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<

printed 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: printed antenna
Posted: Fri Jun 11, 2004 2:23 pm 
 
Captain

Joined: Fri Jun 11, 2004 2:17 pm
Posts: 5
I am fairly new into antenna design as I have been mainly a RF guy for 4 years working on TX and RX circuits for cellular products and have ventured into the 2.4GHZ area now.

Question is I am trying to figure out the main advantages of having an antenna at 200ohms versus a 50ohm for 2.4Ghz.

From the tx or rx path I have a balun that converts the signal from 50ohm to 200ohm (this is from previous designer who left and i took over and he is overi n japan now). I have worked with cellular antenna and have always matched to 50ohms, just curiuos why for a 2.4GHz antenna it would be 200ohms.

any insight on starting this desing would be greatful as I am the only RF guy here and I am getting some antenna design books next week. Thanks for responses.


 
   
 
 Post subject:
Posted: Fri Jun 11, 2004 2:51 pm 
The only reason that I can come up with is... that impedance (200 ohms) is just what that specific antenna type looks like. As you know, not all antennas are 50 ohms driving impedance, infact most arent, so you have to match to them. It just turns out that some standard kinds of antennas, like monopoles have a pretty low impedance to start with and can be used in 50 ohm systems without matching. Some patch antennas can look like 200 ohms due to the physics of the antenna.

In other words, there is no advantage to having a 200 ohm termination impedance specifically, but the antenna impedance is more driven by the type antenna and what kind of performance you need from an antenna pattern point of view. Matching is often secondary.

If you have a resistive 200 ohms, then consider yourself lucky, that's an easy match.

Good luck,

Darrin


 
  
 
 Post subject: thanks
Posted: Fri Jun 11, 2004 5:50 pm 
 
Captain

Joined: Fri Jun 11, 2004 2:17 pm
Posts: 5
thanks for the insight, I had the feeling that was the reasoning, just was not sure.

I appreciate the quick response.


 
   
 
 Post subject:
Posted: Wed Jul 07, 2004 3:05 pm 
Also, just to add to the excellent comments, most antennas if not all, have reactance so the actaul impedance you are considering needs to take into account R + jX for matching to your system or calculating radiated power. If X is not minimized then radiated power is reduced. Of course there are other variables to consider in antenna design.



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