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!
Windfreak Technologies Frequency Synthesizers - RF Cafe

? gamma for a home-made 70cm 6-element yagi ? - 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

rf_2_go
 Post subject: ? gamma for a home-made 70cm 6-element yagi ?
Posted: Mon May 30, 2005 8:09 pm 
 
Lieutenant

Joined: Mon May 30, 2005 7:51 pm

Posts: 1

Location: colorado

hi, with a 35" wood stick and 6 pieces of 3/32 welding rod a 70 cm yagi was made. using the AD8302 eval bd to check the reflected energy the

peak Vg was for 429 MHZ. the open end of the DE was trimmed

at Fin=433.9 M until the same peak Vg was gotten. the new peak was

at F=433.4 this is close enough to 433.9. the gamma was calculated by

Vg=928 at no input signals to the 8302 and Vg=1447 mV at its peak.

gamma = (1447-928) / 30 = 17.3 (it's really a minus ). for a VSWR

somewhere between 1.22 and 1.43.

my question is for those of you who have too made your own yagi

and measured its gamma ... what did you get ?

and do you know what is a ball-park gamma for commercial yagis.

previous tests of gamma with the 8302 used a string of VAT's on one

input to make the Vg = 900 mV. but i was getting this funny compression with each add'l VAT dBm unit. until i figured the VAT's themself were

adding up a significant insertion loss compared to the add'l return loss

i was trying to achieve. anyway, now i simply utilize the beauty of this

8302 device by letting the A & B inputs be un-equal and using the Vg

output as the experimental data. then divide whatever it is by the slope of 30mV/dBm to get a number for ret loss. easy as pie this way

Posted  11/12/2012

Amplifier Solutions Corporation (ASC) - RF Cafe

withwave microwave devices - RF Cafe

Holzworth RF Synthesizers

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