What's wrong with this idea?

Thanks for your insightful comments. They've helped.

>
> > from the SPS a few time zones away will be coming in at an acute
> > angle, and thus not be as concentrated. And this might also cause
> > havoc with issues like restricted airspace.
>
> Airspace is not so much of a problem as the antenna geometry.
The further
> away from vertical, the larger and more elliptical the rectenna
must be, and
> the greater the atmospheric attenuation. At the 2.4 GHz band I am
not sure
> what the limit is, but at altitudes above about 50 degrees the
rectenna will
> start to beocme rather large and difficult to site.

If air travel though microwaves poses a concern for regulators,
IF . . then civil avaiation authorities might decide to restrict air
traffic through the airspace in which the power would be coming
through. When the SPS is directly overhead, the airspace restriction
might cover a column 10 miles in diameter. Now if we're beaming from
a SPS 10 to 40 degrees longitude away, then the beam to the rectenna
is no longer coming in vertically. It is cutting a swath across a
large area of land, with the beam occupying varying altitudes. If
the authorities don't have any issues with the safety, then never
mind about this concern :)

> > 3.) A transfer of microwave power to and from multiple orbiting
SPS
> > in order to take power where it is needed. This prevents
designing
> > SPS capacity for peak power load. Thus, a SPS orbiting above a
> > longitude in the night, can beam a portion of its power across
> > space, perhaps relayed by other SPSs, to a SPS above a daylight
> > longitude. This SPS would receive the microwaves, phase them into
>
> I do not see the value of relaying power from SPS to SPS. IT
complicates the
> system and reduces efficiency. Beaming power directly to Earth
rectennas is
> always the most efficient. Any single SPS can cover about 40% of
the
> Earth. You only need three SPSes to give 100% global coverage
with some
> overlap. Simply put the SPS'es where they are needed. They
can be off by
> 10 or 20 degrees lognitude with negligible performance hit.

I appreciate what you're writing, but let's step back a bit and
reconsider. I realize that for communications satellites, 3
satellites will give you coverage completely encircling the earth.
But as you yourself just wrote one will experience negligible
performance deterioration at 20 degrees offset from vertical, and I
can reasonably infer that the performance hit will increase as the
longitudinal separation increases, so considering that one may find
that the greatest peak-offpeak power demand discrepancy may be
offset by 180 degrees, then the question that follows is where is it
best to find that additional power.

Of course you state the obvious when you write that beamed power
from SPS to rectenna is the most efficient. What I'm asking about is
trying to maximize power received at the rectenna without building
too much capacity into the SPS. This can be achieved by power
sharing in orbit. And I grant you that we don't need to have a
linked chain of SPS relays, but we may need 1+ relays to cover 180
degrees separation between some SPSs. What I don't know is the
effect of the inverse square law on the direct transmission from one
SPS to another with 1 relay and its concomitant conversion loss.

Consider the following, radius of earth is 6,378.1 km, GEO is 35,786
km above earth surface, thus 2 SPSs with 1 relay, would entail two
legs for the transmission, each 59,629 km. This is compared to the
35,786 km from SPS to the rectenna.

Please check me on these calculations. If we designate power
received at rectenna from overhead SPS to be 100%, then power
received at the relay would be 36%. Is there further loss, in the
process of, not the distance involved of, redirecting the energy?
Now when the power is received at the destination SPS, it will be at
9%. But this is power coming from the dead of night across the
globe. Our time offset is 12 hours between the two SPSs. What is the
value of that power if there is no use for it at its designated
rectenna? I would contend it has no value. So beam it to another
rectenna whose market demands that power, even if we can only get 9%
of that power across that distance.

If we use just the line-of-sight scenario we are limited to, at
most, a 120 degree separation, with a direct line transmission of
73,030 km between the two SPSs. The received power would be 24% of
that received at the rectenna directly underneath the sending SPS.
Our time offset is 8 hours between the two SPSs. Now, we have more
power received at the final SPS, but it came from a market that is 8
hours offset from us. The question arises, does that sending market
have as much excess power to send as the one that is offset 12
hours? I don't know.

With sufficient SPS resources in orbit, the question becomes do they
trade power from nighttime SPS to daytime with help of a relay, or
do they trade only in line of sight, even though the power demands
of the rectenna markets may not be offset as widely as the day-night
scenario?

I feel that the question is not so easy to dismiss and that our
future SPS power engineers will optimize the solution based on facts
we don't have available to us. Thus, relays may be needed to
transmit the excess power from SPSs. I have trouble, barring
technological limitations, in seeing SPSs not utilizing their 24
hour sunlight cycles to maximum benefit by sharing power.

> >
> > its own transmission and beam them down to the rectenna. What
effect
> > would the microwaves have on the communication satellites KU band
> > signals? Such a lateral transfer of microwaves would cut a swath
> > through all of the uplink-downlink paths.
> >

>
> The biggest problem is that the best frequencies for SPS have now
been
> allocated to cell phone services.

Well, ain't that a bummer :(