Reconfigurable Reflectarrays and Array Lenses for Dynamic Antenna Beam Control: A Review

Advances in reflectarrays and array lenses with electronic beam-forming capabilities are enabling a host of new possibilities for these high-performance, low-cost antenna architectures. This paper reviews enabling technologies and topologies of reconfigurable reflectarray and array lens designs, and surveys a range of experimental implementations and achievements that have been made in this area in recent years. The paper describes the fundamental design approaches employed in realizing reconfigurable designs, and explores advanced capabilities of these nascent architectures, such as multi-band operation, polarization manipulation, frequency agility, and amplification. Finally, the paper concludes by discussing future challenges and possibilities for these antennas.Comment: 16 pages, 12 figure

Tunable decoupling and matching concepts for compact mobile terminal antennas

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Low-Profile Fully-Printed Multifrequency Monopoles Loaded with Complementary Metamaterial Transmission Line

The design of a new class of multifrequency monopoles by loading a set of resonant-type complementary metamaterial transmission lines (CMTL) is firstly presented. Two types of CMTL elements are comprehensively explored: the former is the epsilon negative (ENG) one by loading complementary split ring resonators (CSRRs) with different configurations on the signal strip, whereas the latter is the double negative (DNG) one by incorporating the CSRRs and capacitive gaps. In both cases, the CMTLs are considered with different number of unit cells. By cautiously controlling the geometrical parameters of element structure, five antenna prototypes coving different communication standards (GSM, UMTS, DMB and WiMAX) are designed, fabricated and measured. Numerical and experimental results illustrate that the zeroth-order resonance frequencies of the ENG and DNG monopoles are in desirable consistency. Moreover, of all operating frequencies the antennas exhibit fairly good impedance matching performances better than -10dB and quasi-omnidirectional radiation patterns

Transparent and Flexible Radio Frequency (RF) Structures

With increasing demand for a wearable devices, medical devices, RFID, and small devices, there is a growing interest in the field of transparent and flexible electronics. In order to realize optically transparent and flexible microwave components, novel materials can be used. The combination of new materials and radio frequency (RF) structures can open interesting perspectives for the implementation of cost effective wireless communication system and wearable device design. The transparent and flexible RF structures can facilitate its application in the transparent and curved surfaces. In this dissertation, we present several demonstrations, all based on optically transparent and flexible materials and structures. We firstly demonstrate an optically transparent, flexible, polarization-independent, and broadband microwave absorber. The bow-tie shaped array which possesses double resonances is designed and measured. The combined resonances lead to more than 90% total absorption covering a wide frequency range from 5.8 to 12.2 GHz. Due to the use of thin metal and PDMS, the whole structure is optically transparent and flexible. Secondly, we demonstrate a new method for fabricating transparent and stretchable radiofrequency small antennas by using stretchable micromesh structures. Size reduction is achieved by using the zeroth-order resonant (ZOR) property. The antennas consist of a series of tortuous micromesh structures, which provides a high degree of freedom for stretching when encapsulated in elastomeric polymers and is optically transparent. Accordingly, these antennas can be stretched up to 40% in size without breaking. The resonant frequency of the antennas is linearly reconfigurable from 2.94 GHz to 2.46 GHz upon stretching. Next, we describe an ultra-low profile and flexible triple-polarization antenna. It is realized by using ZOR array antenna with high port-to-port isolation. This flexible antenna is fabricated with a flexible substrate and silver nanowire vias to be used in various wearable applications. Lastly, we demonstrate a dual-band tri-polarized antenna based on half-mode hexagonal (HMH) SIW structure. CRLH HMHSIW antenna and ZOR HMHSIW antenna are designed to have dual-band operating frequencies. This novel antenna can provide much improved wireless communication efficiency for the WBAN system under various incident field angles and polarizations.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/147562/1/tjang_1.pd

Wideband and UWB antennas for wireless applications. A comprehensive review

A comprehensive review concerning the geometry, the manufacturing technologies, the materials, and the numerical techniques, adopted for the analysis and design of wideband and ultrawideband (UWB) antennas for wireless applications, is presented. Planar, printed, dielectric, and wearable antennas, achievable on laminate (rigid and flexible), and textile dielectric substrates are taken into account. The performances of small, low-profile, and dielectric resonator antennas are illustrated paying particular attention to the application areas concerning portable devices (mobile phones, tablets, glasses, laptops, wearable computers, etc.) and radio base stations. This information provides a guidance to the selection of the different antenna geometries in terms of bandwidth, gain, field polarization, time-domain response, dimensions, and materials useful for their realization and integration in modern communication systems

A Fully-Integrated Reconfigurable Dual-Band Transceiver for Short Range Wireless Communications in 180 nm CMOS

© 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.A fully-integrated reconfigurable dual-band (760-960 MHz and 2.4-2.5 GHz) transceiver (TRX) for short range wireless communications is presented. The TRX consists of two individually-optimized RF front-ends for each band and one shared power-scalable analog baseband. The sub-GHz receiver has achieved the maximum 75 dBc 3rd-order harmonic rejection ratio (HRR3) by inserting a Q-enhanced notch filtering RF amplifier (RFA). In 2.4 GHz band, a single-ended-to-differential RFA with gain/phase imbalance compensation is proposed in the receiver. A ΣΔ fractional-N PLL frequency synthesizer with two switchable Class-C VCOs is employed to provide the LOs. Moreover, the integrated multi-mode PAs achieve the output P1dB (OP1dB) of 16.3 dBm and 14.1 dBm with both 25% PAE for sub-GHz and 2.4 GHz bands, respectively. A power-control loop is proposed to detect the input signal PAPR in real-time and flexibly reconfigure the PA's operation modes to enhance the back-off efficiency. With this proposed technique, the PAE of the sub-GHz PA is improved by x3.24 and x1.41 at 9 dB and 3 dB back-off powers, respectively, and the PAE of the 2.4 GHz PA is improved by x2.17 at 6 dB back-off power. The presented transceiver has achieved comparable or even better performance in terms of noise figure, HRR, OP1dB and power efficiency compared with the state-of-the-art.Peer reviewe

Novel ring resonator-based integrated photonic beamformer for broadband phased array receive antennas - part I: design and performance analysis

A novel optical beamformer concept is introduced that can be used for seamless control of the reception angle in broadband wireless receivers employing a large phased array antenna (PAA). The core of this beamformer is an optical beamforming network (OBFN), using ring resonator-based broadband delays, and coherent optical combining. The electro-optical conversion is performed by means of single-sideband suppressed carrier modulation, employing a common laser, Mach-Zehnder modulators, and a common optical sideband filter after the OBFN. The unmodulated laser signal is then re-injected in order to perform balanced coherent optical detection, for the opto-electrical conversion. This scheme minimizes the requirements on the complexity of the OBFN, and has potential for compact realization by means of full integration on chip. The impact of the optical beamformer concept on the performance of the full receiver system is analyzed, by modeling the combination of the PAA and the beamformer as an equivalent two-port RF system. The results are illustrated by a numerical example of a PAA receiver for satellite TV reception, showing that—when properly designed—the beamformer hardly affects the sensitivity of the receiver

WIRELESS ANTENNA MULTIPLEXING USING TUNABLE ANTENNA FOR SPACE APPLICATIONS

Recent development in communication technologies shifts the communication paradigm from point to point to multi-user wireless systems. These developments eased the use of mobile telephone, satellite services, 5G cellular, smart application, and the Internet of Things. The proliferation of mobile devices has necessitated an elaborate mechanism to serve multiple users over a shared communication medium, and a multiplexing approach is introduced to serve this purpose. Multiplexing refers to a method that aims at combining multiple signals into one signal such that each user would be able to extract its desired data upon receiving the multiplexed signal. This spectrum sharing allows wireless operators to maximize the use of their spectrum to accommodate a large number of users over fewer channels. In Space applications, where sensors like temperature, attitude, IR, Magnetic, etc. send information using antennas operate at a different frequency, there is a need to collect all or some of these data using a single device. A wideband antenna requires a filtering process in order to remove unwanted signals that lead to a complex circuit design. Furthermore, the use of multiple antennas ends up with a larger size and additional complexity. Therefore, the tunable antenna is an excellent candidate which provides a perfect solution for such scenarios. A tunable antenna whose frequency characteristics shifted by applying tuning action can be used to operate as a multiplexing device that can collect signals from different surrounding antennas; each operates at a fixed frequency. A system architecture for wireless multiplexing using a tunable antenna is proposed in this project. An electronically tunable antenna using varactor diode as a tuning element is used as the multiplexing device that can collect signals from different surrounding antennas. The system consists of an RF front end and a control circuit/system for wireless multiplexing. The RF front end consists of a tunable antenna, tunable phase shifter, tunable bandpass filter, low noise amplifier, mixer, voltage-controlled oscillator, and an intermediate frequency filter. The control unit comprises a microcontroller, DAC, CMOS oscillator, power module, and a USB interface for communication with custom-built software installed on a PC. The device has functions for control, digital signal processing, and de-multiplexing. The device is fed with an input multiplexed signal, and the de-multiplexed output signals are extracted and displayed on the graphical user interface of the software. Due to the reconfigurability and programmability of the device, it presents a flexible, cost-effective solution for a variety of real-world applications