Constraints for antennas selection » History » Version 2

GAY, Adrien, 03/24/2015 01:52 AM

1 1 AUGER, Anne sophie
h1. Constraints for antennas selection
2 1 AUGER, Anne sophie
3 1 AUGER, Anne sophie
  
4 1 AUGER, Anne sophie
The type of antenna and associated performances are strongly linked to the considered central frequency. However, constraints are not the same for the aircraft antenna or for the ISAE antenna as we will describe below. 
5 1 AUGER, Anne sophie
6 1 AUGER, Anne sophie
h3. ISAE antenna:
7 1 AUGER, Anne sophie
8 1 AUGER, Anne sophie
Given the distance and the bit rate required to fulfil the specifications, a tracking antenna might be needed on the roof on the antenna. Nevertheless, as this solution is considerably increasing the system complexity, we will try to design a system with a fixed mounted antenna if possible.
9 1 AUGER, Anne sophie
10 2 GAY, Adrien
In fact, the need (or not) for tracking will be determined by the required figure of merit (G/T) of the antenna (cf part _"compution of (G/T)"_). As increasing the gain of the antenna will decrease its coverage ( $\theta_{3dB}$ ), if the required gain of the antenna leads to a coverage smaller than the aircraft action zone, a tracking antenna will be required. 
11 1 AUGER, Anne sophie
12 1 AUGER, Anne sophie
13 1 AUGER, Anne sophie
h3. Aircraft antenna:
14 1 AUGER, Anne sophie
15 2 GAY, Adrien
The connection between the aircraft and the ISAE building shall remain available for an inclination of 45° and an attitude of 15° at a distance of at least 50 km. However, a tracking antennas is not an option for the aircraft because of its possible fast angular motion and the integration complexity.
16 1 AUGER, Anne sophie
17 2 GAY, Adrien
These availability requirements impose huge constraints on the radiation pattern of the aircraft antenna. In fact,