Re: [amsat-bb] Re: HEO naïveté
ke9vee at gmail.com
Sat Feb 7 08:10:02 PST 2009
On Sat, Feb 7, 2009 at 10:50 AM, Gary Joe Mayfield
<gary_mayfield at hotmail.com> wrote:
> The microwave thing always gets me though. If the antennas are too big how
> come they can get them on cube sats? I know the correct statement is
> high-gain antennas are too big. The problem is gain antennas need some
> pointing mechanism (complicated and expensive) and they need to be pointed
> no matter what band they are designed for. When using omni antennas the
> lower frequency will yield higher performance due to lower path loss....
CubeSats buzz around 180 miles over your head. At apogee, AO-13 was
23,000 miles from the ground.
That's why the gain antennas were needed and when you add up the power
required for a transponder to handle lots of stations at the same
time, then the link budgets and antenna sizes (for more gain) at
higher frequencies begin to make a LOT more sense.
The tightrope the developers walked was always how to deliver
performance on frequencies that stubborn members demanded always be
used. The S-mode stuff held much promise with AO-40. James Miller,
G3RUH presented all the superior reasons for S-mode (the paper is
still in the archives) but for a large percentage of members it was
always "2 meters on the downlink or I will withhold funding".
Just like those who raise a stink now whenever almost anything is
proposed requiring more than a fifteen year old dual band handheld and
an Arrow antenna...
As has been hinted around this thread, our problems are almost 100%
self-inflicted. We have shot our toes off until we have none left to
shoot. I don't blame the leadership -- this "club" contains some of
the most stubborn individuals in all of hamdom. Perhaps if AMSAT can
stick around long enough, the naysayers will all eventually die off
and we can move forward with reality instead of dreamy-eyed
reminiscing about days gone by and what might have been.
More information about the AMSAT-BB