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 --------------------------- mailto:rjansson@cfl.rr.com rjansson@cfl.rr.com --------------------------- -----Original Message----- From: eagle-bounces@amsat.org [mailto:eagle-bounces@amsat.org] On Behalf Of Louis McFadin Sent: Wednesday, 27 September, 2006 0033 To: AMSAT Eagle Subject: [eagle] Proposed Eagle Antenna Arrays
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.