Rudy M. Emrick

Implementation and Experimental Verification of Hybrid Smart-Antenna Beamforming Algorithm

In the literature (Zhang et al., and Rezk et al.), a hybrid beamforming algorithm utilizing a subset of array elements according to receive signal strength is proposed. The algorithm utilizes a smart switch which selects a subset of antennas that receive the signals with higher strength and a beamforming algorithm is performed to calculate the weights for the selected antennas. Since earlier results were based on simulations by Zhang et al., and Rezk et al., in this letter we present experimental results of testing a smart-antenna prototype with an eight-element array. This array is designed and implemented by the authors to verify the accuracy and performance of the proposed hybrid-beamforming algorithm. In general, the experimental results confirmed the simulation data. Specifically, it is shown that the proposed hybrid algorithm using a subset of the array has nearly the same performance as the adaptive system with the full array. Tradeoffs regarding beamwidth and the sidelobe levels are confirmed and additional experimental results illustrating the angle resolution of the developed system are presented

Implementation and Experimental Verification of a Smart Antenna System Operating at 60 GHz Band

With the introduction of the unlicensed spectrum at the 60 GHz range, the development of communication systems with data rates in Gb/s range has become feasible. However, there are quite significant challenges at this frequency range such as high propagation loss, oxygen absorption, antenna alignment and unavailability of high-gain, high power circuit elements. In this paper we present a novel 2-channel hybrid smart-antenna system operating at 60 GHz band which can be used with an antenna switching system to improve the signal power performance and to serve as an automated alignment system. The critical system parameters for a smart-antenna system at this frequency are the transmitter to receiver distance, element spacing, and antenna beamwidth. As the widely known beamforming assumptions may not hold for some configurations, a more general beamforming formulation is given in the paper to serve as a guideline for system designers. The twist angle of array elements is introduced as a new array design parameter. By selecting the optimal twist angle to help overlap radiation patterns, the fine alignment of the transmit and receive beams is established electronically using beamforming, thus reducing the cost of deployment and maintenance of the 60 GHz indoor communication systems.

New phase shifters and phased antenna array designs based on ferroelectric materials and CTS technologies

As the search continues for low-cost and high-performance components for the front-end devices for wireless communications systems, the focus has been on the use of MEMS technology; but some attention has recently been given to exploring new and innovative designs based on the Ferroelectric and the Continuous Transverse Stubs (CTS) technologies. In this paper we present new phase shifter designs and an integrated phased array antenna system based on the use of multilayer ferroelectric materials. Simulation results show that with the appropriate selection of the materials properties and the dimensions of the multilayer dielectric system, insertion losses may be reduced by as much as a factor of 100. These results also show that while only a slight reduction (15%) in the maximum achievable tunability was observed, it was possible to achieve significant improvement in the impedance matching characteristics. A procedure to enhance the radiation efficiency from an integrated ferroelectric/CTS phased antenna array design will be described and specific array designs discussed.

Monolithic 6W Ka-band high power amplifier

The design and performance of a fully monolithic 6W Ka-band power amplifier is outlined. Excellent agreement between modeled and measured performance was demonstrated. This 3-stage power amplifier, which power combines 16 FETs on the third stage, is fully matched on chip to 50/spl Omega/ at the input and output wire bond pads. Performance achieved /spl sim/20.5 dB gain from 24-32 GHz with a peak power of >6W and PAE of /spl sim/21%. This performance was achieved using a 0.1 /spl mu/m power PHEMT process. To the authors knowledge, this is the highest output power demonstrated from a single device in this frequency band.

Emerging Commercial Applications Using the 60 GHz Unlicensed Band: Opportunities and Challenges

The 60 GHz band has emerged as an international spectrum opportunity for short-range wireless communication networks. In this paper, opportunities that may leverage 60 GHz and the technology trends that will impact the commercial deployment of systems utilizing the 60 GHz frequency band are discussed. Millimeter-wave frequency bands have historically been costly to utilize and traditionally used almost exclusively for government and non-consumer products. Recent and ongoing advances in semiconductor technology and low cost high frequency packaging can be leveraged for low cost solutions that enable widespread deployment. An example of such a system operating in the millimeter-wave spectrum where bandwidths of ~3 GHz have been achieved. Multi-gigabit data transmission and reception over significant distances has also been realized to demonstrate the potential throughput of such a broadband wireless system.

Technology for emerging commercial applications at millimeter-wave frequencies

The 60 GHz band has emerged as an international spectrum opportunity for short-range wireless communication networks. In this paper, technology trends that can impact the commercial deployment of systems utilizing millimeterwave frequency bands is discussed. Millimeter-wave frequency bands have historically been costly to utilize and traditionally used almost exclusively for government and non-consumer products. Recent and ongoing advances in semiconductor and low cost high frequency packaging can be leveraged for low cost solutions that enable widespread deployment. In order to demonstrate the potential throughput of a broadband wireless system utilizing millimeter-wave spectrum, Motorola Labs has demonstrated multi-gigabit data transmission and reception over significant distances.

Automated Removal of Metallic Carbon Nanotubes in a Nanotube Ensemble by Electrical Breakdown

We present an automated electrical burning process to selectively eliminate conducting paths due to metallic and high-leakage ambipolar single-walled carbon nanotubes in aligned and randomly networked configurations of varying dimensions. Our algorithm is hysterisis immune and adjusts gate bias in between successive burn pulses to facilitate optimized electrical burning results. In back-gated devices, we show improvements in on/off ratio better than three orders of magnitude while achieving on-state current reduction of less than 25%. We also discuss important considerations that must be taken into account for obtaining good electrical burning results in top-gated devices.

Opportunities and Challenges in Utilizing Millimeter-Wave Spectrum for High Speed Wireless Communications

The 60 GHz band has emerged as an international spectrum opportunity for short-range wireless communication networks. In this paper, technology trends that can impact the commercial deployment of systems utilizing millimeter-wave frequency bands are discussed. Millimeter-wave frequency bands have historically been costly to utilize and traditionally used almost exclusively for government and non-consumer products. Recent and ongoing advances in semiconductor technology and low cost high frequency packaging can be leveraged for low cost solutions that enable widespread deployment. An example of such a system operating in the millimeter-wave spectrum where bandwidths of >3 GHz have been achieved. Multi-gigabit data transmission and reception over significant distances has also been realized to demonstrate the potential throughput of such a broadband wireless system.

On chip spatial power combining for short range millimeter-wave systems

Using spectrum around 60 GHz for high speed short range wireless systems has led to examination of antennas on chip. System analysis indicates that spatial power combining on chip may allow for a good combination of small size and compatibility with silicon amplifier performance indicates this approach may be the solution of choice. We have shown good agreement between modeled and measured performance for a candidate antenna element with three candidate elements shown which can achieve good gain in the frequency band of operation. Further, we have shown that system performance can be achieved in the very compact area of 7 x 7 mm2 while using a reasonable upper limit on output power from a silicon amplifier in this band.

Antenna Requirements for Short Range High Speed Wireless Systems Operating at Millimeter-Wave Frequencies

Large amounts of worldwide unlicensed spectrum at 60 GHz may provide solutions for future short range very high speed wireless solutions. A number of challenges remain for this spectrum to be a viable solution for high volume consumer applications. In this paper, we look closely at requirements for antennas in indoor scattering environments with a focus on signal to noise ratio for fading multi-path channels. These requirements are compared with realistic received signal to noise ratios that can be expected with Si based RF front ends. This analysis shows that high gain adaptive antennas will be required to achieve acceptable performance. Though antennas do scale with frequency we show that they are still too large for easy integration into consumer electronics