estqwerty’s wifi antennas

Are You remember this one : http://www.digdice.com/?p=138

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 :

http://www.guw.cl/sitio/index.php?option=com_content&task=view&id=110&Itemid=36

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 : http://home.comcast.net/~ross_anderson/2400MHzAntenna.htm

The idea and the info : http://home.comcast.net/~ross_anderson/CurtainQuad.htm

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 :

More pictures of this antenna build and tested for 1296Mhz and 2400mhz :

Interesting about this is the using of speaker wire for matching transformer :

“… Solder a 1+ inch piece of speaker wire to the N connector. One wire goes to the center pin; the other wire to the outside part of the connector. I drilled a small hole in the connector flange for the wire to be inserted into and soldered in place. Leave about 3/4 inch of insulation on the speaker wire (as measured where the two wires are together). This is the transformer, transforming the antenna impedance to about 50 ohms.”

There is also PDF tutorial on the GUW site : guw panel 18dbi.pdf

So this is promising design which I should test soon too. Will be interesting to find out will this design works if it is printed on PCB?

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.

http://members.cox.net/nx7u/ao40/backfire/backfire.htm

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 :

Alford Slot - Horizontal Omnidirectional Antenna working on HAM band - somewhere around 2.3ghz or 13cm.

Whit several words what is Alford Slot : this is circular pipe whit ONE LONG slot on it, feed by coax line coming from inside the tube.

Here is some photos :

note pics are for lower frequency - typically for 1200Mhz, second shows that for low band this antenna can be made even from wire

The tutorial how to make this antenna is on this site : http://www.g8ajn.tv/23cms.htm and http://www.k5rmg.org/Alford-slot.html

Interesting about this antenna :

Omnidirectional paten

Horizontal polarization

Physically its circular - for me its important omni antenna to be circular - do not ask

Interesting feeding point of slot.

The design of this antenna is based on several tables or ready pre-calculated values.

Here is some pictures from www.g8ajn.tv

cutting the slot and ready feed points

Here is the interesting part - building of the feeding point I was really surprised :

Only this is for separate post ! This showing how to make impedance matching directly whit coax ! So on this on the last picture coax line is impedance matched.

Next is connecting coax to the slot, second picture is fine tunning, and the third is preparing for mounting. Tunning is made by extension of the slot.

Go on the sites shown up and read the instructions for building this ones You may find thing that I missed.

Wow ! It’s a surprise for me to see that helical antennas are working so good on 5ghz to 6ghz band. Here is a company that selling them http://www.q-par.com/products/helical-antennas/5-6-ghz-helical-antenna

GAIN ~10 to 11.5 dBic by specification -who knows

So if You like to try 5ghz wireless links, You may try helical antennas . I’ll be waiting for results if someone try to build and test this.

Here is the picture of one of this - nothing unusual really: