Homepage - RF Cafe
Webmaster: Kirt Blattenberger | KB3UON | Sitemap | ©1996-2014     Visit RF Cafe on
      Menu below is just a small sample of what is here!          Visit RF Cafe on Facebook Visit RF Cafe on Twitter Visit RF Cafe on LinkedIn
Custom Search
More than 10,000 searchable pages indexed.
•−•  ••−•    −•−•  •−  ••−•  •
RF Cafe Morse Code >Hear It<

term antenna - 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: term antenna
Posted: Tue Feb 03, 2009 10:04 pm 
 
Captain
User avatar

Joined: Fri Dec 14, 2007 11:23 am
Posts: 9
Location: malaysia
hello all,

i am new with design antenna, can anyone tell me what is isolation and diversity?
only that i understand isolation mean that interaction between an antenna and its surrounding
i am confuse what correlation between isolation and diversity if we have 2 antenna in one device?
thanks.

rgds,
lee85


 
   
 
 Post subject: Re: term antenna
Posted: Wed Feb 04, 2009 4:41 am 
 
General
User avatar

Joined: Fri Feb 17, 2006 12:07 pm
Posts: 236
Location: London UK
Hi lee85
I suppose isolation is the reciprocal of coupling but I have not seen it mentioned as an antenna parameter. Coupling has 2 meanings: there is coupling between adjacent elements in an array which is either desired because it enhances either sidelobe levels or gain, and unwanted coupling that degrades performance or complicates the design process.
So far as isolation is concerned, there is a parameter called cross-polar isolation, which is the degree to which two antennas with nominally opposite polarisation still cross-couple due to imperfection. Thus if an antenna is nominally vertically polarised but with a small say -15dB of horizontal vector, then the isolation to an antenna that is hrizontally polarised will be -15dB.
Diversity takes several forms and is normally encountered when a path between antennas has a time-varying refractive index and a possibility of two or more paths: one direct and the others by reflection. Spacing two receive antennas maximises the probability that the paths to one of them will result in a vector sum that is a maximum, whilst at the other antenna the received signal has a vector sum that is a minimum, ie has faded due to out of phase vector addition. The antennas can be spaced apart vertically or horizontally (space diversity), or the polarisation can be opposite (polarisation diversity), or two different frequencies can be used (frequency diversity). The ITU-R publish recommendations how these can be implemented.

_________________
At bottom, life is all about
Sucking in and blowing out.




Posted  11/12/2012
A Disruptive Web Presence

Custom Search
Over 10,000 pages indexed! (none duped or pirated)

Read About RF Cafe
Webmaster: Kirt Blattenberger
    KB3UON

RF Cafe Software

RF Cascade Workbook
RF Cascade Workbook is a very extensive system cascaded component Excel workbook that includes the standard Gain, NF, IP2, IP3, Psat calculations, input & output VSWR, noise BW, min/max tolerance, DC power cauculations, graphing of all RF parameters, and has a graphical block diagram tool. An extensive User's Guide is also included. - Only $35.
RF system analysis including
frequency conversion & filters

RF & EE Symbols Word
RF Stencils for Visio

Product & Service Directory
Personally Selected Manufacturers
RF Cafe T-Shirts & Mugs

RF Cafe Software

Calculator Workbook
RF Workbench
Smith Chart™ for Visio
Smith Chart™ for Excel
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!)

5CCG (5th MOB): My USAF radar shop

Airplanes and Rockets: My personal hobby website

Equine Kingdom: My daughter Sally's horse riding website