Depending on frequency, achieving the necessary phase matching surely must be
achievable electrically or, at microwave frequencies, via a variable length
waveguide?
I can't imagine that for a precision application one would rely on a coaxial
cable maintaining it's length and its other properties.
Jeff
Jeffrey K. Okamitsu, PhD, MBA
+1-609-638-5402
--- On Fri, 10/3/08, Bruce Griffiths <[EMAIL PROTECTED]> wrote:
From: Bruce Griffiths <[EMAIL PROTECTED]>
Subject: Re: [time-nuts] AC Connector On HP 5061B
To: "Discussion of precise time and frequency measurement" <[email protected]>
Date: Friday, October 3, 2008, 6:57 PM
Lux, James P wrote:
>
>> -----Original Message-----
>> From: [EMAIL PROTECTED]
>> [mailto:[EMAIL PROTECTED] On Behalf Of Jeffrey Okamitsu
>> Sent: Friday, October 03, 2008 2:46 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] AC Connector On HP 5061B
>>
>> For an interferometric application, isn't it sufficient to
>> maintain constant phase difference?
>>
>> Jeff
>>
>> Jeffrey K. Okamitsu, PhD, MBA
>> +1-609-638-5402
>>
>>
>>> Your absolutely right. The only two places that I can
>>>
>> think of, off
>>
>>> hand, would be televison and RADAR (systems with multiple
>>>
>> terminals).
>>
>>> Bill....WB6BNQ
>>>
>>>
>>>
>> Interferometers are another.
>>
>>
>
>
> Jeff is right, BUT, keeping constant phase difference without equal length
cables can be challenging. Consider a system I worked on which used phase
difference between 7 GHz signals received between two antennas about a meter
apart to steer a return beam at 32GHz back the same direction. And, it has to do
this while subject to temperature variations from -40 to +80C.
>
>
>
> James Lux, P.E.
> Task Manager, SOMD Software Defined Radios
> Flight Communications Systems Section
> Jet Propulsion Laboratory
> 4800 Oak Grove Drive, Mail Stop 161-213
> Pasadena, CA, 91109
> +1(818)354-2075 phone
> +1(818)393-6875 fax
>
>
> _______________________________________________
>
However for RF interferometers/bridges the phase differences have to be
accurately set, a constant phase difference isnt sufficient.
Bruce
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