Roberto wrote: 
Thank you Jim.

John, if you would, please transmit your antenna concept drawing to the 
group.  I really like it.
Yes, please do this ASAP. I'm trying to get an Eagle Antenna Array paper ready for the San Fran meeting, & I'd like to have considered the latest possibilities.
 

. . . . S2/C is a technical win over S1/C because of the smaller antenna area on 
the spacecraft (18 dBi fixed design) and giving us the ability to 
separate the two antennas.  John and I discussed the spin doppler caused 
by the offset patches.  It will be insignificant.
I don't understand "spin Doppler" concerns. If the array elements are phased properly with a phase reference based on the spin (i.e. +Z) axis (regardless of whether the patches are symmetric or not), there is NO spin induced Doppler.


Jim wrote:

 
4.  Secondary Class 0 payload:  L/S1  -if and when the power budget and 
antenna pointing (fixed, nadir-pointing array) can support.  We recognize that it may not be usable 
in many areas due to elevated noise floor resulting from 802.xx devices, as discussed in San
Diego and documented in measurements and analysis.  
NO PERFORMANCE LEVEL IS TO BE PROMISED.
[SNIP] 
6.  Use of all secondary payloads will be subject to acceptable costs in power, heat, and/or mass,
as assessed by analysis or testing.  They are to be turned off if regulatory constraints are 
imposed post launch.  They will not be flown at all if shown to be not feasible through 
analysis or testing.
I agree that added receivers do little to increase complexity, but an added xmtr (plus its power conditioning, plus higher powered antenna relays, plus antennas capable of handling high power without generating RFI, plus more heat load, .. plus .. plus .. ) is a great increase in complexity. Our arguments on why S1 downlinks in the future, given the PRESENT level of RFI  and its rate of increase over the next 15 years, are a poor investment.

If we don't "promise" a performance level, then we must face the problem that Franklin pointed out with AO-40 -- a set of realistic user requirements was never presented, so everyone was just flying blind.

73, Tom