Electronics World articles Popular Electronics articles QST articles Radio & TV News articles Radio-Craft articles Radio-Electronics articles Short Wave Craft articles Wireless World articles Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs LinkedIn Crosswords Engineering Humor Kirt's Cogitations RF Engineering Quizzes Notable Quotes Calculators Education Engineering Magazine Articles Engineering software RF Cafe Archives RF Cascade Workbook 2018 RF Symbols for Visio - Word Advertising RF Cafe Forums Magazine Sponsor RF Cafe RF Electronics Symbols for Visio RF Electronics Symbols for Office Word RF Electronics Stencils for Visio Sponsor Links Saturday Evening Post NEETS EW Radar Handbook Microwave Museum About RF Cafe Aegis Power Systems Anritsu Alliance Test Equipment Amplifier Solutions Anatech Electronics Axiom Test Equipment Berkeley Nucleonics Bittele Centric RF Conduct RF Copper Mountain Technologies Empower RF everything RF Exodus Advanced Communications Innovative Power Products ISOTEC KR Filters Lotus Systems PCB Directory Rigol RF Superstore San Francisco Circuits Reactel RFCT TotalTemp Technologies Triad RF Systems Windfreak Technologies Withwave LadyBug Technologies Wireless Telecom Group Sponsorship Rates RF Cafe Software Resources Vintage Magazines Thank you for visiting RF Cafe!
Exodus Advanced Communications Best in Class RF Amplifier SSPAs

Most sensitive part of antenna? - RF Cafe Forums

RF Cafe Forums closed its virtual doors in 2010 mainly due to other social media platforms dominating public commenting venues. RF Cafe Forums began sometime around August of 2003 and was quite well-attended for many years. By 2010, Facebook and Twitter were overwhelmingly dominating online personal interaction, and RF Cafe Forums activity dropped off precipitously. Regardless, there are still lots of great posts in the archive that ware worth looking at. Below are the old forum threads, including responses to the original posts.

NOTICE: The original RF Cafe Forum is available again for reading, and the new RF Cafe Blog is an active board.

-- Amateur Radio

-- Anecdotes, Gripes, & Humor

-- Antennas

-- CAE, CAD, & Software

-- Circuits & Components

-- Employment & Interviews

-- Miscellany

-- Swap Shop

-- Systems

-- Test & Measurement

-- Webmaster

James King
 Post subject: Most sensitive part of antenna?
Posted: Fri Jun 20, 2008 9:02 pm 
 
Lieutenant
User avatar

Joined: Sun Aug 31, 2003 3:20 pm

Posts: 3

Location: Midwest

If I have say a 2.4 GHz 1/4-wave antenna mounted on a metal case and need to attach a metal clip-on thingy to it (a small plastic flag with a metal clip), is it least intrusive to attach it at the bottom, middle top? Please exlpain in your answer why you say so. Thanks guys.

JK


 
   
 
nubbage
 Post subject:
Posted: Mon Jun 23, 2008 6:39 am 
 
General
User avatar

Joined: Fri Feb 17, 2006 12:07 pm

Posts: 218

Location: London UK

Hi James

A quarter wave antenna with a low impedance at the equipment end, normally 50 ohms, will have a high impedance a quarter wave away ie at the outer end.

High impedance parts of an antenna are always the most sensitive to nearby metal object, because capacitive coupling occurs at these points even due to very small stray capacitance, as in the case of a metal clip.

A teflon or better a foam plastic clip, would probably have least impact on performance. A metal clip would be disastrous, IMHO.


 
   
 
nubbage
 Post subject:
Posted: Mon Jun 23, 2008 6:42 am 
 
General
User avatar

Joined: Fri Feb 17, 2006 12:07 pm

Posts: 218

Location: London UK

As usual, I read the question after giving the answer.

A metal clip could be placed at the base of the antenna if it is small compared to the quarter wavelength.

Neither the top nor the middle would be wise.


Posted  11/12/2012

Innovative Power Products Couplers
ConductRF Phased Matched RF Cables - RF Cafe
Lotus Communication Systems Modular RF Component Building Blocks - RF Cafe
Innovative Power Products Passive RF Products - RF Cafe
KR Electronics (RF Filters) - RF Cafe

Please Support RF Cafe by purchasing my  ridiculously low−priced products, all of which I created.

These Are Available for Free

 

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024

Webmaster:

    Kirt Blattenberger,

    BSEE - KB3UON

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website:

AirplanesAndRockets.com