Multiple Band Operation Research Articles

Triple-wide-band Ultra-thin Metasheet for transmission polarization conversion

Polarization converters play an important role in modern communication systems, but their wide and multiple band operation to facilitate volume and size reduction is quite challenging. In this paper, a triple-band Linear Polarization to Circular Polarization (LP-to-CP) converter is presented using a novel design procedure based on geometric parameters optimization of a metasheet. The proposed converter is ultrathin, wideband, stable over a wide range of incident angles, and polarization diverse. The conductor layer of metasheet is patterned with a square ring and five square-patches diagonally intersecting each other. To validate the proposed method, an LP-to-CP convertor in X-band (7.3~9.6 GHz) and dual Ka-bands (25.4~31.4 GHz, 35.4~42.2 GHz) is presented. The performance is quite stable in wide range of frequencies and against the variation of incident angles from −25° to 25°. After performing model-based theoretical paradigm analysis, and full-wave simulation and optimization, the converter is fabricated and the measurements are performed inside the anechoic chamber. The measured results, close to simulation results, depict the validity and reliability of the proposed design.

Dual-Band Ultrathin Meta-Array for Polarization Conversion in Ku/Ka-Band With Broadband Transmission

Polarization converters play an important role in modern communication systems, but their wide and multiple band operation to facilitate volume and size reduction is quite challenging. In this letter, a dual-band linear polarization (LP) to circular polarization (CP) converter is presented using a novel design procedure based on geometric parameters optimization of a meta-array. For dual-band operation, the concept of mutual interaction of two distinct resonators is used. Step-by-step design procedure is proposed and an example is presented to convert incident x ( y ) polarization into transmitted left-hand circular polarized (LH-CP) [right-hand circular polarized (RH-CP)] in Ku band (15.15–19.5 GHz) and RHCP (LHCP) in Ka -band (33.1–39.05 GHz). After performing model-based theoretical paradigm analysis, and full-wave simulation and optimization, the converter is fabricated and the measurements are performed with a vector network analyzer. The measured results, close to simulation results, depict the validity and reliability of the design. The proposed meta-array is ultrathin, wideband, and polarization diverse, which is very suitable for wide range of applications including millimeter-wave-communication.

Design and Analysis of Dual Band Circularly Polarized Stacked Patch Antenna for GPS Application

In communications, antennas are the very important equipments are necessary to generate a communication system. Antennas are used in several applications like satellite communications etc. The design specifications of the antenna are considered using the transmission line model and designed with stacked square patches for multiple band operation with improved impedance matching. The Diagonal feed divides the given field into two orthogonal modes with equal magnitude and equal phase shift. The feed position is then optimized to attain the small axial ratio necessary to attain circular polarization at required frequency. The antenna has been designed at two different frequency bands with center frequencies of 1575 MHz and 1176 MHz. So the dual band circular polarization has been successfully incorporated into two square patches.

A Wideband Slot Antenna with Folded Parasitic Line for Multiple Band Operation

A Wideband Slot Antenna with Folded Parasitic Line for Multiple Band Operation

Multi-mode multi-band bandpass filter using hexagonal patch resonator

Resonant performances of the hexagonal resonators are analysed, and new tri-mode tri-band bandpass filter which operates at 2.5/2.8, 5.2/5.5 and 7.9/8.5 GHz with insertion loss of no more than 1.3 dB is presented by using a single fractal hexagonal resonator. It shows with fractal-shaped defection in hexagonal patch, filter performance is greatly improved and dual and tri-band bandpass filters can be implemented. The tri-band designs are demonstrated by experiment. The new hexagonal filter has outstanding advantages of multiple-band operation, miniature size, simple and compact structure without resonator coupling gaps. All these features are quite useful for applications in RF circuits.

T-SHAPED ANTENNA LOADING T-SHAPED SLOTS FOR MULTIPLE BAND OPERATION

The method of a T-shaped antenna loading T-shaped slots for multiple band operation is presented in this paper. Inspired by the fractal antenna, the proposed method is intended to be used for designing multiple band antennas. Through loading T-shaped slots in the terminals of a T- shaped antenna, dual or triple operating bands can be achieved. In order to validate the feasibility of this method, this type of antenna is designed and simulated. The antennas are respectively fed by two difierent feeding transmission lines (microstrip transmission line and coplanar waveguide (CPW) transmission line) for the purpose of identifying the method that can be commonly used. The parametric analysis in detail has been given to explain the efiects of the key parameter variations. For WLAN and WiMAX applications, the antennas are fabricated and measured. Both simulated and measured results are presented to demonstrate the feasibility of these designs.

Performance of Customizable Cut-Wire-Based Metamaterial Absorbers: Absorbing Mechanism and Experimental Demonstration

Performance of customizable cut-wire-based (CW-based) metamaterial absorbers is studied both numerically and experimentally. In the first part of the paper the fundamental absorbing performance of the CW-based metamaterial absorbers is numerically investigated. In this paper two simple geometrical modifications are proposed to easily enhance the absorbing performance: use of geometrical symmetries and wider CWs. The latter part of the paper shows an experimental demonstration of the CW-based metamaterial absorbers using a metal box lined with metamaterial absorber. The metal box has a resonant frequency which reduces the shielding effectiveness of the metal box but disappears when multiple CW absorbing elements are introduced. The absorbing performance is also confirmed by numerical simulations. The CW-based metamaterial absorbers have several important features, e.g., the simple geometry, both arbitrary enhancement and reduction of the absorbing performance and multiple band operation, which may be useful in satisfying a wide range of wave absorber applications.

Nested U -ring resonators: a novel multi-band metamaterial design in microwave region

In this study, a novel metamaterial topology, called M-band nested U-ring resonator (M-NURR), is proposed to provide multiple band operation with an electrically small and geometrically simple unit cell design. The M-NURR unit cell has M-nested and unconnected U-shaped metal rings printed on a dielectric substrate where each ring is primarily associated with a distinct LC type resonance frequency where L and C stand for inductance and capacitance, respectively. Therefore this M-NURR topology has the novel property that each of these resonance frequencies can be controlled almost independently by adjusting the arm length of the associated U-ring. In this study, three different M-NURR structures (for M=1, 2, 3) are designed, fabricated and characterised both numerically and experimentally with very good agreement. The suggested sub-wavelength M-NURR metamaterial topology is anticipated to be useful in the design of miniaturised multi-band mobile communication devices as it makes the fine tuning of operation frequencies possible by a simple parametric adjustment.

Recent results on compact broad-band and multi-band low-temperature co-fired ceramic components for radio frequency front-ends

Compact components for radio frequency (RF) front-ends realised in low-temperature co-fired ceramics (LTCC) are presented. The aim of this study was to highlight recent advances in realisation of different components for modern RF/microwave subsystems, stressing such attributes as compactness, wide bandwidth and operation in multiple bands. Two key components of every RF front-end are filters and couplers. To illustrate the feasibility of using LTCC technology to realise these components, several designs of filters and couplers are presented. Very compact LTCC ridge waveguide filter covering the whole US ultra-wide band is first discussed, followed by a dual-band LTCC ridge waveguide filter. Two types of wide-band couplers are shown: ridge waveguide couplers realised in LTCC and empty metallic waveguide and also a strip-line LTCC coupler. A common characteristic that will be shown is that the presented components by the authors are modelled using computer-aided design tools based on modal analysis for waveguides as well as commercially available finite-element tools. The shown examples have simulation results compared by different methods as well as some experimental results in LTCC and empty metallic waveguide, used to demonstrate the proposed approach.

Compact Hybrid DRA Combined with PIFA

A dielectric resonator antenna (DRA) is located below a radiating patch of an planar inverted F antenna (PIFA) to achieve a compact hybrid antenna and a multiple band operation. Loop-type structures with PIFA shorting pins are used as feeds for both the DRA and the PIFA. The proposed antenna operates well in two frequency bands without perturbing the fundamental radiation characteristics of each operating radiation mode of the DRA and the PIFA. Its electromagnetic performance and the desirable practical size of the proposed hybrid antenna are attractive for small mobile communication devices.

Multiband Scheduler for Future Communication Systems

Operation in multiple frequency bands simultaneously is an important enabler for future wireless communication systems. This article presents a new concept for scheduling transmissions in a wireless radio system operating in multiple frequency bands: the Multiband Scheduler (MBS). The MBS ensures that the operation in multiple bands is transparent to higher network layers. Special attention is paid to achieving low delay and latency when operating the system in the multiband mode. In particular, we propose additions to the ARQ procedures in order to achieve this. Deployment details and assessment results are presented for two multiband deployment scenarios. The first scenario is operation in a spectrum sharing context where multiple bands are used: one dedicated band for basic service and one shared extension band for extended services. In the second scenario we consider multiband operation in a relay environment, where the two bands have different propagation properties and relays provide extra coverage and capacity in the whole cell.