Lou &
Stan:
Thank you for your
inputs on this antenna matter.
On 70cm, have you
looked at a "stacked" patch arrangement with a director to give more gain? Stan
has previously talked of such an arrangement and it was proposed for the small
Eagle design.
On 2m, how high off
of the ground plane are you proposing for the dipoles?
In answer to Jim's
question of the symmetry of the arrays w.r.t the spin axis, I view that as a
non-problem for the RF patterns and operation.
Dick Jansson
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Here is a proposal for arranging the Eagle antennas
that Stan Wood and I worked out today.
By moving the 2M dipoles to the corners we have sufficient room for full
sized elements over the ground plane. The 2M antennas should get about
8dB.
Three L band patches in cavities should give us greater than 12 dB
gain.
By putting the S1,S2 and C band patches in hex shaped cups we maximize the
available space. The cup arrays can be NC machined out of a solid blank and
therefore attain precise control of the spacing. It may also serve as heat a
radiating device. Each patch will be circular polarized and fed with a single
feed from it's matching amplifier.
The 70 CM Circular polarized patch should have around 6 dB gain. We
will look at getting more gain on 70 cm. Seven S1 patches will be
mounted on top the 70CM patch. They should get about 15dB gain.
Tom's S2 interferometric patches are included.
Omni antennas similar to that used on P3D will be required on the opposite
side of the spacecraft.
There should also be room for the Sun Sensors on both sides of the
spacecraft.