.520 --> 05:26.820 So we'll be discussing that more tomorrow. 05:34.100 --> 05:44.040 The original wardrivers were those IT folks who were asked to perform site surveys for the design of Wi-Fi systems. 05:44.060 --> 05:52.240 Their purpose was to see where the signal was emanating from, where it was strong, where it was weak, and where it needed to be changed. 05:52.620 --> 06:01.760 This is certainly a legal form of wardriving, because they're working with signals that they've been contracted to work with, or they're working with signals in their own company. 06:02.860 --> 06:06.280 Yes, there have been a few arrests of people for wardriving. 06:07.500 --> 06:09.100 Don't be scared. 06:09.200 --> 06:18.180 So far, there have been no cases of anyone arrested for wardriving that wasn't associated with some other nefarious activity. 06:18.180 --> 06:20.460 That is, they committed some other crime. 06:20.840 --> 06:25.940 Most of us, I think, would agree if you're using... I'll take questions later, thank you. 06:25.940 --> 06:45.740 Most of us would agree that if you're dropping in on somebody else's Wi-Fi signal and sending out child pornography as spam, that that's a crime, and that has nothing to do with the fact that they happen to be wardriving while doing it, or going up online on Wi-Fi and stealing people's credit card numbers that are coming across from a retail store. 06:45.740 --> 06:50.000 The crime really is not the wardriving, the crime was stealing the credit card numbers. 06:50.260 --> 06:54.420 So, so far, there have really been no yet recorded arrests for wardriving. 06:56.240 --> 07:02.320 So, to start doing wardriving and performing Wi-Fi site surveys, what do you need? 07:02.480 --> 07:07.680 As I said, if you already have a laptop with built-in Wi-Fi, that's all you need. 07:07.680 --> 07:13.820 You can drive around with that, and a piece of software like NetStumbler, and you can detect networks. 07:13.920 --> 07:17.000 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 --> 07:29.400 I detected 83 access points. 07:30.580 --> 07:33.940 Approximately 15% had some form of protection. 07:34.180 --> 07:35.820 All of the others were naked. 07:36.340 --> 07:56.980 The SSIDs, that is the name given to the networks that were naked, included a local hospital, two law firms, one of which was named Law Firm, and the other one which was named by the name of the law firm, so certainly they weren't trying to hide, and one bank and one local city agency. 07:58.880 --> 08:05.400 Obviously there's a lot of people that are unprotected out there, but enough said about the vulnerability of Wi-Fi. 08:05.880 --> 08:13.340 One of the reasons, in a sense, that we all appreciate wardriving is that we are trying to improve the security that exists within Wi-Fi. 08:13.960 --> 08:23.660 But again, I don't like to place the blame on the consumers who purchase the equipment which accesses it, or the consumers who have the equipment in their offices. 08:23.820 --> 08:30.860 I think that something is up to the, responsibility should be in part with those who design the operating systems and those who design the hardware. 08:30.860 --> 08:39.800 They want to make it so easy to use, they make the lack of security a default, rather than security a default. 08:39.800 --> 08:44.060 There are different cards to use for Wi-Fi for different purposes. 08:44.560 --> 08:46.220 Internal Wi-Fi cards. 08:46.900 --> 08:56.940 People come up to me, one of the most common emails we get is, I bought a new Dell 8600, it has great internal Wi-Fi, what do I need to hook up your antenna to it? 08:57.420 --> 09:00.900 And I say, it's not going to help you at all. 09:00.940 --> 09:12.180 These type of laptops, their Wi-Fi is not upgradable unless you want to open up the screen, solder in a connector, that's going to void your warranty, and I don't want to sell the parts for it because I don't want to get involved in the problems. 09:12.500 --> 09:25.380 So, I suggest to them, what you need, generally, is an external Wi-Fi card that you plug in, which has an external connector, which allows you to hook up a variety of antennas. 09:26.740 --> 09:34.620 They're more power hungry than the internal card, they are going to draw power, but most people's batteries are in pretty good shape these days. 09:35.400 --> 09:43.340 Not all Wi-Fi, external Wi-Fi cards, PCMCIA or Cardbus, that have external antenna connectors are created equal. 09:43.700 --> 09:45.840 They run the full gamut. 09:45.900 --> 09:49.680 But there is no one Wi-Fi card which is the best. 09:50.060 --> 10:03.260 Some people prefer, the two chipsets that are most commonly used are the ones based on the Hermes or the Orinoco Classic Gold, and the other one is the ones based on the Prism chipset. 10:04.120 --> 10:06.500 Again, they are both different cards. 10:06.500 --> 10:09.780 The Orinoco Gold Classic was manufactured by Orinoco. 10:09.820 --> 10:12.740 It was related to when it was part of Lucent. 10:13.420 --> 10:29.540 And when it was made, it was not only manufactured for Lucent as an Orinoco card, it was manufactured under private label for Anterasys, 2Wire, Deltru Mobile, Compaq, Toshiba. 10:29.540 --> 10:34.640 At one point, just about every Wi-Fi card you picked up was really an Orinoco. 10:35.520 --> 10:37.760 And it was a very nice design. 10:39.240 --> 10:47.540 Proxim bought the hardware licenses from Orinoco, and a company called Ageri bought the software licenses. 10:47.620 --> 10:58.160 So when you use a Gold Classic card these days, most of the time you are ending up putting a card in, if it is a new one, it is manufactured by Proxim, and the software still comes from Ageri. 10:58.160 --> 11:02.440 So people often ask me, when they get a card, here is a real Orinoco. 11:02.440 --> 11:05.100 Is there any difference between this and the Compaq? 11:05.100 --> 11:07.140 There are about 2 bytes of difference. 11:07.280 --> 11:10.000 But on a performance basis, there is no difference. 11:10.000 --> 11:12.160 And they will both run the same drivers. 11:14.020 --> 11:18.640 The Proxim 2 based cards come in a variety of packages. 11:19.140 --> 11:21.520 Many Linux users prefer it. 11:22.380 --> 11:26.680 In particular, there is a Cisco version, which is a 100 mW card. 11:26.940 --> 11:29.980 The Orinoco cards are only running at about 35 mW. 11:30.440 --> 11:37.500 There is also an SMC version, which is at 200 mW, and I think they have now come out with a 300 mW version. 11:37.500 --> 11:40.680 So if you want power, the Proxim is a good card to go to. 11:40.680 --> 11:46.480 But if you try pumping out 200 mW on a continuous basis, you will certainly drain your batteries quite quickly. 11:50.130 --> 12:03.670 One of the important issues when working with a card, and you want to do serious war driving, and serious war driving would involve accepting some packets and examining their contents. 12:03.870 --> 12:07.330 This is what we would call promiscuous mode. 12:08.070 --> 12:11.130 Promiscuous mode is not as naughty as it sounds. 12:11.810 --> 12:25.110 It relates to networking, where you have a Wi -Fi card, which is able to recognize and accept all the network traffic which comes along, passively. 12:26.470 --> 12:31.210 So it's basically somewhat stealthy, and it's just sitting there and listening. 12:32.290 --> 12:39.790 And generally you not only need a promiscuous mode card that will do it, you also need a driver that will allow you to do it. 12:40.810 --> 12:50.350 I put it this way, if you want to listen to the music of Wi-Fi, and you want to look at the notes that are being played, you need to become promiscuous. 12:52.510 --> 12:58.810 One of the important factors in terms of choosing a card is receive sensitivity. 12:59.630 --> 13:07.910 Receive sensitivity indicates how faint an RF signal is that can be successfully be received by your card. 13:07.910 --> 13:14.030 The lower power level that a card can receive, the better the receive sensitivity. 13:14.370 --> 13:21.050 In Wi-Fi equipment, receive sensitivity is generally stated as a function of network speed. 13:21.150 --> 13:26.330 It will generally tell you at what speed your sensitivity is. 13:27.350 --> 13:37.230 For any given receiver, the higher the data rate, the less sensitive will be the receiver, because the more power that is required to support that higher data rate. 13:37.390 --> 13:41.970 So people often ask me, I'm at a distance, it's dropping down to two megabits. 13:42.070 --> 13:43.750 Yes, that's what's going to happen. 13:43.750 --> 13:52.590 That's why you put an antenna in, to increase the amount of signal that you're getting, even though you're not increasing the amount of receive sensitivity, so then you can boost up your speed again. 13:58.260 --> 14:02.340 I'm not going to do too much math here, just briefly. 14:02.380 --> 14:06.220 Receive sensitivity is frequently a confusing issue for people. 14:06.360 --> 14:09.620 That is because it's expressed in decibels. 14:10.000 --> 14:17.220 It's not generally a unit that most of you are familiar with if you're not working in RF or you're not working in acoustics. 14:17.800 --> 14:22.360 A decibel is a ratio expressed on a logarithmic exponential scale. 14:22.680 --> 14:30.120 So a 10 to 1 ratio is 10 dB, a 2 to 1 ratio is 3, and a 1 to 1 ratio is 0 dB. 14:30.920 --> 14:39.800 While ratios of less than 1 to 1 are expressed as negative numbers, for example a 1 to 2 ratio equals minus 3 dB. 14:40.720 --> 14:53.080 Receive sensitivity, when you look at a card and the specifications, is expressed using a version of decibel employed in measurements of radio power, the dBm scale. 14:53.480 --> 14:56.860 0 dBm equals 1 milliwatt. 14:57.100 --> 14:58.900 That's what I have on the scale. 14:58.900 --> 15:02.420 A power of 100 milliwatts equals 20 dBm. 15:02.480 --> 15:06.140 And 1000 milliwatts equals 30 dBm. 15:07.040 --> 15:11.640 Power levels below 1 milliwatt are expressed as a negative number. 15:11.680 --> 15:14.920 That's just what happens when you're looking at something logarithmically. 15:14.920 --> 15:23.020 But when you need to compare the receive sensitivity, for example, 0.01 milliwatts would be minus 20 dBm. 15:23.960 --> 15:29.260 And so when taking a look at it, what you really have to look at is the absolute value. 15:29.260 --> 15:33.760 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 --> 15:46.820 Let's take a look at antennas for a moment. 15:51.260 --> 16:02.300 The simplest antenna, and what I'm going to tell you, if any of you came to the booth in the vendor area this week, everybody wants the biggest antenna. 16:02.300 --> 16:03.660 It's an American tradition. 16:03.660 --> 16:05.460 Bigger is always better. 16:05.720 --> 16:09.640 In war driving, bigger is not always better. 16:09.640 --> 16:13.620 And many of you I encourage to buy a lower gain antenna. 16:13.980 --> 16:15.160 Why? 16:15.160 --> 16:20.600 The radiation pattern of a theoretically perfect omnidirectional antenna is a sphere. 16:20.860 --> 16:23.520 That's called an isotropic antenna. 16:24.400 --> 16:28.040 However, that only exists in theory. 16:28.420 --> 16:32.780 A real antenna cannot have an isotropic, a perfect radiation pattern. 16:32.780 --> 16:38.600 The field propagates in a direction perpendicular to the radiating wire. 16:38.980 --> 16:45.300 So for a vertical antenna, the field isn't going to propagate up and down as much as it is sideways. 16:45.900 --> 16:55.900 That means that a 5 dB antenna is going to go to a certain range, but it will also go up, let's say, to the 15th or the 20th floor if you're in an urban area. 16:56.280 --> 17:08.600 If you suddenly go up to a 7 dB or an 8 dB gain antenna, you will get the additional range this way, but you will suddenly maybe not be able to retrieve a signal above the 10th floor or the 8th floor. 17:08.640 --> 17:12.760 So, that's why if you're in an urban area, bigger is not always better. 17:15.540 --> 17:17.100 Directional antennas. 17:18.060 --> 17:22.300 The two I'm going to talk about are the Cantena and the Yagi. 17:25.890 --> 17:29.830 The antenna we're looking at here on the top is a Yagi. 17:31.470 --> 17:43.850 Using a variety of elements that collect, reflect, or radiate the signal, antennas can be constructed so the transmission and reception isn't always equal in all directions. 17:45.490 --> 17:48.570 The definition of what a directional antenna is. 17:49.370 --> 17:52.830 The first antenna we're going to consider here is the top one. 17:52.830 --> 17:55.190 It's called a Yagi-Uda antenna. 17:55.450 --> 18:03.150 It's an antenna in which the gain of a single dipole element is enhanced by putting a reflector behind it, 18:06.280 --> 18:22.120 a reflector behind it, and then directional elements in front of it, so that you can take a signal and push it forward, have a gain from all the reflected power, and keep it directed on a narrow path. 18:23.080 --> 18:27.020 This antenna was invented in 1926 by H. 18:27.020 --> 18:27.860 Yagi and S. 18:27.860 --> 18:28.520 Uda. 18:28.920 --> 18:33.860 Uda's name dropped out along the way, but from what I heard from someone, he's the one who got the original patents. 18:34.640 --> 18:37.360 But a Yagi-Uda antenna is a long-time favorite. 18:37.360 --> 18:41.940 Any of you who are ham radio enthusiasts, any of you who remember what an old TV antenna looks like? 18:41.940 --> 18:44.720 Anybody ever see a TV antenna the days before cable? 18:44.720 --> 18:45.400 Right. 18:45.660 --> 18:47.840 Those were Yagis, okay? 18:47.880 --> 18:54.060 And they were very directional, and that's why you frequently put a rotator on them to rotate it in the direction of the signal. 18:55.960 --> 19:00.340 The next antenna we're going to show you is a Cantena. 19:03.760 --> 19:06.640 This is the original Heathkit Cantena. 19:06.940 --> 19:08.700 This is not an antenna. 19:09.060 --> 19:12.820 I only show this to you because some people ask me, how did it get the name Cantena? 19:13.860 --> 19:23.760 In the 70s and 80s, this is a product, which is basically a one-gallon paint can that was filled with oil that was used to test radio transmitters. 19:23.760 --> 19:27.280 It would dissipate the power up to 1,000 watts. 19:27.500 --> 19:35.060 So you put a transmitter on it, and you dissipated the power so that you wouldn't blow out a transmitter if you didn't have an antenna on it. 19:35.640 --> 19:50.080 That name came along, and what happened was in about 2001, Andy Clapp presented a novel design for a very simple antenna based on a Pringles can. 19:50.080 --> 19:51.560 Many of you have heard of it. 19:51.800 --> 20:00.320 The Pringles antenna showed a great potential for a simple, low-cost, less than $10, high-gain directional Wi-Fi antenna. 20:00.580 --> 20:06.040 At this point, the other high-gain Wi-Fi antennas that were anywhere near it were several hundred dollars apiece. 20:06.920 --> 20:19.180 I don't exactly know who to credit, but along the way, someone simplified the design and came up with what we have for a current tin can waveguide antenna, or cantena. 20:19.180 --> 20:23.500 Since it was much easier to build, the cantena became very popular. 20:24.220 --> 20:27.020 This is an example of a commercial cantena. 20:31.870 --> 20:34.550 Here's what a cantena looks like inside. 20:34.790 --> 20:40.850 Essentially, a cantena is constructed out of a can that can range from about 3 to 5 inches. 20:41.130 --> 20:46.570 You can go lower, you can go higher, but if you want reasonable gain, stay within that range in diameter. 20:46.670 --> 21:01.210 The most popular one uses a total can length of approximately 12 inches, which on a 3, 3.5 inch cantena results in a gain of about 12 dB, and a beam width of roughly 30 degrees. 21:04.500 --> 21:08.980 You can build a cantena yourself, and that's the whole basis for this talk. 21:09.940 --> 21:16.560 There are professionally manufactured cantenas, we sell them, there are plenty of them available on eBay and online. 21:16.640 --> 21:24.240 But you can very simply build your own cantena, and that's how I started off in this sport, so I want to share that information with you. 21:24.960 --> 21:33.480 The tin can waveguide antenna basically acts as a collector, and the closed end on the back here acts as a reflector. 21:34.820 --> 21:45.840 What happens is that the 2400 MHz signal that's coming in is reflected off the back, and it intersects with the waveforms that are coming in. 21:45.880 --> 21:56.280 As these incoming signals and these reflecting signals meet, there are certain points where there are troughs, and there are certain points where you have a maximum signal. 21:56.760 --> 22:06.760 The trick is that if you place the collector at about a 1 quarter wavelength position from the rear of the can, you're on one of the tops. 22:06.760 --> 22:09.220 You get the maximum signal collection. 22:09.700 --> 22:14.160 At the very closed end of it, you get a zero signal. 22:14.260 --> 22:16.860 Anywhere along in the middle, you're going to get a different signal. 22:16.860 --> 22:21.680 The optimal position is about 1 quarter wavelength along the way. 22:24.440 --> 22:35.020 I'm going to diverge momentarily off the cantenna, because you can't really use a cantenna very well without a pigtail, and I want to explain a little bit about pigtails briefly. 22:36.580 --> 22:40.300 Firstly, you don't need a pigtail to use a cantenna. 22:40.720 --> 22:55.120 Simply by having a cantenna in proximity to a Wi-Fi card, since it's tuned at the same frequency, there's a certain amount of signal strength that will radiate over, and you will get an increase. 22:55.120 --> 22:58.820 But it's minimal, and going through the air, you lose a lot of that signal. 22:58.920 --> 23:04.400 So although you don't need a cable to connect the two, I strongly recommend it. 23:06.000 --> 23:07.060 What's a pigtail? 23:07.060 --> 23:08.080 What's a cable? 23:08.140 --> 23:12.720 An extension cable is simply a cable which has two of the same connectors, one at each end. 23:13.040 --> 23:15.920 A pigtail is one which has two different connectors. 23:16.160 --> 23:17.700 That's the only distinction. 23:17.960 --> 23:21.720 The nomenclature isn't that firm, but that's at least how most of us use it. 23:22.360 --> 23:24.740 Why are there so many varieties of connectors? 23:24.740 --> 23:26.260 We've shown three up here. 23:26.340 --> 23:32.440 One, not all connectors are designed to operate efficiently at microwave frequencies. 23:32.440 --> 23:35.760 2.4 gigahertz, which is Wi-Fi, is microwave. 23:35.920 --> 23:44.800 It's the same frequency approximately that your microwave oven operates on, except that's running at 4, 5, 800 watts, and we're talking here about milliwatts. 23:47.380 --> 23:58.620 One, manufacturers want you to purchase their accessories for their product, so they use a custom connector, and you're forced to use their antennas with their Wi-Fi devices. 23:59.000 --> 24:01.800 But it also originated with the FCC. 24:02.880 --> 24:10.860 Part 15 of the FCC code says that the frequency we're working in at around 2,400 megahertz is in public domain. 24:11.200 --> 24:16.140 However, you're limited to an effective radiated power of about 4 watts. 24:17.160 --> 24:32.260 The way the FCC managed to limit manufacturers was to say that if you had a D-Link antenna and you had a D-Link router, D-Link had to go and submit approval for the antenna and the router in combination together. 24:33.560 --> 24:43.120 And until last year, 2004, the FCC came out with a new ruling which said you could mix and match. 24:43.220 --> 24:56.420 Technically, before that summer ruling, if you took an antenna and put it on a Linksys router, you were doing something not permitted by FCC Rule 15, because you might have increased the power above the limit that they wanted to. 24:59.540 --> 25:06.500 To comply with the FCC, each manufacturer came up with somewhat of a custom connector and got it approved by the FCC. 25:07.260 --> 25:18.100 Some took the popular SMA connector and they reversed the ground and the signal, and you came up with an RP, which is a reverse polarity SMA cable. 25:18.480 --> 25:25.320 Others came up with a custom connector called the MC, which is what Orinoco uses. 25:25.440 --> 25:28.760 It's somewhat of a fragile connector, but again, we didn't design it. 25:28.760 --> 25:31.500 They came up with it, so it was customized for them. 25:32.440 --> 25:39.760 Samsung took the SMA connector and reversed the threads on the connector, and you have something called an RT-SMA. 25:40.440 --> 25:47.300 So, one thing is, when you get to the point at which you're looking for pigtails, be very careful which pigtail you're looking for. 25:47.300 --> 25:50.980 An SMA is not an RP-SMA, it's not an RT-SMA. 25:51.100 --> 26:00.200 Look carefully, talk to people you know, go up online, there are some tables for each one of the types of equipment, so that you can find out which type of cable you're going to use. 26:01.720 --> 26:10.060 The other important thing to keep in mind with connectors is, people say to me, I'm a CB enthusiast, I have a PL259 connector. 26:10.080 --> 26:12.020 It looks about like an N connector. 26:12.020 --> 26:13.040 It does. 26:13.260 --> 26:19.240 It, however, was never made to operate at microwave frequencies, so you're going to see a lot of loss. 26:19.400 --> 26:25.540 Choose a connector, preferably an N, that is efficient at microwave frequencies. 26:27.000 --> 26:27.960 Cables. 26:28.920 --> 26:30.720 What makes a good cable? 26:30.780 --> 26:34.600 People are always calling me up and saying, I want a really, really low loss cable. 26:34.920 --> 26:39.040 A really, really low loss cable is about three quarters of an inch in diameter. 26:39.500 --> 26:42.920 It takes two people to carry it down the street, okay? 26:42.920 --> 26:44.560 But yes, it works. 26:45.520 --> 26:56.740 The thicker the central conductor on a coax cable, the stronger the shield, there's almost this direct correlation, the lower the loss of the signal along the cable. 26:57.140 --> 27:00.620 However, the thicker the cable, the less flexible. 27:00.920 --> 27:09.440 The cables you're generally going to run into are an LMR400, and that's about three quarters of an inch, sometimes almost an inch thick. 27:09.540 --> 27:24.960 It's very heavy, it's very bulky, but if I'm running a 50 foot span up to the roof, and I know I'm only going to lose 6cb over 100 feet, here's a piece of LMR400, okay? 27:25.180 --> 27:30.580 This is not the type of thing you want to plug into your little laptop, okay? 27:32.100 --> 27:37.880 This is what we call equivalent to about an LMR200 cable. 27:37.900 --> 27:40.740 It's a lot lighter weight, it's a lot more flexible. 27:41.100 --> 27:45.380 If you're going to do a run of 20 feet or less, this is a great cable to use. 27:45.660 --> 27:52.280 They call it LMR240, they call it LMR200, they call it low loss 200, it's a great cable to work with. 27:55.060 --> 27:58.620 This is an LMR100 cable. 27:58.800 --> 28:00.100 Very thin. 28:00.120 --> 28:10.300 On the other hand, if I'm trying to connect this into a card that I plugged into my laptop, I certainly couldn't plug in that LMR400 into it. 28:10.300 --> 28:12.140 One, there's no place to put the connector. 28:12.140 --> 28:14.520 Two, the weight of it would break the connector. 28:14.920 --> 28:24.280 So we use pigtails to connect from one size of a connector up to another. 28:24.680 --> 28:30.260 Just be careful in a sense, when you're looking for a cable, you have to decide how long it's going to be. 28:36.140 --> 28:44.940 Now that you know a little bit about cables, and you know a little bit about connectors, the next step is, you want to build a tin can waveguide antenna. 28:44.940 --> 28:46.400 That's what you all came to hear. 28:48.240 --> 28:50.620 What are the parts and tools you're going to need? 28:51.900 --> 29:02.860 You're going to need a tin can, you're going to need an end connector, you could use another microwave connector, I'm going to use my example using an end connector, the example stays the same. 29:03.960 --> 29:16.300 You're going to need a drill or a device to make a hole in the can, you're going to need a short piece of wire, you only need about one and a quarter inches, but I would say start off with about six inches so you can make a few mistakes. 29:16.960 --> 29:22.180 You're going to need a soldering iron and solder, a little flux doesn't hurt. 29:22.460 --> 29:28.000 My partner here, King Tuna Makes, and he says if you've soldered, put a little flux on it, it's going to make life a lot easier. 29:28.960 --> 29:32.840 And most importantly, you're going to need a ruler. 29:33.260 --> 29:35.280 Don't do it by line of sight. 29:36.680 --> 29:38.520 I'm sorry, by sight. 29:39.420 --> 29:40.840 Choosing a can. 29:41.260 --> 29:43.700 You can choose many different types of cans. 29:48.660 --> 29:49.620 Yes. 29:50.760 --> 29:52.600 Um, yes. 29:52.980 --> 30:08.400 King Tuna says I build better canned tuna's when I've had a shot of Jack, but we, uh, we've used coffee cans work, um, you can eat beans, baked beans cans work great, particularly anybody, anybody here from England? 30:08.840 --> 30:13.460 The baked bean cans are a lot wider there and they're much better for a cantenna. 30:13.840 --> 30:22.820 Or you can use or drink scotch at holiday time and it comes in a nice little metal commemorative can, which happens to be almost perfect for a great cantenna. 30:23.420 --> 30:25.540 Stoli also provides them. 30:28.310 --> 30:32.130 You can download plans for many of the cantennas. 30:32.130 --> 30:35.910 We're going to distribute one plan here off of the internet. 30:36.670 --> 30:41.130 Some of them will have very exact measurements of how to build it. 30:41.350 --> 30:44.010 Relax, you don't have to be that exact. 30:44.190 --> 30:48.750 You can be within 10% and still make a good cantenna. 30:51.410 --> 30:54.130 There are some dimensions which are important. 30:55.130 --> 30:57.530 You start off by having an end connector. 30:57.650 --> 30:59.150 This is an end connector. 30:59.990 --> 31:05.790 You're going to take this end connector, it has a female end on one end, and it'll have a little stub on the other side. 31:06.330 --> 31:09.750 You're going to be soldering a piece of copper wire to that. 31:09.990 --> 31:14.870 We have, in my business, we happen to use a little brass tube that we have pre-soldered. 31:14.870 --> 31:18.930 You can use a brass tube, you can use copper, you can use a copper piece of wire. 31:18.930 --> 31:20.590 They'll all work about the same. 31:23.110 --> 31:28.390 You need 1.21 inches for a radiator to be effective. 31:29.150 --> 31:29.810 Why? 31:30.590 --> 31:32.030 Let's go to the next slide, please. 31:32.570 --> 31:33.210 Okay. 31:33.230 --> 31:39.290 Now, they've just told me I only have 10 minutes because we started a little late, so I'm going to try to go briefly. 31:40.510 --> 31:50.710 The first thing to determine is based on the width of the can, the diameter of the can that you have, will determine what the length is for a wavelength. 31:50.750 --> 31:55.570 You need to position the collector one quarter wavelength from the end. 31:55.870 --> 31:57.770 That's the optimal point. 31:58.110 --> 32:00.990 That is the distance that you have to be careful on. 32:00.990 --> 32:06.730 Anywhere a little further, a little less, the antenna will still work, but you'll get lower gain. 32:07.290 --> 32:16.830 The other important measurement is what we call L over 4 here, which is the length of the radiator which is going to collect the signal. 32:16.830 --> 32:20.670 That should be as close to 1.21 inches as you can. 32:21.670 --> 32:29.250 Using a ruler to make an antenna, here's an example of one that my partner King Tuna made. 32:29.250 --> 32:31.770 It took him about 15 minutes this afternoon. 32:32.630 --> 32:37.430 This is made from a 13 inch coffee can, 13 ounce coffee can. 32:38.090 --> 32:42.430 It's not the optimal can to do it, but it shows you can do it with any can. 32:43.450 --> 32:44.850 At CVS we bought it. 32:45.530 --> 32:59.450 You take this can, we've got some plans, you can go up and there's some calculators that we'll give you that are on the internet, which based on the diameter of the can, will tell you the distance out from here that is one quarter wavelength. 33:00.590 --> 33:07.850 Cut a hole, in this case we just used a screwdriver and a mallet to cut a hole that's about 5 1⁄8 inches around. 33:08.570 --> 33:21.610 You take the radiator that you've constructed, which looks like an end connector, with a 1.21 inch piece of copper wire or brass rod, insert it, screw it down. 33:21.790 --> 33:24.370 You don't need for it to be a round connector. 33:24.370 --> 33:29.070 If you've got a square connector you can use that, you can screw it in place, you can glue it in place. 33:29.710 --> 33:32.710 The other dimensions are not going to be that important. 33:32.930 --> 33:41.070 For an optimal cantenna, you want this length to be approximately at least three quarters of a wavelength. 33:41.270 --> 33:49.630 For this particular can, which is four inches across, three quarters of a wavelength works out to be 5.15 inches. 33:49.830 --> 33:52.270 This happens to be 5.25 inches. 33:52.270 --> 33:55.350 With a 13 ounce coffee can it just happens to work well. 33:55.890 --> 34:01.390 Put it in, screw it down, that's all there is to building a cantenna. 34:01.790 --> 34:06.610 Essentially the only part that you're gonna have a problem finding is the end connector. 34:06.690 --> 34:13.230 You can get it from radio supply houses, we may even have a few left at our booth, there are plenty of places to buy them on the internet. 34:13.370 --> 34:20.490 That, a 1.21 inch radiator, and a good tin can. 34:22.630 --> 34:27.710 Take that, this particular one is four inches, 100 millimeters. 34:28.270 --> 34:28.470 I 34:33.580 --> 34:42.160 could go over the math but basically the distance that you're going to measure from here to there is going to change based on the diameter of the can. 34:45.570 --> 34:54.010 If you want, you put a pigtail on, you can then connect it up to your card. 34:54.570 --> 35:01.910 A simple cantenna like this, which took about 20 minutes to build, will give you about somewhere between 8 to 10 dB gain. 35:01.910 --> 35:03.690 We haven't fully measured this. 35:03.790 --> 35:12.250 If you're a lot more careful about the calculations, if you're a lot more careful about the length of the can, you can probably get 12 to 14 dB gain. 35:12.530 --> 35:20.790 If we make this shorter, we will get less gain, but then again we'll get a wider signal coming out of it. 35:21.290 --> 35:26.810 Some people have made them about four inches or so, and they get about a 50 degree signal breadth. 35:27.030 --> 35:32.910 If you make it about 12 inches long, you're going to drop down to about a 25 or a 30 degree signal breadth. 35:33.170 --> 35:59.610 We find it very useful to go to Home Depot, pick up a little tripod, threads a 1.25 by 20 inch, 1.25 by 20 threaded bolt, put it on there, screw it in, and now you don't have to take your coffee cup and try to measure it to get it off and left to focus it. 35:59.610 --> 36:01.550 You can put it on any camera tripod. 36:02.370 --> 36:04.950 It's really very simple to build a cantenna. 36:04.950 --> 36:07.490 Again, two calculations necessary. 36:07.770 --> 36:16.570 The length of this is 1.21, and go and find, either use the plans that we've got for working with a simple coffee can or go on the web. 36:16.570 --> 36:22.450 We've got a website where you can go to a calculator and measure this out to this 1.25 wavelength. 36:23.590 --> 36:25.050 Any questions? 36:33.950 --> 36:45.110 The optimal radiator is a trapezoid, actually a cone, but it's pretty hard to make a cone like that. 36:45.250 --> 36:49.750 So by making a rod, we end up trying to get in the middle channel. 36:54.640 --> 36:56.260 See me afterwards. 36:56.260 --> 37:04.700 What you want is a trapezoid, I think it's six millimeters at the bottom and one millimeter at the top. 37:04.700 --> 37:07.020 Again, 1.21 across. 37:07.020 --> 37:08.000 That's optimal. 37:08.000 --> 37:08.700 Yes? 37:12.460 --> 37:13.420 No. 37:14.480 --> 37:19.260 We tried it with copper, we tried it with bronze, we even tried it with aluminum. 37:19.260 --> 37:20.680 They all work well. 37:20.980 --> 37:23.180 We didn't see a significant difference. 37:24.120 --> 37:24.860 Yes. 37:41.450 --> 37:42.930 Thank you very much.