Mojgan Daneshmand

RF MEMS Satellite Switch Matrices

Microelectromechanical systems (MEMS) technology has the potential of replacing many of the radio frequency (RF) components used in to days satellite communication systems. In many cases, such RF MEMS components would not only substantially reduce size, weight, and power consumption, but also promise superior performance when compared to that of current technologies. The benefits of MEMS technology be come more pronounced for switch matrices because there is a large number of switching elements and, therefore, any size and mass reduction would have large overall impact. Though there has been some controversy on the reliability and lifetime of RF MEMS switches, significant improvements have been made and RF switches with billions of switching cycles have been demonstrated. This article describes the potential applications of RF MEMS switch matrices in the satellite industry, where mass reduction and performance improvement is crucial.

Scalable RF MEMS Switch Matrices: Methodology and Design

This paper proposes new solutions for implementing wideband large switch matrices. These solutions are based on crossbar and L-shaped topologies. This paper introduces a high-performance wideband switch cell to build up scalable NtimesN switch matrices and gives an account of the design, fabrication, and characteristics of the switch cell and a 3times3 crossbar switch matrix. The chosen design procedure is seen to be appropriate since it produces valid measured results. In addition, this paper presents an RF microelectromechanical systems L-shaped switch matrix, which indicates less variation of characteristics for certain types of connectivity. It also demonstrates that for a 4times4 switch matrix, there is a 50% improvement in insertion loss and phase-shift variation.

Thermally Actuated Latching RF MEMS Switch and Its Characteristics

Here, a new thermally actuated latching wideband RF microelectromechanical systems (MEMS) switch is presented. The switch employs two thermal actuators connected to two thin metal arms which serve as signal lines of coplanar waveguide switch. The actuators pull the thin arms sequentially, and latch the switch. The switch can be actuated on and off by using either short voltage or current pulses. Using a dielectric bridge (nitride) as an interface between the actuators and the thin arms, the RF circuitry is separated from DC actuators, allowing wide-band operation. The switch demonstrates an excellent wideband RF performance with an insertion loss of better than 0.3 dB up to 20 GHz and better than 0.8 dB up to 40 GHz. The return loss and isolation of the switch is better than 20 dB for the entire frequency band. The switch also has a very satisfactory repeatability with better than 0.1-dB variation in insertion loss and less than 1-dB variation in return loss and isolation at 30-dB level up to 6000 times switching cycles. The switch has been also successfully tested for RF power handling capability up to 40 dBm. The proposed switch has very simple RF structure which makes it an ideal candidate to be integrated in the form of more complex circuitry. An application of the proposed switch for a band selection network which is used in multiband transceivers has been presented here.

Monolithic RF MEMS Switch Matrix Integration

In this paper, for the first time, monolithic integration of an RF MEMS switch matrix is presented. Novel SP3T RF MEMS switches are designed and monolithically integrated with an electromagnetically coupled interconnect network. A thin film fabrication process exclusively for this purpose is developed and fine tuned. A prototype unit of a 3times3 monolithic switch matrix is fabricated and tested. The measured results show a good RF performance for the frequency range of 9.5GHz to 13.5GHz. The proposed monolithic 3times3 switch matrix can be easily expanded to larger matrices using Clos networks

RF MEMS waveguide switch

In this paper, a unique concept for RF MEMS waveguide switches is introduced. The proposed structure employs a ridge waveguide integrated with MEMS actuators. The switch combines the advantages of MEMS technology with the high power handling capability of waveguide technology. It also promises to be useful in high frequency applications 100-200 GHz. In order to demonstrate the concept, a Ku-band waveguide switch employing a thermally plastic deformable MEMS actuators has been fabricated and tested. The achievable measured results are very encouraging, demonstrating the potential of such novel type of MEMS switches.

Redundancy RF MEMS Multiport Switches and Switch Matrices

The objective of this paper is to investigate novel configurations of planar multiport radio-frequency (RF) microelectromechanical systems (MEMS) C-type and R-type switches and redundancy switch matrices for satellite communications. An in-house monolithic fabrication process dedicated to electrostatic multiport RF MEMS switches and switch matrices is developed and fine tuned. The proposed C-type switch is a four-port device with two operational states. This switch exhibits an insertion loss of less than 0.3 dB and isolation of about 25 dB at satellite C-band frequency range. The novel R-type switch is also a four-port device with an additional operational state. The measured results show an insertion loss of better than 0.4 dB and an isolation of better than 25 dB at C-band. This is the first time that an R-type RF MEMS switch is ever reported. Several of these switches are integrated in the form of redundancy switch matrices, and two novel monolithic five to seven redundancy switch matrices are developed, fabricated, and tested. It is shown that the additional operating state of the R-type switch not only decreases the number of elements by 50% but also reduces the size drastically

Microbead-assisted high resolution microwave planar ring resonator for organic-vapor sensing

A microbead-assisted planar microwave resonator for organic vapor sensing applications is presented. The core of this sensor is a planar microstrip split-ring resonator, integrated with an active feedback loop to enhance the initial quality factor from 200 to ∼1 M at an operational resonance frequency of 1.42 GHz. Two different types of microbeads, beaded activated carbon (BAC) and polymer based (V503) beads, are investigated in non-contact mode for use as gas adsorbents in the gas sensing device. 2-Butoxyethanol (BE) is used in various concentrations as the target gas, and the transmitted power (S21) of the two port resonator is measured. The two main microwave parameters of resonance frequency and quality factor are extracted from S21 since these parameters are less susceptible to environmental and instrumental noise than the amplitude. Measured results demonstrate a minimum resonance frequency shift of 10 kHz for a 35 ppm concentration of BE exposure to carbon beads and 160 kHz for the polymer based ad...

Integrated interconnect networks for RF switch matrix applications

In this paper, two new types of integrated RF interconnect networks are presented. The circuits are printed on double-sided alumina substrates, eliminating the need to use multilayer manufacturing technology. The interconnect networks employ finite ground coplanar lines and vertical transitions and can be easily integrated with semiconductor and microelectromechanical-systems switches. A wide-band 3/spl times/3 interconnect network utilizing single and double three-via vertical transitions is investigated theoretically and experimentally. The measured results show a return loss of -20dB and an isolation of better than -40dB up to 30 GHz. A vialess double-sided interconnect network is also studied and optimized for satellite Ku-band applications. This type of interconnect network uses a process requiring only front and back pattern metallization. The measured results indicate a return loss of better than -17dB and an isolation of better than -45dB.

Multiport MEMS-based waveguide and coaxial switches

In this paper, a new concept of three-dimensional (3-D) multiport RF microelectromechanical systems (MEMS) switches is introduced. The proposed structures are based on integrated MEMS actuators inside 3-D waveguide and coaxial structures. These switches are well suited for high-power redundancy switch matrices for satellite communication, as well as millimeter-wave applications. To demonstrate the concept, a C-type waveguide switch is fabricated and tested. The use of a unique bi-layer curled electrostatic actuators, results in a very good RF performance with an isolation of 36-40 dB and a return loss of -20dB over a 7% bandwidth at satellite Ku-band. This paper also presents for the first time a new type of MEMS-based coaxial switch, which can offer a much larger bandwidth with miniaturized dimensions. To prove the concept, prototype units of single-pole single-throw and C-type switches are designed, fabricated, and tested. The measured results demonstrate a bandwidth of 65% for the C-type MEMS-based coaxial switch.

Monolithic crossbar MEMS switch matrix

This paper presents a novel approach to implement RF MEMS large size switch matrices. The concept is based on the implementation of a crossbar switch matrix and the introduction of unique switch cells that can be easily used to expand the matrix size. A six-mask fabrication process is adapted to fabricate the proposed four-port switch cell as well as the switch matrix samples. The switch cell has two operational states: thru and turn. This allows the cell to be easily integrated in the form of a crossbar switch matrix. Novel series contact cantilever beams have been used to implement the entire structure. The measured results for the entire switch cell show excellent insertion loss of 0.5dB, return loss of better than −20dB and isolation of −25dB for the thru path. The turn state of the switch shows a good performance of 0.4dB insertion loss, −18dB return loss and better than −25dB isolation for the frequency band of interest. A 3×3 switch matrix is implemented that shows 98% size reduction in comparison with the previously reported RF MEMS switch matrices.