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AbstractÀModern active electronically steered antennas (AESA) operate in different platforms and systems. Inside EADS/ CASSIDIAN, the focus on X-band antennas today is on airborne and fighter nose radars, in satellite based SAR antennas (synthetic aperture radar) for earth observation, and ground surveillance and security radars.Active antennas are assembled with hundreds or even thousands of transmit/receive modules. This paper will describe an example of a so-called standardized module solution based on LTCC package technology. State-of-the-art modules are assembled with active components such as MMICs realized in GaAs technology, for example, the low noise amplifier (LNA) and the high power amplifier (HPA), silicon based devices, and passives. Assembly technologies are optimized for high yield series production inside CASSIDIAN MicroWave Factory. New semiconductor technologies, such as GaN (gallium nitride) are enablers for a new transmit/receive module generation. GaN/SiC based MMICs with higher power density compared with GaAs-based devices are technological challenges for innovative thermal management solutions and assembly alternatives. GaN power devices are soldered on modern heat sink materials with high thermal conductivity and matched CTE (between the MMIC and the heat sink).The results of thermal simulations comparing different heat sink materials in combination with soldering techniques will be discussed and an optimized solution will be shown. Another type of transmit/receive module technology based on RF-PCB and packaged MMICs will be discussed. Future applications of ground-based security radars, active antenna products with a one-dimensional array, and the need for cost-effective solutions seem to be a good fit for SMD-based products. Different packages, for example, QFN (quad flat pack no lead) and ceramic based (HTCC), mainly for power devices will be shown and compared.

Inthis contribution, the well-known vertically installed planar coupler is introduced briefly,and an improved assembly technique is proposed increasing the mechanical stability of the coupler.Then, the design of anovel multilayer planar,ultra-wideband, five-sectional 3dBdirectional couplerwith an easier fabrication process and lower heightispresented. In this approach, the necessary tight coupling at the center section for the desired ultra-broadband behavior is achieved with amultilayer configuration insteadofa vertically installed substrate. The manufactured multilayer couplerhas acoupling and insertionloss of 3.4 dB AE 1.1 dB and an isolation and return loss of better than 14 dB in the operating bandwidth between 3.1 -10.6 GHz. The designprocedure, identical for both coupler types, needs no time-consuming full-wave analysis and will be describedindetail for the novel multilayer coupler.

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