1.2m Ku band VSAT antennas from Patriot

If you are learning to use the link budget calculator then you can use the technical antennas parameters below as real examples of the input variables. 

When considering the  uplink interference entry in the link budget you can try either the 35 or 26 dB values for the uplink cross polarisation interference. In both cases the same off-axis gain envelope applies, so you might have 7 interference entries on the uplink and 7 interference entries on the downlink as follows:

Satellite 6 deg to the left (work out the value using the off-axis gain envelope)
Satellite 3 deg to the left (work out the value using the off-axis gain envelope)
Cross polarisation interference from same satellite (use 35 or 26 dB, as above)
Beam reuse interference from same satellite (just guess, say 33 dB)
Satellite 3 deg to the right (work out the value using the off-axis gain envelope)
satellite 6 deg to the right (work out the value using the off-axis gain envelope)

In your opinion, what is the value in overall system terms of the extra cross-polarisation performance of the dual optics antenna ?   What capacity loss results from some dishes being mis-pointed to -1 dB on transmit and their cross polarisation emissions degraded to 26 dB ?
 

1.2m Ku band VSAT antenna - single optic

Cross polarisation: on-axis 35 dB, within 1 dB beam width 26 dB.

Transmit frequency: 13.75 -14.5 GHz    Receive frequency: 10.7 - 12.75 GHz

Noise temperature = 58K at 10 deg elevation, 53K at 30 deg elevation

Transmit gain=43.3 dBi     Receive gain=41.8 dBi

Off-axis side lobe performance (dBi):

29-25 log q     2.5°<q<7°
+8                 7°<q<9.2°
32-25 log q     9.2°<q<48°
-10                48° < q

Focal length = 76.2 cm, f/D=0.635, Offset angle=22 deg

1.2m Patriot Ku band VSAT antenna

1.2m Ku band VSAT antenna - Gregorian dual-optics

Meets Eutelsat's rule that the cross pol performance within the -1 dB transmit beam width is better than 35 dB.

Cross polarisation on axis 35 dB, within 1 dB beam width 35 dB.

Transmit frequency: 14.0 -14.5 GHz  Receive frequency: 10.7 - 12.75 GHz

Noise temperature = 58K at 10 deg elevation, 53K at 30 deg elevation

Transmit gain=43.3 dBi     Receive gain=41.8 dBi

Off-axis side lobe performance (dBi):

29-25 log q     2.5°<q<7°
+8                 7°<q<9.2°
32-25 log q     9.2°<q<48°
-10                48° < q

Focal length = 76.2 cm, f/D=0.635, Offset angle=22 deg

1.2m Patriot VSAT Ku band antenna Gregorian dual optics

Go to Patriot web site for full technical specification and details of many other antenna types and sizes

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► Page created 28 Sept 2004, amended 3 Jan 2005