IXSigmaXI

I got some plans for a 2.4 ghz 1 watt 2 way amp and I'm planning on building it in the electrical engineering department of my school. I have a electrical engineering major and an electrical engineering professor helping me, I'm just wondering about some basics, they can definatly teach me what I need to know to make it, but I doubt they know much about wlans.

I have to connect the amp to the router some how, and I know that the router has no N connectors on it.
The D-link wireless router has 2 antennea which screw in.
I havn't decided to buy one yet, but I would definatly get one if I knew that there was a piggy back cable that converted the port on the router to an N connector cable.

if this is impossible, what are some suggestions on what router to buy and how to connect a piggy back cable to it?

of course I also need to make a big antenna for it, I was looking on one of the sites on WarDriving.com and I saw this design, http://www.saunalahti.fi/elepal/antenna1.html

It looks rather interesting and cheap to build but one thing that is confusing is the dipole element, I was wondering why it is built the way it is, does anybody have some basic instructions for making a 2.4ghz dipole, I could just try to duplicate the one on the site but I thought I'd be better off asking some people with knowledge about this sort of thing. what are the essential charactoristics of a dipole? what will make 1 dipole better than another? what will make a dipole fail?

I'd love to answer any questions about this project, especially since I don't know what questions I should be asking myself, nor problems to expect.

Thank you very much for any help!

IXSigmaXI

one other thing about N connectors
do I need a crimping tool, and how do I use it, really I don't know much about this but I am very interested

a couple close ups on existing setups would be fine
some pictures of step by step procedures would be excellent

IXSigmaXI

Huzzah for fab-corp

I've answered my own question about the D-link router by cruising on the other threads, and I found that the reverse polarity SMA to Female N will definatly work with no crimping involved.

and it seems that I'd save 20 dollars on a 50 foot lmr400 jumper cable if I bought the cable and N connectors seperately, but I still don't know quiet how to do that so be a pal, gimme some pics

-sig

agentgrn

Be very careful about just using the amp and plugging it in...the frequency band may be unlicensed, but that doesn't make you immune to FCC rules.

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-A.G.-

Thorn

This is only legal if you hold a ham radio license. Otherwise it is VERY illegal. The FCC does not play nice when you violate these laws. Keep it down to 1 watt or lower and you will be legal.

If you are tempted to try anyway and see if you can "just get away with it" I would suggest you check the FCC website posting for similar violations before proceeding. There are more every day, and the fines start at ten thousand dollars per day per offense.

BTW, before posting in the FAQ forums again. Please read the Antenna FAQ Rules. Each FAQ forum also has similar rules.

__________________
Thorn
"Read Altas Shrugged. Compare it to today. Repeat as necessary"

IXSigmaXI

TITLE 47--TELECOMMUNICATION

CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION

PART 15--RADIO FREQUENCY DEVICES--Table of Contents

Subpart A--General

Sec. 15.23 Home-built devices.

(a) Equipment authorization is not required for devices that are not
marketed, are not constructed from a kit, and are built in quantities of
five or less for personal use.
(b) It is recognized that the individual builder of home-built
equipment may not possess the means to perform the measurements for
determining compliance with the regulations. In this case, the builder
is expected to employ good engineering practices to meet the specified
technical standards to the greatest extent practicable. The provisions
of Sec. 15.5 apply to this equipment.


--------------------------------------------------------------------------------

IXSigmaXI

Beleted!

sorry about the faq business.

IXSigmaXI

now can anybody answer some of my questions?

sysadmn

Ya never know - we double-e's are pretty crafty. We used to joke that the CS people dream it up, but the engineers make it work
FAB Corp. If it exists or can be made, they'll know. Good service, good quality, great prices.
You probably don't need to make a big antenna if you're pumping 1W in unless you're going for a distance record.

This page is really a pretty good introduction to the dipole. If you don't understand it, you need a more basic knowledge. Not to be a smartass, but I don't know what you know. Do you understand frequency and wavelength? If not, start with
How Stuff Works - Radio. If so, maybe this discussion of types of antennas
or this discussion (mentions bluetooth, but the theory is the same) will help.

Dipoles are nice because they are simple and forgiving. They are just two arms (hence the "di"), each 1/4 of the wavelength. The "T" shaped FM antenna is a dipole for the (US) FM band.

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Thorn

15.23 won't cover you if you knowingly exceed the limits. You have already stated that the designed output is double the legal limit for unlicensed operation. Just get your license, and then you do this legally. You'd also learn enough theory to at least get you started on some of the basics.
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Pertaining to your questions, here's a simple explanation: A dipole is an antenna element consisting of a radiating element connected to the transmitter output and an equal length element connected to the ground or earth at the end of the transmission line. In the type of setups we are typically dealing with in 802.11b, these elements are connected to the central portion of the coax and the shield of the coax.

In order to work efficiently, the length of these elements are mathematically a function of the wavelength of the given transmitter. The closer the elements are to the given frequency's wavelength or a fraction of the wavelength, the more efficient they will function.

The Greek letter Lamda is typically used to represent wavelength, although you will see the English "L" used on some systems incapable of printing or displaying Greek letters.

Typically in antenna design, fractions of 1/4 (L/4) and 1/2 (L/2) are used, although occationally, 5/8 is also used. Quarter-wave elements are used many times to form a half-wave dipole.

Finally, on a wide frequency spread such as used for 802.11b in the ISM band, in order to obtain the best overall operation across the fully used frequency area, designs are based on the center frequency. In this case the 802.11b channels run from 2.401GHz to 2.473GHz, and the center frequency is 2.437GHz. This is also the center frequency of Channel 6, which is center channel.

For reference: At center frequency for 802.11b, the wavelength works out to be about 4.84". Therefore, a quarter-wave element is 1.21" and a half-wave is 2.42"

The equation for computing the wavelength is:
L = 3.0 * 10^8 * (1 / f) * 10^-9
where f is the frequency is GHz.

As always, I recommend the ARRL Antenna Handbook for everything you might want to know about antenna design and function.

Edit: The Lamda doesn't show on these pages, so the L is used.

__________________
Thorn
"Read Altas Shrugged. Compare it to today. Repeat as necessary"