Harmonic measurements - RF Cafe Forums

The original RF Cafe Forums were shut down in late 2012 due to maintenance issues - primarily having to spend time purging garbage posts from the board. At some point I might start the RF Cafe Forums again if the phpBB software gets better at filtering spam.

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

-- Amateur Radio
-- Anecdotes, Gripes & Humor
-- Antennas
-- CAE, CAD, & Software
-- Circuits & Components
-- Employment & Interviews

-- Miscellany
-- Swap Shop
-- Systems
-- Test & Measurement
-- Webmaster

jabb

Post subject: Harmonic measurements

Posted: Tue Oct 03, 2006 11:26 pm

Captain

Joined: Tue Apr 18, 2006 10:40 pm
Posts: 11

hi...i've this spectrum analyzer that goes up to 26.5 GHz. my DUT runs at 18 GHz; if I want to check the second (36 GHz) or third harmonic (54 GHz) can that be done using the spectrum analyzer or because since it goes up to 26.5 GHz, it won't sense the signal at those harmonics?

is the only other thing possible is to use mixer to down convert?

RFTEJerry

Post subject:

Posted: Wed Oct 04, 2006 12:05 pm

Captain

Joined: Thu Apr 13, 2006 9:53 am
Posts: 17
Location: Florida

Hello jabb,

Your spectrum analyzer will not be able to measure your harmonics directly because they are out of the tuning range of the spec-ana. You will need to add an external down converter between your signal and the spec-ana. Many spec-anas can output their LO to external mixers to downconvert the signal to the range of the spec-ana and then compensate for the down conversion so you don't have to do the math.

I have down this with several HP (Agilent) spec-anas in my career. The reason the spec-anas LO is used to keep everything in "sync" with the internal sweep of the spec-ana.

Good luck,

RFTEjerry.

Posted 11/12/2012

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

My Daughter's Website: EquineKingdom