Directional Antenna at 2.4GHz

[techie]

homemade 2.4 ghz corner reflector

How can I make a directional antenna for 2.4GHz. The application is to extend the range of a 802.11 ehternet bridge. The bridge has monopole antenna and has a range of 300m. I wish to increase this range in one direction to about 1km.

Is it at all possible

 

[flatulent]

40 db antenna gain

You will need about 20 dB of antenna gain at each end. The D-Link company and others sell high gain antennas of this value. They should not have any obstructions between them like walls or buildings.

 

[Pingy]

Hi Techie,

You can make yourself the antennas, it is not difficult. A 60 cm dish, like
the ones used for TV-SAT will give you the right gain at the 2.4 GHz
frequency. Of course there are other antennas that could be used as well.

Regards

pingy

 

[OvErFlO]

I have create a dish antenna with a Vsat dish and a pringles like feed. I have buy a dish gregorian (24dB).
With this two antenna I have do 9Km with -62dB of signal... With two dish antenna it's possible a 35Km connection...

 

[FFFFFF]

look at this page :

https://www.pulsar.ch/pulsar/tonna-f9ft-antennen.htm

**broken link removed**

**broken link removed**

antennas by F9FT

6 * F

 

[flatulent]

general rules

The general rule for over the horizon smooth earth ground wave path is 20 dB more total system gain for doubling the range. For line of sight it is 6 dB.

Line of sight includes reflections from large objects like building walls and mountains although these have a reflection loss that is fixed in value for a give path.

802.11 uints have a wide variation of output power. Plug in cards for computers are 10 mW and some box units are 100 mW while the legal limit in some parts of the world is 1 W.


You can get another 10 dB improvement by cutting the bit rate back to the lowest rate.

 

[Lupin]

What about a planar array of patch antennas? You can reach a Gain of 25-30 dBi.. What do you think? Is your antenna for a WLAN application isn't it?

Regards
Lupin

 

[techie]

Thanks guys. As I mentioned, my application is purely hobby. As my office is in line of sight 1km from my home, I want to bridge the LAN there with my home PC without spending too much money. Data rate is not an issue.

Pingy & OverFlow, can you shed some light on how to make the 60cm dish, what kind cable to use from the 802.11 transciever and how to terminate it at the dish. Although I did study electromagnetic in EE, this is not my field. Any novice design examples avaialable on internet or if possible, can you give some guidance,

thanks

 

[Pingy]

Hi Techie,

A link over a 1km distance should be piece of cake. You can find
information on the web from people who made antennas for the
2.4 GHz band. Here are some examples:

h**p://www.qsl.net/ki7cx/wgfeed.htm
h**p://www.qsl.net/kc2hax/ant/feedhorn.htm
h**p://www.xyz.net/~joe/OSCAR3.html
h**p://lea.hamradio.si/~s51kq/ANTENNA.HTM
h**p://www.ultimatecharger.com/Dish_Feed.html
h**p://www.qsl.net/wk8l/

For the cable I recommend to use a good coaxial. The cable used for the
SAT-TV dishes (75 ohm) is cheap and good enough for this aplication.

Good luck

pingy

 

[techie]

Thanks a million Pingy. These look easy to make antennas. You mentioned that achieving a 1km range should be a price of cake. Do you think connecting this parabolic antenna to the following device

h**p://w*w.linksys.com/products/product.asp?grid=33&scid=36&prid=432
Linksys-Wireless ethernet bridge WET11.
will increase its range from the mentioned 300m to above 1km.

Obviously I intend to use two of these devices with two parabolic dishes.[/url]

 

[Pingy]

Hi Techie,

I had a look at the devices you tell me and they look similar to the Avaya
systems we are presently using over a 800 m distance. I am convinced
you can easily reach well over the km range with two such devices
connected to the 60 cm parabolic dishes.

Regards

pingy

 

[techie]

Pingy, you mentioned Avaya systems. Is that also for wireless networking. Becasue if you have already done building LAN bridge, probably you can also guide a better 802.11 brdge. Have a look at the

h**p://w*w.dlink.com/products/wireless/dwl810+/

Is this a better device than the WET11 I mentioned before

thanks,
techie

 

[Pingy]

Hi Techie,

Yes you are right, this type of device is twice as fast as the Avaya link
we are currently using. I didn't know about this 22 Mbits/s range of
products. Thank you for the information.

Regards

pingy

 

[techie]

Yes Pingy, this device is at 22Mbps. But do you think this is better than the Linksys wet11 as far as range is concerned. It says 400m against 300m of linksys. Frankly speed is not important. I can handle even 5mbps if range is OK.

How about the Avaya solution that you are using. Can you shed some light on that. What model did you use and how much range enhancing did you achieve. The antenna type etc. Any other practical problems here.

thanks

techie

 

[techie]

Another product from D-Link is DWL-900AP+. This being another 22Mbps product looks much better than the DWL-810+. What do you think of it.

 

[Compy]

if i use Dish antenna of digital receivers.. to send signal.. what module will i use to send signal.. LNB will be compatible for 802.11g
thanks

 

[Jerzyg]

How can I make a directional antenna for 2.4GHz. The application is to extend the range of a 802.11 ehternet bridge. The bridge has monopole antenna and has a range of 300m. I wish to increase this range in one direction to about 1km.

Is it at all possible

The simplest and chaepest test would be to place your monopole/dipole antenna in a 90 degree corner reflector. In order to keep your matching separate your monopole by 0.37λ from the vertex. This will increase your gain from around 2dBi to 10-12dBi. The bigger reflector you use the better, but reasonable size of walls should be around 1λ width and 2λ high.

Regards,
Jerzyg

 

[jallem]

try canantenna:

**broken link removed**

 

[creative_35]

Hi friends,
How do I check the gain of an antenna? I don't have a laptop. can I use wireless LAN card + wireless access point in same PC and measure (Compare) the gain of my home made antenna with netstumbler? ( I never used netstumbler before). Is there any other way to check the gain and VSWR? ( I have no equipments except a digital multi tester)