Ajay Gummalla

Small Antennas Based on CRLH Structures: Concept, Design, and Applications

Recent growth in the use of wireless wide-area networks (WWAN), the adoption of broadband wireless local-area networks (WLAN), and consumer demand for seamless global access has pushed the wireless industry to support most broadband wireless standards. These are supported in different geographical areas by supporting multi-band and multimode operation in cellular handsets, access points, laptops, and client cards. This has created a great challenge for engineers. It has pushed RF and antenna design beyond the capabilities of current technologies, opening the door for creative solutions that are 1) multi-band, 2) low profile, 3) small, 4) better performing (including MIMO), 5) accelerate time to market, 6) low cost, and 7) easy to integrate in the devices listed above. Conventional state-of-the-art antenna technologies satisfy a subset of these seven criteria; however, they hardly satisfy all of them. In this paper, we apply composite right-left-hand “CRLH-based” RF design to print penta-band handset antennas directly on the printed circuit board (PCS), and balanced-antennas for Wi-Fi access points. Full active and passive performance is presented, while describing key benefits of metamaterial antennas. We also analyze in detail how these antennas operate, while focusing on the main left-handed (LH) mode that enables antenna size reduction, and the ability to print them directly on the printed circuit board.

Compact metamaterial high isolation MIMO antenna subsystem

The compact MIMO antenna subsystem is proposed in this paper by integrating the metamaterial antenna array and the metamaterial directional coupler. The coupling between the two closely coupled antenna elements can be significantly reduced, thus boosting the radiation efficiency. The low far-field envelope correlation will help providing independent channel in the MIMO application. These results demonstrate a great potential of using the proposed MIMO antenna subsystem to increase the system performance.

Compact metamaterial antenna array for long term evolution (LTE) handset application

In the digital world, Moores Law states the number of transistors on Integrated Circuits (ICs) has been doubling every two years since 1965. While these ICs occupy only 10% of the wireless communication device area, the remaining 90%, referred to as RF Front-End Model (FEM), consists of a collection of discrete passive and active components such as antennas, filters, diplexer, duplexers, couplers, power combiner/splitter, and power amplifiers. While these powerful ICs enable effective implementation of Multiple Input Multiple Output (MIMO) digital processing, the main issue of MIMO RF FEM implementation in small devices such as handsets still remains unsolved. Without such a full solution, network providers cannot deploy next generation wireless broadband networks, such as 3GPP Long Term Evolution (LTE) networks, that can sustain tens of Mbps throughput with mobility. This paper addresses this specific problem by presenting an LTE MIMO air interface solution for handsets using metamaterial designs, which offer small, low-cost, and low-profile antennas printed directly on PCB for easy integration and simple manufacturing - all critical factors for rapid deployment and commercial success. The proposed metamaterial MIMO array consists of dual resonance antennas occupying λ0/10 × λ0/41 × λ0/387 volume at center frequency 771MHz of the LTE band 746–796MHz. The performances of two antenna array configurations with spacing of λ0/13 and λ0/5 are studied while quantifying its near-filed and far-field channel correlation.

Compact metamaterial quad-band antenna for mobile application

In this paper, we presented two examples of compact quad-band antennas which are designed based on MTM technologytrade. These multi-band antennas not only occupy smaller volume than conventional antennas such as monopole and PIFA, but also provide equal or better performances. In addition, these Metmataterial antennas are easily printed on the product PCB board, thus significantly reducing the cost in the mass production. The antenna performances clearly demonstrate that the proposed antennas can satisfy the needs of the modern mobile device applications.

Compact dual-band planar metamaterial antenna arrays for wireless LAN

The paper presents two examples of compact antenna arrays for MIMO applications which were designed based on MTM technologytrade. These multi-band antenna arrays occupy smaller volume than the conventional antennas while they provide equal or better performances. These antennas in addition to the excellent performance can be easily integrated with any PCB based circuit, thus significantly reducing the cost in the mass production. The compact antenna arrays can enable advanced MIMO solutions like switched arrays and beamforming arrays which can provide diversity gains in addition to MIMO gain.

Compact single and dual band zero-degree metamaterial N-way radial power combiner/divider

This paper introduces different types of N-way metamaterial radial power combiners/dividers. The metamaterial properties permit significant size reduction over a conventional N-way radial power combiner/divider. Metamaterial “MTM Technologies™” allow designing transmission lines with an electrical length of zero degree. The first design presented in this paper uses a 0° MTM line that reduces the size to one third of the conventional N-way radial divider. This size reduction improves overall performance by injecting fewer losses into the system and increasing the bandwidth of the radial power combiner/divider. Dual-band properties of Metamaterial are exploited in a second approach to design a dual-band MTM N-way power combiner/divider. In this second case MTM lines have a zero degree phase at a chosen frequency and 180° phase at a second chosen frequency which is not a multiple of the first one. This dual-band radial power combiner/divider is smaller than a conventional 180° single band radial power combiner/divider. Simulation and measurement data is presented in this paper for these different devices.

Compact dualband antenna subsystem for MIMO application

This paper presents a dualband MIMO antenna subsystem which employs two dualband metamaterial antenna elements and a directional coupler. The strong coupling between adjacent antennas due to their close proximity is reduced to achieve the full potential of using MIMO antenna array. The measured isolation is less than −13dB and radiation efficiency is more than 50% at both bands. The far-field envelope correlation is also studied in this paper.

Beyond 3G: Metamaterials application to the air interface

We have presented the first metamaterial MIMO antenna array implemented in a commercially available 802.1 In wireless LAN access point. Despite the extremely small size of the metamaterial array, its performance equals that of the much larger conventional antenna solution. The metamaterial antenna array utilized existing PCB fabrication technology and was readily integrated into the access point.

A novel broadband power amplifier architecture for high efficiency and high linearity applications

A novel and simple architecture for improving efficiency, bandwidth and linearity at backed-off RF power is presented. It is accomplished by a distributed amplifier with proper turn on and off of the transistor devices via an RF detector. Neither RF power combiner/splitter, DSP nor envelope amplifier is utilized. A MMIC prototype was designed and fabricated using a GaAs HBT process to verify this efficient, linear and broadband PA architecture and it measured 3% EVM and 24–25% PAE at 19.6dBm from 2.3GHz to 2.7GHz using a 54Mbps 64QAM OFDM modulation signal.