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!

phase array: steering problem, help? - 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

Mr.Sánchez
 Post subject: phase array: steering problem, help?
Posted: Tue Dec 23, 2008 2:46 pm 
 
Lieutenant

Joined: Tue Dec 23, 2008 2:01 pm

Posts: 2

Location: Madrid

Hello,

I've been working on a 1x8 linear phase array. The antenna system is working perfect, but I came across with a problem when making the algorithms for steering.

Imagine your phase shifters give a maximum of 400º shift for a particular frequency. Now suppose the required shifts for the eight elements are for example: 0 90 180 270 360 450 540 630º.

I programmed an algorithm that used the periodicity of the signal so those shifts are the same as: 0 90 180 270 360 90 180 270. I moduled all phase shifts to 360.

When testing the radiation pattern in a anechoic chamber, the result was disturbing. I got a maximum in the desired direction but the whole pattern was very smooth, with less lobes that it should have, much less directivity.

Then we used another algorithm that worked. Our phase shifter are switched lines shifters, so in this new algorithm we worked with temporal retards instead of thinking of degrees. The thing is... it works.

Then my question is, why doesn't it work moduling the shifts to 360? shouldn't the pattern be the same??

I'll be thinking about it,

thanks a lot in advance

---

i'll see you guys around, i'm new in this world (1 year working after finishing college) and i love these forum where you can share information and knowledge.


 
   
 
maxwelltesla
 Post subject: Phase Shifter
Posted: Fri Jan 16, 2009 4:09 pm 
 
Lieutenant

Joined: Thu Jun 24, 2004 3:10 pm

Posts: 4

What frequency are you working? Type of phase shifter... MEMS?

 
   
 
Mr.Sánchez
 Post subject: phase array
Posted: Mon Jan 19, 2009 12:39 pm 
 
Lieutenant

Joined: Tue Dec 23, 2008 2:01 pm

Posts: 2

Location: Madrid

i'm working from 2 to 6 GHz, and with switched lines.

if you can help me, I'd be glad to explain to you my doubt in more detail, although I think it's more or less clear my problem.

Thanks


 
   
 
karthik
 Post subject: Re: phase array: steering problem, help?
Posted: Mon Jan 04, 2010 10:59 pm 
 
Colonel

Joined: Tue Apr 11, 2006 8:13 pm

Posts: 34

I dont know if you were able to solve your problem. If you did, could you please post your finding? If not, I have a couple of questions/suggestions:

1. Can you compare the time delay (which worked) to the phase (which did not work).

2. You can measure the phase that is actually being set - measure the phase from the antenna element to the output of the combiner - and ensure that the phase relationship between adjacent elements is what you expect.

From your description, it appears the phase (and/or amplitude) relationship between the elements is not what you had calculated.


 
   
 
fred47
 Post subject: Re: phase array: steering problem, help?
Posted: Sat Jan 23, 2010 12:08 am 
 
General
User avatar

Joined: Wed Feb 22, 2006 3:51 pm

Posts: 106

If the antenna elements were isolated from each other, the phase shifter and the time delay approaches would in fact give the same result.

But...

Antenna elements couple to each other, which changes the driving point impedance, and a transmission line further transforms the impedance.

Summary: Phase shifters can work, but you have to take inter-element coupling into account.

Good Luck!


 
   
 
biff44
 Post subject: Re: phase array: steering problem, help?
Posted: Sat Feb 06, 2010 10:23 am 
 
Colonel

Joined: Wed Apr 08, 2009 11:07 am

Posts: 34

This is a trivial point, and I hessitate to bring it up. But you do realize that a "switched line" phase shifter, set into any one position, will have a wildly different phase shift at each and every frequency over the 2 to 6 GHz band. For instance, if you dialed in 180 degrees at 2 ghz, if you touched nothing but simply swept the frequency to 4 GHz, you should get 360 degrees out of it (I am assuming you de-embedded the measurement to right at the switches in the switched line phase shifter, and that the switched lines were all less than a wavelength in length).

If you use software that recognizes the actual time delay switched in for each of the switched lines, then that software will take into account the frequency and calculate the true phase shift at that one frequency.

_________________

Rich

Maguffin Microwave Consulting

www.MaguffinMicrowave.com


 
   
 
biff44
 Post subject: Re: phase array: steering problem, help?
Posted: Sat Feb 06, 2010 10:33 am 
 
Colonel

Joined: Wed Apr 08, 2009 11:07 am

Posts: 34

The more I think about this, the more I wonder what the absolute phase shift is of each of your 8 phase shifters, vs setting and frequency. A phase shifter chip, for instance, might have tight specifications for the relative phase shift from one setting to another. But if you measured the absolute phase shift of chip #1, vs. chip #7 that might have been manufcatured 6 months later, I think all bets are off!

_________________

Rich

Maguffin Microwave Consulting

www.MaguffinMicrowave.com


Posted  11/12/2012

Berkeley Nucleonics Corporation - RF Cafe
Innovative Power Products Passive RF Products - RF Cafe
Innovative Power Products Passive RF Products - RF Cafe
PCB Directory (Manufacturers)
withwave microwave devices - 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