Re: Implement Beamforming at 2.6 GHz

"Bevan Weiss" <kaizen__@NOSPAM.hotmail.com> wrote in message 
news:NAtnf.7796$vH5.389817@news.xtra.co.nz...
> clam wrote:
>> I am trying to implement a multiple antenna (16 channels) beamforming
>> system with 2.6GHz carrier freq.  To capture the phase difference between
>> channels, I need to downconvert the 2.6GHz RF to complex baseband using
>> some I/Q mixers.  I found out (from Marki) that a 2.6GHz I/Q mixer costs
>> over $150, which is way above my budget limit... I wonder if there is any
>> trick to avoid having mulitple mixers for such case?
>>
>> CJLam
>
> You need multiple baseband signals, as passband is simply too high speed 
> to deal with in any simple manner.
> This means you must have however many mixers as you require baseband 
> signals, and each LO must be the same (or at least have some very well 
> defined phase offset from each other such that you can compensate for it 
> in the baseband processing).
> You can surely find mixers for 2.4GHz cheaper than $150, is there anything 
> special about the mixer you need?

Or you could do the beamforming in r.f.  then you just need a bunch of 
spliiters, phase shifters, (variable gain amps or attenuators maybe) and 
combiners and only downconvert the beam outputs you need.

2.6 GHz isn't terribly critical for microstrip tolerances - why not build 
your own?

Best of luck - Mike