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Easy Homemade 2.4 Ghz Omni Antenna - Comments


commentSuper !!!!!!!!!!!!!!!!!
get the more powerful antenna it is necessary to add the segments such long ?
Posted 22 Jan 2005 by Andris
commentRE: Super !!!!!!!!!!!!!!!!!
Yes, then more segments you add, the higher the antenna gain, though the increase is not linear i.e. doubling the number of segments will not double the gain.
Posted 25 Jan 2005 by Bob
commentuse a wire stripper!
Make your life easier and get a cleaner result- use a
wire stripper to make those cuts. just set it (or choose the
notch) that corresponds to the central wire's gauge.

Note the proper way to use a wire stripper is to grip
lightly on the insulation and rotate the stripper around
to get a clean undeformed cut. Have fun!
Posted 2 Feb 2005 by stuart kreitman
commentWireless cctv
Do you think this homemade antenna would work on a 2.4 Ghz cctv . The cctv I have claims to only transmmit over a distance of 100 metres . I need to transmit over a distance of 130 meters . Your advice would be greatly appreciated .
Posted 25 Apr 2005 by Martin O'Donnell
commentRE: Wireless cctv
If the 2.4Ghz CCTV camera has a detachable antenna, then you should be able to replace it with a homemade one.
Posted 27 Apr 2005 by Bob
commentThe perfect OMNI Antenna.
Hello all,
As you can read in this article the only variable factor is the V-factor. (Velocity factor of a cable)
We find a very sheep and easy way to create your own coax with a V-factor > 0,9.
1) take a coper pipe of 10 mm s=1 and cut pieces of L=53mm
2) take two blank coper wires of 2mm with the length of your antenna. (16x53mm)
3) take 16 pieces of pertinax 2mm thickness and drill two holes in it of 2mm. Center distance 6mm. (centred)
4) the work preparation is done now. Start to solder things together and you will see, you never had an OMNI like this one.
Posted 31 May 2005 by Ed van den Enden
commentG4 powerbook
may sound silly but how would i use this on a mac g4 powerbook
Posted 9 Jan 2006 by matt Thompson
commentRE: G4 powerbook
If your powerbook (or wireless card) doesn't have an external antenna, then you can't use an external antenna on it(homemade or otherwise).
Posted 10 Jan 2006 by Bob
I liked this homemade 2.4 Ghz omni antenna.

What must be the diameter of cable????
What is the gain of this antenna (in dbi)???
Posted 22 Jan 2006 by Orest
commentRE: Gain???
RG213 Cable in 10mm diameter, so antenna will fit in a 20mm tube.

Gain is between 5 and 8db depending on construction etc.
Posted 23 Jan 2006 by Bob
commentdb and dbi???
But what is the difference between gain in "db" and "dbi"????
Usually I say gain in "dbi".

Tommorow I made this antenna with 10 elements. It was easy.
And I want to ask you, are there some programm, which calculate the gain of antenna???
Posted 24 Jan 2006 by Orest
comment2.4 GHZ antenna
Re your 2.4ghz cctv camera, you say it will increase the distance it will transmit. but I need it to receive a better picture(through thick walls). is it the same thing?. and why does the length af cable to the connector(SMA male) not seem to matter.
Posted 25 Jan 2006 by Darren
commentRe: The perfect OMNI Antenna.
Can someone enlighten me what pertinax is, I'm not native English speaker and can’t figure it out what it actually means ?
Posted 1 Feb 2006 by Marek Kassur
commentType of cable??
What type of cable to connect from this antenna to AP or network card..... ?
Posted 5 Feb 2006 by Nik Din
commentRE: Type of cable??
Use RG-213 or LMR-400 cable, the thicker and shorter the cable, the lower the signal loss due to cabling. Ideally you want the AP as close to the antenna as possible. You will probably need to connect the cable to the AP with a short pigtail (available from the AP manufacturer) that converts from N-Type connectors to whatever connector is on your AP.
Posted 6 Feb 2006 by Bob
commentGain and DBI
Just finished building the antenna, used RG213. This is 50 ohm impedence, gain appears to be 4-6 dB over a simple vertical antenna.

dBi refers to the theoretical gain of an antenna over a single point radiator (isotrophic). Pretty good design.
Posted 6 Feb 2006 by Glen
commentRe: The perfect OMNI Antenna.
Hi, Ed van den Enden,

Can you explain your "OMNI like no other" a little better. I am very interested. I can't quite put it together.
Posted 13 Feb 2006 by TJ
commentHelp LMR400
for the RBG213 the leght of cuttings each piece is 37+6+6+1 but how do I get the exact lenght of cuttings for lmr400, I hav calculate 1/2 wavelength for lmr400 and it's 52.1mm, is there sam calculation for the cuttings or the 3.5mm (40.5 - 37=3.5mm) is for all cables??
Posted 22 Feb 2006 by munge
Make as many ½ wave elements as needed for the gain you desire. 4 elements = approximately 3.5 dBd, 8 elements = 6 dBd, 18 elements = 9 dBd, and 21 elements = 10 dBd. In addition to the ½ wave elements, you need a ¼ wave element and a ¼ wave whip for the top of the antenna. The whip is cut to a true ¼ wavelength (no velocity factor correction) and is made out of number 12 wire or 1/8" brass rod. Vertical beam downtilt can also be applied into the calculation and construction of the antenna.
Posted 27 Feb 2006 by Bee
Well.... I have to say the design is excellent. I am comparing it to the built-in antenna on my laptop (ECS A530, which has a very poor signal strength), with a monopole standard antenna (simple, but well calculated), and with a D-Link DWL G122 USB adapter, mounted through its cradle at about 1M from the laptop.

The gain with the homemade monopole antenna was about 3db.

The D-Link gained about 10db compared with the built-in antenna on my laptop.

The gain with the Omni is about 15db!

The Omni has even better signal than a D-Link DWL G122 USB adapter (about 5db higher signal, approximately as the disposition of the rooms in my house is somewhat weird, so sometimes they perform the same and sometimes the Omni much better.). So really, I only have to say THANKS for this.

The signal to noise ratio keeps the same (as the signal increases, also the noise)

By the way, I am using Network Stumbler 0.4.0 to scan the network and seek detailed info on signal/noise ratio.

For more info, I am using a BNC connector (yes, it's big), and standard cable (meaning, not from any particular brand).

Thanks again... Now I have connectivity in every room :)
Bets regards
Posted 12 Mar 2006 by Sebastian
comment2 Tuna-can Bow-ties as Back-to-Back?
Could 2 of these, back-to-back, be used to extend a wireless routers' range by 1/2 mile?
Posted 17 Mar 2006 by J.L. Frusha
commentRE: 2 Tuna-can Bow-ties as Back-to-Back?
I don't know what the gain of these is, but 1/2 a mile isn't that far, so if you have line-of-sight then you should be able to get some sort of wireless link going.
Posted 18 Mar 2006 by Bob
commentHow long should be a 12dbi antenna?
Posted 22 Mar 2006 by Serge
commentRE: How long should be a 12dbi antenna?
Probably around 32 elements.
Posted 23 Mar 2006 by Bob
commentCalculating dB and elements
Is there any formula to calculate how many elements for X dB?

supouse that I want to create 16 dBi
Posted 2 Apr 2006 by ROBERT HANSON
commentRE: Calculating dB and elements
The referenced guerrilla.net design details the number of segments required for different gains.
Posted 2 Apr 2006 by Bob
commentRG-213 vs RG-214
is that okay to use RG-214? because I couldn't find RG-213 in my town.
Posted 3 Apr 2006 by ROBERT HANSON
commentRE: RG-213 vs RG-214
Not sure about that, although the impedence and velolcity factors look the same, the core and shielding appear to be a different material to RG-213.

Why not try it, and let us know how it works out.
Posted 9 Apr 2006 by Bob
commentDesign Question
Guerilla omni design connects the center at the top, than adds the 2 quarter waves @ the top(one adjusted one true).
This one does not.
How is the design affected by this?
Posted 14 Apr 2006 by cG
commentRE: Design Question
I don't know the answer to that, I based the omni design mainly on the rason.org design, with length calculations from the guerrilla.net design.
Posted 14 Apr 2006 by Bob
commenth1000 cable VF ??
I have H1000 cable, how can i mesure its velocity factor?
Anyway can i really use this cable?
Posted 14 Apr 2006 by r1im
commentRE: h1000 cable VF ??
I don't know how to measure the velocity factor, but I'm sure it must be listed somewhere. Most cable supplies list the velocity factor along with the impedance. You just need find one for your cable.
Posted 15 Apr 2006 by Bob
commentRE: Calculating dB and elements
It seems that guerrilla.net cannot be accessed. Is the link correct or dead already?
Posted 17 Apr 2006 by ROBERT HANSON
commentRE: RE: Calculating dB and elements
The guerrilla.net site does seem to be unavailable quite often unfortunately, so, there are links to cached copies of the guerrilla.net articles on the "Wi-Fi Pages and links" page.
Posted 18 Apr 2006 by Bob
commentRE: RG-213 vs RG-214
Finally, I bought 2 meters RG-214 cable and it works! according to some books, RG-214 has lower loss signal than RG-213. Please try it! It really works. It only took $1.2 for a meter.
Posted 18 Apr 2006 by ROBERT HANSON
commentHow it works?
Could somebody tell me where can I find information how this antenna works? because I'm a student of electrical engineering. I'm very impress with this design but I cannot find in any books about this design. Please tell me where this design came from :-) Thanks!
Posted 19 Apr 2006 by ROBERT HANSON
commentandrew cable heliax 50 ohm 1/2
according to the official website http://www.andrew.com/search/BN_HJ4-50.aspx ,the velocity percentage are 91.00%, so the velocity are 0.91, so how can i get the 1/2 wave and 1/4 wave. thanks.
Posted 20 Apr 2006 by chong chong choon
commentRE: How it works?
Most of the information on antenna design is related to HAM radio antenna, it just needs to be scaled for the 2.4Ghz frequency.
Posted 20 Apr 2006 by Bob
commentRE: andrew cable heliax 50 ohm 1/2
Simply plug your velocity-factor into the equation where the 1/2 wave-length is calculated.
Posted 25 Apr 2006 by Bob
commentInfo on Gain and power
My AP has a transmit power of 18dbm. If I build an antenna with a lot of gain, I'm gonna jam my brain if I stay near the AP?? What is the max gain of the antenna in order to mantain a safe output power from the AP??
maybe this is an idiot question, sorry....
Posted 30 Apr 2006 by Marco
commentRE: Info on Gain and power
It actually depends on where you live. In Europe the maximum output dBm is 20 (in the US it's 27dBm I believe), which while quite low, it is probably best to go with a conservative value. While I'm not aware of any research linking wireless kit to brain damage, it does operate on microwave frequencies, so I'd always recommend against running an over-power rig if you are going to be sitting next to it.
Posted 3 May 2006 by Bob
commentRG-213 Loss
Could somebody please tell me how much loss will I get for each meter of RG 213 I use from the antenna to my PC? OR should i use any other cable instead? I mean, cheap, readily available cable....
Posted 10 May 2006 by jcane86
commentRE: RG-213 Loss
Use the "Cable Loss Calculator" listed on the "Wifi pages and links" page
Posted 10 May 2006 by Bob
commentRG 213 vs RG 8
is that okay to use RG-8? because I couldn't find RG-213 in my town. beside velocity factor of RG-8 is 0.66 same as RG-213, impedance is 50
Posted 10 May 2006 by Salsabil
commentRE: RG 213 vs RG 8
I can't see much difference between RG8 and RG213, so given how cheap a meter of cable is, why not try it and let us know if it works.
Posted 11 May 2006 by Bob
comment2.40 Ghz omi antenna
will this antenna work if you pluged it in to the router it self
EG the linksys wirless G, it has 2 antenna on the unit, can i build two of thease antenna and installthem on the router?
Posted 14 May 2006 by mark
commentRE: 2.40 Ghz omi antenna
Yes that should work just as well
Posted 15 May 2006 by Bob
I just built a 21 elements antenna without luck, Using RG58a/u cable. This cable have same velocity factor but more
Line loss, I missing something I don't know, I'd like to see more Pictures of this antenna to compared.
Posted 16 May 2006 by DaveM
commentNo. of elements
can someone explain it to me how numbers of elements influence to antena.If I want to bild a omni 2.4GHz 18 db how many of elements I have to cut,using tr- 165 cable.
Posted 22 May 2006 by Zix
commentRE: No. of elements
If you want an 18db antenna I think you would be better off with a yagi or parabolic antenna than an omni. I don't even know of any commerial omni antenna that go above 14db.
Posted 22 May 2006 by Bob
can i fix this on my linksys wrt54gs

replacing the antenna on my pci card gave a gain of 10%using a commercial antenna,my current signal is 41% at a distance of twenty feet three walls(bathroom) in between what antenna can u recommend
Posted 22 May 2006 by Mantis
commentRE: Ap
You can fix this antenna to anything that has an antenna connector, or detachable antenna. You just need to get the right connector.

If you are already getting 41% signal strength, then that sounds like you already have a good stable connection. You'll only get 100% if the pc is right next to the AP, so as long as the wireless connection speed is faster than your internet connection speed then it sounds like it is already working ok.
Posted 22 May 2006 by Bob
comment3dB beam degree
great.. but no say about pattern . please what about its 3dB beamwidth and can it use for transmitting?
are its polarity vertical?
Posted 23 May 2006 by ali miran
comment4 sector for homemade antena
Is that okay if I make this homemade antena with 4 sector?
because your article explain about the homemade antena with 8 sector only.
Posted 4 Jul 2006 by Salsabil
commentA homemate 15dBi
I think it need 40 element to built a 15dBi gain home home antenna 31mm+(40 time on 40.5mm) = 1651mm( 165.1 CM )
and i saw a D-Link Ant24-1500 (15dBi Omni Antenna) that have 165 cm (length)

Posted 4 Jul 2006 by sky
commenthome made omni
I am really impressed to see the omni design is excellent. One question poking
Into my mind how I connect the omni with my laptop/wireless switch.plz draw
A picture for better understands. Can I use RG500 cable for omni elements.
If u reply I’ll be grateful to u . thank you
Posted 17 Jul 2006 by krishnendu deb
commentVelocity factor
Thanks for a great site with a very good description. I will not be surprised if making the site has actually taken a lot longer than making the antenna itself.

When you calculate the distances between the sectors, is it then correct to assume a velocity factor of 0.66 for that part (3 mm) in open air? Without being any kind of expert or professor, I would believe the velocity factor for that tiny part is actually about 0.95. Likewise, would I assume the whip too, being placed in open air should be 0.95% of a 1/4 wavelength or 29.17 mm.

If I'm right about this observations I think the sector dimensions should rather be 38.5 mm coax and 3 mm spacing for RG-213 with a velocity factor of 0.66.

1/2 wavelength at 1.00 velocity = 299792458 / 2441000 / 2 mm = 61.41 mm. 38.5 mm cable at 0.66 velocity will "use" 38.5 / 0.66 = 58.33 mm of this and the remaining 3.08 mm makes a spacing of 2.93 mm if the velocity factor for the part that makes up the spacing is in fact 0.95.

I found somewhere a site, which I can't find again, where someone with access to the instruments I don't have, had determined the resonanse was at a higher frequency even though he thought he had been pretty accurate constructing the antenna. Have I by any chance found a possible explanation for his observations?
Posted 19 Jul 2006 by Steen Brisson
commentRE: 4 sector for homemade antena
You can make it with as many segments as you like
Posted 22 Jul 2006 by Bob
commentdidnt work
i made one with 38 sectors and didnt get expected resoults.... i also made other one with 8 elements, i have been very acurate and same resoult... what could it be? what polarization the wave has? connector problem? what is the tolerance for it sector alignament?
Posted 24 Jul 2006 by marcelo
commentRE: didnt work
I guess there are two possible reasons for this, either the cable you are using doesn't have the expected velocity factor (I've had reports of some cable labelled RG-213 not having 0.66 velocity factor), or the wireless kit you are connecting to is overly sensitive to the lack of decoupler in the design.

Also I'd always suggest you try no more than an 8 element antenna first, before moving on to building a much larger one.
Posted 26 Jul 2006 by Bob
commentDon't worked proprly
i maked it with 8 sector but dont worked properly --- signal strength = 58% but with 0.2dbi Omni antenna i have 98% signal with 100% quality !!!!!!!??????
Posted 27 Jul 2006 by Pouya
commentVery Good
Very Good omni
Posted 29 Aug 2006 by Ernani Junior
Wow.Its work. :)
Posted 13 Oct 2006 by Roland
commentantenna 20dbi
hi, I was wondering If I could re-design this antenna into a 2-meter, or even 3-meter length? would this help the signal in any way... I live a fair bit off from a friend of mine who lives in a broad-band enabled zone. i am 10km out of range and need something that is stronger than 6dbi..14dbi would be average, but, 20dbi is my aim?
Posted 23 Jan 2007 by Sasha Inkerman
commentRE: antenna 20dbi
For 14 or 20db you really want a directional yagi or plate antenna, not an omni.
Posted 24 Jan 2007 by Bob

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