Volker Ziegler

RF-MEMS Switch and Phase Shifter Optimized for W-Band

This paper presents the optimization of the low-complexity RF-MEMS technology for W-Band, the fabricated switches and phase shifters. All devices are fabricated on a thinned silicon substrate using only one metallization. The basic W-Band switch used for the phase shifter is presented in detail showing a very wide band RF-behaviour with an almost constant insertion loss of about -0.3 dB from 50 - 100 GHz. The 3-bit phase shifter itself with the design frequency of 76.5 GHz is realized using one loaded-line and two switched-line phase shifter elements. The mean insertion loss of the whole phase shifter is -5.3 dB and the phase deviation was calculated to be 13.4deg. Furthermore an extension to a 4-bit phase shifter by the use of a dual-state microstrip line phase shifter element is given. In addition, a short switching-time of the switches of only 15 mus was measured.

Design and Analysis of a Reflectarray Using Slot Antenna Elements for Ka-band SatCom

This paper presents a folded reflectarray designed for Ka-band satellite communication applications. The array element is a dual-polarized slot antenna with multilayered PCB structure and is designed to operate at 29.5-30.8 GHz band for both transmitting and receiving with single linear polarization. Vias are employed to suppress the surface wave propagation and reduce the mutual coupling between adjacent array elements, for achieving a reflectarray with a wide scan angle range. An equivalent circuit model for the array element is developed and it agrees well with the EM simulation results. Several passive demonstrators consisting of 116 elements spaced by 0.5λ30GHz were fabricated and measured. The experimental results show that the presented reflectarray is capable of steering the beam up to ±60° in both Eand H-planes with low cross-polarization level.

Simplified RF-MEMS Switches Using Implanted Conductors and Thermal Oxide

This paper presents microwave capacitive RF-MEMS switches based on a novel simplified fabrication process. The devices are fabricated on a silicon substrate using only one metallisation layer. For the capacitive coupling of the switch, an implanted conductive region and thermally grown silicon oxide is used instead of a second metal layer and an additional dielectric layer. In addition, the formerly used bimorph metallisation layer is replaced by a single-metallisation concept, which results in an increased temperature range of operation. The simplified process as well as the switch topology used lead to high performance and highly reliable RF-MEMS switches. RF-measurement results are presented of Ku- and K-band series switches and a Ka-band parallel switch with low insertion losses between -0.2dB and -0.3dB and isolation of e.g. -17dB at 30GHz

Very low complexity RF-MEMS technology for wide range tunable microwave filters

This paper presents tunable microstrip filters in the GHz range, fabricated on silicon in a very low complexity RF-MEMS process with only one metallization layer. Affected by a mechanic stress gradient in the metallization, free standing parts of the structure roll up. These bended beams can be switched onto the substrate by electrostatic actuation and thus tune the resonance frequency by changing the /spl epsiv//sup r eff/ of the resonant structure. The technology offers the possibility to realize tunable filters with a small insertion loss of less than 1.5dB at 30GHz for bandpass and for bandstop filters and a large frequency shift of about 20% in operation frequency.

Hybrid Integrated RF-MEMS Phased Array Antenna at 10GHz

In this paper, a one-dimensional electrically steerable RF-MEMS phased array antenna for operation at 9.5 GHz is demonstrated. The antenna itself is a four by eight patch antenna array realised on low-loss Teflon substrate and the feed network made out of the same substrate is a one-to-four corporate feed network. The phase shifting necessary to steer the main beam of the antenna in the H-plane of the aperture is achieved by four 3 bit RF-MEMS phase shifters, which are integrated in a hybrid fashion between the antenna and the feed network. The paper describes the integration of the different elements in a standalone phased array antenna demonstrator. The design of the 3 bit RF-MEMS phase shifters is presented and validated by very good measurement results. Finally, the measured radiation characteristic of the complete phased array antenna is shown for different switching states of the phase shifters.

Imaging Millimeter Wave Radar with Phased Array Antenna

In the joint research project „RADARAUGE“, funded by the Federal Ministry of Education and Research (BMBF), the development of a phased array radar sensor operated at 79 GHz with active MEMS-based micro-switches is targeted for automotive environmental recognition purposes. Basically, driver assistance systems need a narrow beam to detect objects at long distances and to reject reflections originating from objects located next to the road. To survey the traffic on several lanes in medium and short distances, however, a wide detection range is required. The movement of vehicles in the neighbourhood shall be monitored to support lane change manoeuvres etc. Both tasks can be covered by a phased array antenna, which provides electronic beam steering of a narrow lobe over a wide detection range. Beside the automotive application, the sensor can be used to detect wake-vortices of departing and landing aircrafts. This allows the optimization of the time intervals typically inserted between take-off and landing procedures.

Design and experimental evaluation of compensated bondwire interconnects above 100 GHz

Different types of bondwire interconnect for differential chip-to-antenna and single-ended chip-to-chip interfaces are investigated. Two differential compensation structures for various lengths of ...

Broadband 57–64-GHz WLAN Communication System Integrated Into an Aircraft Cabin

This paper describes the specific development of a high-data-rate 57-64-GHz point-to-multipoint wireless local-area network communication system and the worldwide first installation of such a system into an aircraft cabin mock-up. All of the system components, from the RF-chip-set, the low-temperature cofired ceramic integrated antennas, and RF modules to the baseband processor, the medium access control, and the application software were purpose-designed for a wireless backbone for in-cabin communication. The integration aspects of these system components into a passenger aircraft cabin mock-up (ceiling and passenger seat-integration) as well as successful system performance tests were carried out and are reported here.

Low complexity RF-MEMS switch optimized for operation up to 120°C

This paper presents a RF-MEMS switch optimized for high temperature range of operation using a temperature stable metallization. The devices are fabricated on a silicon substrate in very low complexity process using only one metallization. The performed measurements characterize the properties of the metallization and also the properties of the entire switch in terms of creeping behaviour, RF performance and charging effects at different temperatures. A stable operation up to 120degC is demonstrated and the principle reliability of the switches is shown by 109 switching cycles.

Antenna array elements for Ka-band satellite communication on the move

Two dual-polarised reflectarray unit cells for the folded reflectarray and one linearly polarized array element for direct radiating array for Ka-band SatCom on the move are presented in this paper. All of these antenna unit cells have multi-layered structure and are designed for the smart array antenna with beams that can be steered to large scanning angles. The unit cells for reflectarray are designed to operate at 29.5-30.8GHz band for both transmitting and receiving while the antenna element for the direct radiating array is designed to have a dual band operation: 29.5-30.8GHz for transmitting and 19.7-21.0GHz for receiving. These three antenna elements have a low profile and the simulation results show that they exhibit good radiation performance over the required frequency bands.