I looked at the antenna proposal again this morning and we don't need to shoot for maximum gain on all antennas.
 
We don't need much gain for the U uplink so 1 patch is sufficient. A wide beamwidth (120 degrees) is more important. I assumed a 5 dBic antenna when designing the receiver. Likewise, too much gain on the V dowlink antenna may cause problems in acheiving availabilty over 70% of the orbit.
 
The proposed antennas include a 7-element patch array for S1. This could be cut to 3 elements (12 dBic) and still provide gain similar to the AO-13 S1 antenna. Less gain means lower sensitivity to squint.
 
73,
 
John
KD6OZH
 
----- Original Message -----
From: Louis McFadin
To: AMSAT Eagle
Sent: Wednesday, September 27, 2006 00:33 UTC
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.







Lou McFadin
W5DID
[email protected]


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.







Lou McFadin
W5DID
[email protected]


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