教你自制“大炮”－高增益天线

zorro

初步资料整理完毕。

[ Last edited by zorro on 2004-2-27 at 19:03 ]

zorro

How To Build A Tin Can Waveguide Antenna

for 802.11b Wireless Networks
or other 2.4GHz Applications

Got no dough for a commercial antenna? Looking for an inexpensive way to increase the range of your wireless network? A tin can waveguide antenna, or Cantenna, may be just the ticket. This design can be built for under $5 U.S. and reuses a food, juice, or other tin can.
I am not an electrical engineer, nor do I have access to any fancy test equipment. I've built some antennas that worked for me and thought I would share what I learned. I have no idea if this is safe for your radio or wireless network equipment. The risk to you and your equipment is yours.

Building your Cantenna is easy, just follow these steps.

Collect the parts
Drill or punch holes in your can to mount the probe
Assemble the probe and mount in can

[ Last edited by zorro on 2004-2-27 at 18:42 ]

zorro

Collect the parts:
You'll need:

A N-Female chassis mount connector.
Four small nuts and bolts
A bit of thick wire
A can
These vendors can supply the parts (the wire and can you provide yourself).

The Connector
A N type Female Chassis-mount connector. One side is N-female for connecting the cable from your wireless equipment, and the other side has a small brass stub for soldering on wire. These can be found at electronics stores internet suppliers (see the list below under "Connect your antenna..." If you shop around, you should be able to find these for $3-$5.

Nuts & Bolts
You'll need them just long enough to go through the connector and the can. I've used #6x1/4" stainless. If your N-connector is a screw on type, then you won't need the nuts and bolts.

Wire
You'll need about 1.25" of 12 guage copper wire. This wire will stick into the brass stub in the N-connector.
  
A Can
This is the fun part. You're looking for a can between about 3" and 3 2/3" in diameter. The size doesn't have to be exact. I made a good antenna with a Nalley's "Big Chunk" Beef Stew can that was 3.87" in diameter. Others have reported good results with big 39oz. coffee cans that are 6" in diameter. The pringles can is really too small for good performance, however. Try to get as long a can as possible. The old fashioned fruit juice cans should work well

[ Last edited by zorro on 2004-2-27 at 18:25 ]

ezhang

快翻译成中文

zorro

先看看原文，然后再翻译过来。

zorro

Drill or punch holes in your can to mount the probe
The N-connector assembly will mount in the side of your can. You need to put holes in the right place to mount the connector. The placement of the hole and connect is very important. It's location is derived from formulas that use the frequency that the antenna will operate at and the can diameter. To make life easy on you, here's a calculator to figure it out for you.

Enter the diameter of your can above and click on the calculate button. 802.11b networking equipment operates at a range of frequencies from 2.412 GHz to 2.462 GHz. Ideally, with your can size, the TE11 cut-off frequency should be lower than 2.412 and the TM01 cut-off should be higher than 2.462. It would be good, also, if your can is longer than the 3/4 Guide Wavelength. If your can is a little off in length or diameter, don't despair, experimentation is fun!

You want to mark the location on the can where you will put the hole for the connector. The 1/4 Guide Wavelength number tells you how far up from the bottom metal end of the can to put the center of the hole. Open only one end of your can, eat the contents, and give it a good washing. You'll probably want to remove the label too. Use a ruler to measure up from the closed end 1/4 Guide Wavelength and mark the can with a dot.

If you've got a drill, select a bit that matches the size of the center of your connector. You may want to start with a small bit and work the hole larger and larger. You could even start with a hammer and nail, then use drill bits. If you don't have a drill, start with a nail hole and use a file to get the hole to the required size. If you're using a bolt on connector, make four more holes for the bolts - you can use the connector as a drilling guide.


Click on image to enlarge
Assemble the probe and mount in can
Now you'll need that bit of wire. You'll need a soldering iron or a friend with one as well. Cut the wire so that when it is stuck in the connector as shown, the total length of both the brass tube and wire sticking out past the connector is 1.21". Get as close to this length as you can.

When you've got your wire correctly sized, solder it into the connector keeping it as straight and upright as you can. When it's cooled, bolt or screw the assembly into your can. Put the heads of the bolts inside the can and the nuts on the outside to minimize the obstructions in your antenna. Your Done!

Connect your antenna to your wireless card or access point
To use your cantenna, you'll need a special cable commonly called a "Pig Tail". The pig tail connects your wireless card or access point to you antenna. One end of the cable will have a "N" Male connector (just right for connecting your your cantenna), while the other end will have a connector appropriate to your card or access point. For a good picture of a pig tail, take a look at:
http://www.seattlewireless.net/index.cgi?PigTail

You'll want to have a wireless NIC or access point with an external antenna connector. Otherwise, you may have to hack into the one you have to hook up the cable. I wouldn't recommend this unless you're good with a soldering iron and electronics. For this reason, I like the Agere Orinoco cards which have a nice antenna connector. Pig Tails can be hand made if you have the right tools, but it's probably easier to get a pre-made one. Try:

zorro

http://www.fab-corp.com
http://www.hyperlinktech.com
http://www.antennasystems.com
Hook up your cable, point the antenna at a friend's, and see how far you can stretch you network. Be sure to let me know how it works.

This antenna has linear polarization. That means that how you rotate the antenna will affect the strength of your signal. Usually, you will want to put the connection straight down, but experiment with rotating the can while watching the signal strength on your PC to get the best performance.

zorro

（2）
In my efforts to add the words "wireless savvy" to my network admin resume, I've been reading books and web pages on radio propagation, antenna theory and design, and building wireless networks with 802.11. One of the first things that got me excited was the Pringles Can Antenna.  Published on the internet and in a fine book by Rob Flickenger, the net admin for O'Reilly, this design for a do-it-yourself, VERY inexpensive antenna made from a recycled junkfood container is as cool as the other side of the pillow.  It seems that everyone is building and using these.  The various community wireless network groups all talk about them and folks are reporting that they do the job.

A friend of mine built his before me and looking at his finished antenna got me excited to understand the theory of how it works. Reviewing his plan, I came up with different spacing that he Rob did.  To see if I could improve upon the design, I built mine with corrected spacing.  While waiting for some wireless equipment to come in, I started looking for my next antenna project.  Oddly, the more I studied, the less I understood.  There seems to be quite a bit of confusion on how the Pringles antenna works and what design category it falls under.  The inner lining of a Pringles can looks metallic, but my tests show it not to be. The Pringles Antenna design, and some designs that pre-date it, seem to treat it as though it were metallic.  While folks are calling it a Yagi-Uda style antenna, the design of the driven element in the Pringles can antenna looks like a Waveguide style design.

zorro

Waveguide antennas don't use the director assembly (the washery bits), and therefore are much simpler to build. An old tin can of the right size, about $5 in parts and 10 minutes of time are all that are needed. The math for computing correct sizing of the components in a waveguide antenna is simple. Formulas in hand, I started searching my cupboards for tin cans that fit the spec. I found myself staring at the products on the canned food aisle at the grocery store. I even went so far as going grocery shopping with a tape measure. "No no, this spaghetti sauce looks much better. It's about three quarters of a wavelength in diameter, hon!"

[ Last edited by zorro on 2004-2-27 at 18:40 ]

zorro

What the huh?  On Feb 11th, Rob, posted an article on his newest homebrew antenna - a tin can waveguide! Rob used a large, 39oz. coffee can and placed a quarter wavelength driven element a quarter wavelength from the back of the can. He reported good results - even better than the Pringles can design used by so many. For the antennas I was building, I was using different measurements based on the antenna design material I had been reading. Now I'm a late entry into this wireless stuff and the experts are going a different way than me. It's time to benchmark.

[ Last edited by zorro on 2004-2-27 at 18:40 ]

zorro

The Shootout
My plan was to get relative performance measurements for various designs (including mine) of homebrew antennas for 802.11b wireless networks. To do this, I setup a wireless link and changed only the antenna- recording each antennas' performance under identical conditions. I didn't compare them to a commercial directional antenna as my only one has a male connector and I don't have the right cable to hook it up yet. The contestants were (click on each for design specifications).

[ Last edited by zorro on 2004-2-27 at 18:41 ]

zorro

The Performance Summary
The results surprised me! In our test, the Flickenger Pringles can did a little better than my modified Pringles design. Both did no better than the Lucent omnidirectional. Now this is just on raw signal strength, noise rejection due to directivity still makes a directional antenna a better choice for some uses even if there is no gain benefit. The waveguides all soundly trounced the Pringles can designs. I mean they stomped them into the ground on signal strength - as much as 9 dBm better. Every three dB is a doubling in power - that's three doublings (8x increase)!

Of the waveguides, the Nalley's "Big Chunk" took top marks. It was followed by the Hunts Pasta Sauce, my modified coffee can, and the Flickenger coffee can in that order. My three waveguide designs, which utilized the correct theoretical spacing, out performed the Flickenger Yuban coffee can handily. It seems that the design formulas for the waveguide design made a sizeable difference in performance. In the yagis, it didn't matter much. This could be because neither Rob's nor my designs are anywhere near right for optimum performance for a Yagi. I've decided that Yagi design is not for the timid or non-radio-expert.

With these results, I'm convinced that the waveguide design is the way to go for cheap wireless networking. The performance is good, the cost is very low and the skill required is minimal. If you can eat a big can of stew, you can make a high performance antenna.

[ Last edited by zorro on 2004-2-27 at 18:59 ]

zorro

http://www.qsl.net/n1bwt/contents.htm

over

[ Last edited by zorro on 2004-2-27 at 19:01 ]

格式化熊

后面那个大锅能不能自己做

davi

这感觉和卫星得ku 头原理一样,只是嘿嘿,内部口只用一个线怕怕,一般ku头好像是两根线嘿嘿,这个技术有待挖掘

qunsl

好资料！哪位能给翻译一下，谢谢！

Hans

看图就能明白 了吧？不用什么翻译

相当于自己做了个高频头，然后用锅集中信号于桶内的天线，我觉得可以用锅状物代替，未必是卫星天线的锅，不知道行不行？

dlm9001

会不会招雷劈

qunsl

QUOTE:

Originally posted by Hans at 2004-10-23 08:33 AM:
看图就能明白 了吧？不用什么翻译

相当于自己做了个高频头，然后用锅集中信号于桶内的天线，我觉得可以用锅状物代替，未必是卫星天线的锅，不知道行不行？

制作的关键是尺寸参数的精确，图上没有！
做好馈源后可以买一口铝锅，找对焦点放置好馈源就行，我觉得10km应该没有问题。

拂晓

QUOTE:

Originally posted by qunsl at 2004-10-23 09:50 AM:


制作的关键是尺寸参数的精确，图上没有！
做好馈源后可以买一口铝锅，找对焦点放置好馈源就行，我觉得10km应该没有问题。

大的铁炒锅，物美价廉，找角铁焊上个架子，先用防锈漆刷一下，再用白漆刷一下，50元即可搞定

myring

都是牛人..PF

ld680920

锅只起到聚集的作用，增加天线的接收和发射的距离，关键还是天线的制作

cation

馈线和这玩意在哪买 多少钱

zxcvbasdfg1

这个接头可以用BNC接头代替^-^

pangzi

QUOTE:

原帖由 cation 于 2005-1-15 16:18 发表
馈线和这玩意在哪买 多少钱

^_^，偶就是卖射频接头、馈线等所有射频附件的。

ysh_fai

高！简直是太高了！！

Kwongwo

昨晚做的

kokdulon

楼上的效果如何？

you_xi

果然，都是恐怖分子！！！

zoefly

这样。。。还算无线的吗？