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Author Topic: DAP-1522 Ext Ant .... ( a cantenna project )  (Read 20456 times)

OldTechy

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DAP-1522 Ext Ant .... ( a cantenna project )
« on: July 20, 2012, 12:16:53 AM »

Hi
DAP-1522 wave-guide (cantenna) external antennna project.

... later I will provide reasons for this project ( it's late now )

I plan to do the ext. ANT. mods  as descibed elsewhere .. with a twist ...
(stay tuned ).

as 1st, initial test, ( i.e proof of concept )

I drilled a ( ~3/8' ?) hole 1-1/3" from bottom of Coffee can (bottom ridge; MasterChef 33oz,, walmart)
 ( can is apprx . 6-1/6" O.D. and 6-3/8" high )

This drilled hole was to just-fit the "ANT-jack" end of a usb WiFi adapter ( TL-WN722N TP_Link ) from outside the can ...
...and then firmly, re-attach the ANT to the adapter's ANT-jack, inside the "CAN".

My initial readings (using in "inSSIDer" ) for this simple rig pleased me.

below are some findings from my early, baseline  tests.

(with and without the wave-guide, "cantenna" )
... best-case (steady-state)
rSSi   ( received signal strength indicator; from inSSIDer )
(smaller negative is stronger signal)
 
P - PREFERRED-AP   (max-avg value for "my Good-AP" )
I - Interfering AP's : avg-max. value of strongest interferring BAD-AP(s)
D - Dominance (P - I)  ( larger negative is better )


Antenna                  rSSi-P      rSSi-I       ( D )        note
w / cantenna        -59           -89         -30        this is really good!
w/o cantenna       -66            -85        -19
signal chg total     -7             +4         -11   
  
note      improved        atten'd     
            GOOD AP        BAD      

improved AP's signal-ratio (P - I) ; SNR: ~55%
« Last Edit: July 24, 2012, 05:51:36 PM by OldTechy »
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FurryNutz

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Re: DAP-1522 Ext Ant .... ( a cantenna project )
« Reply #1 on: July 20, 2012, 07:29:54 AM »

Please provide pics  :o
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OldTechy

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Re: DAP-1522 Ext Ant .... ( a cantenna project )
« Reply #2 on: July 20, 2012, 09:43:53 AM »

... mod: improved this table layout for 'readability' ; pixs forthcoming..

Antenna              rSSi-P     rSSi-I     ( D )     note


w / cantenna           -59         -89        -30    <=this is BIG improvment
w/o cantenna           -66         -85        -19
                        =====      =====      =====
signal chg total         -7         +4         -11   
note:                 Improved    atten'd      improved
                     'good' AP   'BAD' AP(s)   rSSi-ratio      
                                               rSNR: ~55%
« Last Edit: July 20, 2012, 12:04:13 PM by OldTechy »
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FurryNutz

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Re: DAP-1522 Ext Ant .... ( a cantenna project )
« Reply #3 on: July 20, 2012, 09:45:10 AM »

whats "atten'd"  ???
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OldTechy

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Re: DAP-1522 Ext Ant .... ( a cantenna project )
« Reply #4 on: July 20, 2012, 09:49:13 AM »

whats "atten'd"  ???
attenuated ( opposite of GAIN )
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FurryNutz

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Re: DAP-1522 Ext Ant .... ( a cantenna project )
« Reply #5 on: July 20, 2012, 09:55:54 AM »

 ;)
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OldTechy

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Re: DAP-1522 Ext Ant .... ( a cantenna project )
« Reply #6 on: July 20, 2012, 10:09:27 AM »

https://public.bay.livefilestore.com/y1pEfQsmy4H716Cf3O1ss1-PsmmRaUUkuMCu8e9gPEDxK7Sn4N5qiXWdsOiDVlWUCNj1ZBsgky3Ul3xXMfSSrQazA/100e2884s.jpg?psid=1

« Last Edit: July 20, 2012, 10:12:37 AM by OldTechy »
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FurryNutz

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Re: DAP-1522 Ext Ant .... ( a cantenna project )
« Reply #7 on: July 20, 2012, 10:17:34 AM »

Got a pic of what the connection looks like on the inside of the can?
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OldTechy

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Re: DAP-1522 Ext Ant .... ( a cantenna project )
« Reply #8 on: July 20, 2012, 10:27:09 AM »



neglected to really clean coffee residue ... he he
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OldTechy

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Re: DAP-1522 Ext Ant .... ( a cantenna project )
« Reply #9 on: July 20, 2012, 10:28:28 AM »



this experiment was all just the proof-of concept ...

Next : I am Modding the DAP-1522 to use RP-SMA ext.. ANT connections (x2) ...

then, with  1m RP-SMA extension coax cables, connect the DAP-1522
to the two (2 ) external Cantennas ( cantenni? )

QUESTION :
aligning & tuning the cantennas, is going to be problemattic.
afik: WiFi sniffer prgs only with the adpters & not an external bridge , hmm
anybody know of any software/app trick to  continuously "site-survey" monitor/update signal connextion for the DAP-1522?

« Last Edit: July 20, 2012, 10:40:01 AM by OldTechy »
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OldTechy

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Re: DAP-1522 Ext Ant .... ( a cantenna project )
« Reply #10 on: July 20, 2012, 10:30:42 AM »

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OldTechy

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Re: DAP-1522 Ext Ant .... ( a cantenna project )
« Reply #11 on: July 20, 2012, 10:41:31 AM »

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OldTechy

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Re: DAP-1522 Ext Ant .... ( a cantenna project )
« Reply #12 on: July 20, 2012, 11:53:42 AM »

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OldTechy

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Re: DAP-1522 Ext Ant .... ( a cantenna project )
« Reply #13 on: July 24, 2012, 06:22:54 PM »

update: I am awaiting delivery of the "fiddly-bits" from H.K.  (ebay) (2-wks?)
[i.e.  rp-SMA doodads :(pig-tails, antennas, 1m coax cable,  M/F jacks)]
( don't laugh, but those  prices were irresistible ... )

While waiting on the "doodads", I was planning to construct & test a double-length,coffee-Cantenna- waveguide.  So, I asked the "better-1/2" to pick-up another coffee-can. Well, the similar size can from a different grocer is ... wait for it .... cardboard.  grr.  Coffee anyone?

So, in the meantime, I'd like to ask he knowledgable viewer(s) a question.

-->  [Assuming the probe is properly positioned near the "focus"]
       Would replacing the can's flat-bottom with a suitable, parabolic-reflector,
       provide additional signal-gain for a waveguide-cantenna?
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OldTechy

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Re: DAP-1522 Ext Ant .... ( a cantenna project )
« Reply #14 on: August 02, 2012, 01:41:54 PM »

update : my coffee-cantenna  tests ...

suprisingly, my 1st attempt at a cantenna ( as reported at top of this thread)
provided my best results ( signal strengths & directivity , etc.)

other variations tested : ( unimproved on initial results )

- ANT. (probe) location [ 1.2" & 1.4" ] from bottom of coffee can
- smaller ANT ( from DIR-655)
- sgl-coffee-can with various parabolic "reflective-bottoms
   [ 1-solid bowl, 2-colander(holes), 3-strainer(mesh) ]
- dbl. length coffee-cans
- smaller can (No.3 : 4-1/4" x 7")

curious ...

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