How to test a directional couplers? - RF Cafe Forums

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rakesh_aarya

Post subject: How to test a directional couplers?

Posted: Tue Jun 16, 2009 12:39 pm

Lieutenant

Joined: Tue Jun 16, 2009 12:25 pm
Posts: 4

Can anybody tell me how to test a directional coupler using vector network analyser...
I dont have specifications for the the directional coupler...the components are pretty old ....I need to get the specification using Vector network analyser...

thanks

cheers
Rakesh

nubbage

Post subject: Re: How to test a directional couplers?

Posted: Wed Jun 17, 2009 3:04 am

General

Joined: Fri Feb 17, 2006 12:07 pm
Posts: 268
Location: London UK

Hi Rakesh
The approach to testing depends on the configuration of the DUT:
is it coaxial or waveguide or stripline?
is the isolated port internally terminated?
or is there an external load with access to the isolated port?

_________________
At bottom, life is all about
Sucking in and blowing out.

rakesh_aarya

Post subject: Re: How to test a directional couplers?

Posted: Tue Jun 23, 2009 11:52 am

Lieutenant

Joined: Tue Jun 16, 2009 12:25 pm
Posts: 4

The problem is that the directional couplers that i have is from manufacture named ANZAC electronics. it was closed in 1960's.I dont have any datasheets for it... I need to find all the characteristics including the frequency range,etc..
I have a two port VNA by agilent technologies ...
can u tell for both kind of Dc.. The islolated port is terminated internally...

thanks
rakesh

nubbage

Post subject: Re: How to test a directional couplers?

Posted: Wed Jun 24, 2009 2:48 am

General

Joined: Fri Feb 17, 2006 12:07 pm
Posts: 268
Location: London UK

Hi Rakesh
I see Kirt has given you a very comprehensive answer under "components".
Not much to add to that. I guess the coupler of 1960s vintage has N type connectors, which at that time maxed out at 6 or 7GHz, so that probably sets a top limit to the frequency range. Above 7GHz the N-type connector starts to launch waveguide modes and the Reflexion Coefficient vs frequency becomes erratic (although today technology has improved that to around 12GHz).
The only point to be careful about then is obtain a good quality APC-7 to N type transition for at least 2 of the 3 exposed ports of the coupler.
Good luck with that.

_________________
At bottom, life is all about
Sucking in and blowing out.

Posted 11/12/2012

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