Friday, July 4, 2008

Horizontal Polarized Omni

Horizontal Polarized Omnis are mystery for me . Anyone was seen open vertical polarized omni for wifi. Whit horizontal ones there is another story. Except slotted waveguides /these works great/ , but they are really big things.
Here is one idea for horizontal omni or “double helix antenna” :
Mast is used for reflector for for this one. Ant in the internet there is a lot of designs for spiral antenna. Difference here is that is used dual spirals. Coaxial line is hidden inside of the mast, and its look like that feeding point is on the bottom of the antenna.
One more link - there was calculator for this antenna on that treat : but now I cant find it.
Thanks to the rt_rex You can find calculator on this site : Omni Helix XLS
I hope that soon we can see some results and tests of this antenna

Stub Loaded Helix WIFI Antenna

Goggling early in the morning some time give me some very interesting results
This time is this thing - helix antenna whit reduced dimensions.
This thing have gain: 12dBi and dimensions only 165mm light and diameter of a dish 165mm
link :
Here You can find some patent info:

Curtain Quad Panel Wifi Antenna 18dbi

This looks very crazy, oddly promising 18 dbi gain.
BUT now there are more info about this, as promised by admin of the GUW forum.
Here is all info in spanish :
The author of this one is Ross Anderson and the original idea for this antenna is from 1984 year the good thing is that all the information about this one is here.
There is interesting version of this antenna build by the author. On his site he describes the how to build this panel antenna from zing fence. The original 2400mhz version is here :
The idea and the info :
Here some pictures from the em simulation from GUW site :
So as I see this, I can accept that this antenna works. On the site is said that this antenna outperform many commercial ones.
The diagram of this antenna and look from in front :

Resurrecting DWL-2100AP

I have this clone of D-link DWL-2100AP.
It worked great for a 10 mounts - after that AP begin to continually rebooting. It is not possible to upload new firmware whit tftp.
Now whit OpenWrt on fonera there is more info how the staff works whit this atheros based APs. A lot of info is available on Italian and Russian sites.
What I make to re-flash my 108mb atheros ap. PCB is clone of DWL-2100AP rev.2.

Dual-Band 2,4Ghz / 5Ghz Omni WIFI Antenna

Some time ago I needed some 5ghz antennas - this is the first thing that I bought.
Dual-band 11a/g 7/5dBi Indoor Omni Antenna from trendnet.
The papers says :
Frequency Range
802.11a: 4.9 ~ 5.875GHz802.11b/g: 2.4 ~ 2.5GHz
Linear, vertical
HPBW/ Horizontal
HPBW/ Vertical
802.11a:25° 802.11b/g: 35°
The stupid thing is that on the site specification and in pdf data sheets was said that this antenna have VERTICAL polarization, but now I can see that omnidirectional pattern came whit horizontal polarization

D-Link Ant24-1200 Sector Panel Antenna

In the test witch netstumbler - i get too low results - may be something is wrong, maybe material of pcb board is not the same
My TEST for dwl 12dbi thing something is wrong whit my ones :
this is room test - distance ~2mlinksys wap11 whit original antenna - APzydas zd1211 usb whit rpsma connector soldered and 5 cm coax soldered to antennas.various antennas tested to be able to compare result.
Second test - tv tower ~1.5 to 1.8km
Same antennas - near same ressults rubber duckie 2dbi , smc 11 clone , trend omni - original , interline 14 dbi clone and dwl 12dbi

Backfire Helix Feed

First - I never made any helix antennas, nor spirals or anything similar. Consider this as warning BUT in the HAM world spiral feeders used in dishes is something very often used.
Very simple - small spiral and reflector in front of the dish.
It looks like that in the spirals there are several modes endfire and the normal-mode. This modes are explained on the side, but more reading is needed. Also there is right and left hand rule in these antennas.
On the page is a NEC code witch may be useful to simulate this antenna.
Dimensions on the pictures are given for 2401MHz but the peak for this is around 2.3ghz so for tests whit wifi we must change dimensions a little.
If anyone have the references as PDF - do not bother to send them to me
more pics :

FAP-20 WIFI Pannel Antenna

Designed by SHAMEL
Promising gain : 20 dbi
Frequency : 2400-2480 Mhz

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