Custom Search

More than 10,000 searchable pages indexed.

Greetings: There is so much good stuff on RF Cafe that there is no way to list or link to all of it here. Please use the Search box or the Site Map to find what you want - there is a good chance I have it. Thanks!

•−•  ••−•    −•−•  •−  ••−•  •
RF Cafe Morse Code >Hear It<
Job Board
About RF Cafe™
Copyright 1999-2015

[sleeve colinear ant] Guess its freq and its gain - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.

 Post subject: [sleeve colinear ant] Guess its freq and its gain
Posted: Mon Jan 30, 2006 12:16 pm 
Hello there!

I'd like to ask you a riddle. I bought this antenna on eBay and it is sensed to work in the 2.4GHz band (wifi). But as its performance was really poor, I dismantled it.
Its design is based on the so-called sleeve colinear antenna, like the one I found on the net :

I mesured the different elements:
section (2 tubes + empty space): 90.8mm
space between sections: 1mm washer
space between tubes: 34mm
10 sections
outer tube diam: 28,4mm (no dielectric filled, air only)
inner tube diam: ~28mm
top whip: 41mm
coax diameter: 3.8mm

I guess the oscillation starts from the bottom tube. But what parts do radiate: the tubes or the inner coax?

Have you found its fundamental frequency? I'm longing for your answers...

Thanks, /Lapi.

PS: does anybody know how to model this kind of antenna in 4nec2? Especially for the tube and coax. I'm quite newbie at this software.

Posted  11/12/2012

Your RF Cafe
Progenitor & Webmaster

Click here to read about RF CafeKirt Blattenberger… single-handedly redefining what an engineering website should be.

View the YouTube RF Cafe Intro Video Carpe Diem!
(Seize the Day!)

5th MOB: My USAF radar shop

Airplanes and Rockets: My personal hobby website

Equine Kingdom: My daughter Sally's horse riding website