After the successful completion of the XAA project in 2009. MIRAD has been requested again by EADS Asrteium (now Airbus Defence & Space) for the procurement of a X-band Antenna Assemby for the Egyptsat program (XAAE). The general design is based on the XAA unit, but the horn requires much higher gain values by weight and size limitations. The XAAE antenna consists of a corrugated horn, an unit for the generation of two orthogonal, circular polarizations and two coax interfaces. The antenna assembly configuration converts RF signals from the multiplexer into independent dual polarized signals pointing with high gain and precise positioning to the earth.
The task was to develop the antenna subsystem as an independent, stand-alone hardware to be integrate it into the corresponding pointing mechanism. The XAAE Antenna forms part of the Egyptsat-2 X- Band Antenna Assembly which comprises two (redundant) 2-axis pointing mechanisms, the XAAE Antenna and the Antenna Pointing Driver developed by Airbus DS. The satellite provided the Egyptian government with high-resolution views of the Earth for environmental, scientific and military applications. The data was transmitted to ground stations near Cairo and Aswan via an X-band communications terminal at a speed of 300-600 Mbit/s.
The figures illustrate the assembled horn (left), XAAE during antenna meaurements in MIRADs anechoic chamber (right)
After the successfull design and testing of the 2 units, they had been delivered to MIRADs customer and interagted into the spacecraft in 2012. In 2016 our customer comissioned MIRAD microwave to deliver another 2 units of an adatped version of the XAAE, the X-Band Antenna Pointing Assembly (XAPA), for Egyptsat-A launched in Februrary 2019.
Key technical challenges:
- On-board application
- Very lightweight design with 2.84 kg (spec.: <4.0 kg)
- Overall length < 700 mm in terms of mass and envelope
- Precise and controlled manufacturing
- Generation of high purity polarized signals
- X-band signal transmission (Tx: 8.025 – 8.400 GHz)
- Dual circular polarisation
- Antenna gain >22 dBi for ±4.25 deg
- Axial Ratio <0.2 dB (spec.: <0.77 dB)
- High isolation between polarizations >31 dB
- ECSS threshold margin >22 dB (Multipaction)