Ultra-wideband Mode Research Articles

Bandwidth and frequency agile MIMO antenna for cognitive vehicular communications

SummaryA reconfigurable MIMO antenna for heterogeneous vehicular networks is reported in this paper. The frequency and bandwidth characteristics of the MIMO antenna can be reconfigured to meet multi‐standard and multi‐frequency requirements in automobiles. The antenna element evolved from an edge‐chamfered ultra‐wideband (UWB) antenna operating from 2.1 to >15 GHz. The bandwidth reconfiguration is achieved through the selection of excitation paths connecting the feed and radiator. The feedline selection is performed using PIN diodes, making the antenna operate in three distinct modes, namely, UWB mode (Mode 1: 2.1–>15 GHz), industrial, scientific and medical/Internet of Things (ISM/IoT) mode (Mode 2: 2.45 GHz), and wireless local area network (WLAN) mode (Mode 3: 5–6 GHz). The feed path corresponding to Mode 2 and Mode 3 is incorporated with a suitable filtering network to shape the frequency response of the antenna based on the user's requirements. Owing to the requirement of cognitive selection of frequency bands, the frequency tunability in Mode 2 is realized using varactor diodes. The varactor‐incorporated feed path reconfigures the center frequency between 2.45 and 3.5 GHz. The proposed MIMO antenna offers gain and total efficiency greater than 2.94 dBi and 76%, respectively. The prototype of the 4‐port MIMO antenna is being fabricated to test its functionality in real time.

Cloverleaf filtenna with reconfigurable quintuple rejection bands using defected microstrip structure

This paper presents a quintuple-notched Filtenna based on a cloverleaf ultra-wideband (UWB) antenna and an inverted L-shaped bandstop filter (BSF). This filtenna rejects frequencies of Bluetooth (2.4 GHz), Wi-Max (3.5 GHz), Wi-Fi (5.2 GHz), ISM (5.8 GHz), and satellite communications (7.8 GHz). Using the defected microstrip structure (DMS) technique, all notches are obtained. The UWB antenna resonates over a frequency range from 2.1 to 13.6 GHz with double notches at 2.4 and 5.8 GHz, generated by etching two C-shaped DMSs on the patch. Two switches are connected to these two C- shaped slits. Controlling the ON/OFF states of these switches enables notch reconfiguration. The inverted L-shaped BSF suppresses triple notch rejections at 3.5, 5.2, and 7.8 GHz using three DMSs. Similarly, by controlling the ON/OFF states of three switches, frequency reconfiguration is observed. Simulation and measurement confirm that the UWB antenna, the BSF and the filtenna can operate in four states, eight states, and 20 states, respectively. The filtenna has good efficiency (79–95 %) and presents low radiation efficiency at rejection bands. It obtains stable gain (2–5.5 dBi) except at notches where the gain registers negative values. Additionally, this filtenna can freely switch between ultra-wideband mode and any notch-band mode.

A quad-port multiple-input-multiple-output system for underlay or interweave cognitive radio

<span lang="EN-US">This paper presents a four-element frequency reconfigurable antenna system that is novel in terms of gathering both underlay and interweave cognitive radio in a single multiple input, multiple output (MIMO) design. Built on a 50×38×0.8 mm3 Rogers RT/Duroid 5880 substrate, this system is constructed of two scanning elements to sense ultra-wide band (UWB) with controllable band notching capabilities and two elements act as communication antennas. Eighteen MIMO modes can be provided depending on the state of the five positive-intrinsic-negative (PIN) diodes in each sensing antenna and the four PIN diodes in each communication antenna. These include a scanning UWB mode, fourteen modes to notch WiMax/Cband/<a name="_Hlk120169348"></a>wireless local area network (WLAN)/Xband/ITU in single/dual/triple/quad band rejection states and three interweave modes where each targeting one of the regions of WiMax/Cband/WLAN. Simulated by CST v.10; results like input reflection coefficient and realized gain verify system's capability to work in each operation mode. Moreover, mutual coupling, envelope correlation coefficient and diversity gain all evidence the performance of the proposed system as a MIMO system. Results, simple and compact profile, wide and flexile range of MIMO operation modes in line with the novelty to handle both underlay and interweave cognitive radio all nominate this system as promising to fulfill the needs of modern wireless communications.</span>

A Low Profile Ultra-Wideband Antenna with Reconfigurable Notch Band Characteristics for Smart Electronic Systems.

This study describes the design and implementation of a small printed ultra-wideband (UWB) antenna for smart electronic systems with on-demand adjustable notching properties. A contiguous sub-band between 3-4.1 GHz, 4.45-6.5 GHz, or for both bands concurrently, can be mitigated by the antenna. Numerous technologies and applications, including WiMAX, Wi-Fi, ISMA, WLAN, and sub-6 GHz, primarily utilize these band segments remitted by the UWB. The upper notch band is implemented by inserting an open-ended stub with the partial ground plane; the lower notch band functionality is obtained by etching a U-shaped slot from the radiating structure. The basic UWB mode is then changed to a UWB mode, with a single or dual notch band, using two diodes to achieve reconfigurability. The antenna has a physically compact size of 17 × 23 mm2 and a quasi-omnidirectional maximum gain of 4.9 dBi, along with a high efficiency of more than 80%, according to both simulation and measurement data. A significant bandwidth in the UWB region is also demonstrated by the proposed design, with a fractional bandwidth of 180% in relation to the 5.2 GHz center frequency. Regarding compactness, consistent gain, and programmable notch features, the proposed antenna outperforms the antennas described in the literature. In addition to these benefits, the antenna's compact size makes it simple to incorporate into small electronic devices and enables producers to build many antennas without complications.

Reconfigurable UWB Circularly Polarized Slot Antenna With Three Modes of Operation and Continuous Tuning Rang

In this communication, a tunable circularly polarized (CP) antenna with a reconfigurable integrated feed network is proposed for cognitive radio (CR) applications. The integrated feed network is composed of an ultrawideband (UWB) bandpass filter (BPF), a continuously tunable T-shaped resonator, and an L-shaped microstrip line. The feed network employs three p-i-n diodes to switch between different RF paths, resulting in three modes of operation: an UWB mode (3.5–8.5 GHz), a narrowband bandpass (BP) mode and a narrowband bandstop (BS) mode. The continuous tuning range of the BP/BS narrowband mode is realized by two dc-controlled varactor diodes. The stand-alone antenna attains a −10 dB impedance bandwidth of 92.3% (3.5–9.5 GHz), while it attains an axial ratio (AR) bandwidth of 88.3% (3.1–8 GHz) in its wideband mode. The overlapped bandwidth (matching and AR) of the reconfigurable antenna is 78.2% (3.5–8 GHz). The communicating state covers 80% of the sensing spectrum while maintaining CP radiation. The measured peak realized gain values for the wideband mode range from 2 to 3.2 dBic while the maximum gain for the narrowband mode ranged from 1.95 to 3.1 dBic. The measured results show that the proposed filtenna is suitable for UWB CR systems.

A Bandwidth Reconfigurable Bandpass Filter for Ultrawideband and Wideband Applications

In this brief, a reconfigurable filter is proposed for simultaneous usage as ultra-wideband and wideband filters. The ultra-wideband (UWB) section is designed by constructing three parallelly connected quarter-wavelength transmission lines with two high impedance quarter-wavelength shorted stubs. The wideband (WB) section is implemented using an open stepped impedance stub-loaded resonator (OSSLR) and a shorted stepped impedance stub-loaded resonator (SSSLR). Nine pin diodes are embedded to switch the passband from UWB to WB and vice versa configuration. The filter in UWB mode produces a passband bandwidth ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$|{\mathrm{ S}}_{11}|$ </tex-math></inline-formula> dB more than 10 dB) of 9.03 GHz from 2.15 GHz to 11.18 GHz, and the WB mode reports a passband bandwidth of 2.8 GHz, which ranges from 3.25 GHz to 6.05 GHz. Further, a lowpass filter is integrated with the design to obtain a wide upper stopband. The proposed prototype is fabricated and tested to validate the collaborative design concept. The overall circuit size of the prototype is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.80\lambda _{g}\,\,\mathbf {\times }\,\,0.42\lambda _{g}$ </tex-math></inline-formula> at 4.70 GHz.

A compact UWB antenna with dynamically switchable band-notched characteristic using broadband rectenna and DC-DC booster

AbstractIn this article, a dynamically switchable ultra-wideband (UWB) planar monopole antenna employing defected ground structure (DGS) with a folded stepped impedance resonator (SIR) that can operate as either a UWB mode or the single band-notched mode is introduced. The UWB monopole antenna contains a novel whirligig-shaped radiating patch and a chambered conductor as a partial ground plane. The switchable UWB antenna uses one PIN diode as switching elements in the DGS-SIR structure without any biasing network. When the state of diode is OFF, the planar monopole antenna changes to the UWB mode, and when the diode is turned ON, a frequency notch is created at 5–6 GHz. The state of diode is set to the “ON” state dynamically in the presence of a 5–6 GHz RF signal that is detected by using a wireless power management unit (PMU) that contains a broadband rectenna and a DC-DC passive booster. The rectenna consists of a novel cypress-shaped monopole antenna as a signal receiving part and two sub-rectifiers which are connected to a 3 dB branch-line coupler with a grounded isolation port. The antenna switches from UWB to single band-notched when an RF input signal (≥8.5 dBm) in the 5.25 GHz is sensed by the RF PMU with a conversion efficiency of 26% and DC output voltage of 0.36 V, and it fades immediately in real time when the external RF signal is eliminated. In the three-tone signals, the efficiency and input signal improvements are about 10% and −5.5 dBm in the low-power levels, especially, and so develop and enhance the performance of the dynamic reconfigurability.

A Compact 8-States Frequency Reconfigurable UWB Antenna

To meet the anti-interference and multi-function requirements of the antenna, a compact 8-states frequency reconfigurable ultra-wideband (UWB) monopole antenna is proposed. The antenna consists of a coplanar waveguide structure (CPW), defected ground structure (DGS), rectangular radiation patch, and stepped feed line. Band rejections at the C band, WLAN, and X band are generated by two C-slots and inverted U-slot, respectively. Three PIN diodes are connected across the C-slots and inverted U-slot. By controlling the on/off state of PIN diodes to realize notch reconfiguration. The antenna size is only 22 mm $\times 13$ mm $\times0.8$ mm. The measured results show that the antenna can work in 8 states. The impedance bandwidth of UWB mode is 2.82-13.25 GHz, the relative bandwidth is 129.8%. The notch band is 3.19-4.58 GHz, 5.26-6.21 GHz, and 7.87-8.73 GHz, respectively. The antenna has stable gain, good omnidirectional radiation performance, and can switch freely between UWB mode and each notch band mode.

Compact UWB monopole antenna with reconfigurable band-notch characteristics

AbstractA compact ultra-wideband (UWB) monopole antenna with reconfigurable band-notch characteristics is demonstrated in this paper. It is comprised of a modified rectangular patch and a defected ground plane. The band-notch property in the WiMAX and WLAN bands is achieved by etching an open-ended slot on the radiating patch and an inverted U-shaped slot on the ground plane, respectively. To obtain the reconfigurable band-notch performance, two PIN diodes are inserted in the slots, and then the notch-band can be switched by changing the states of the PIN diodes. The antenna has a compact size of 0.47 λ1 × 0.27 λ1. The simulated and measured results indicate that the antenna can operate at a UWB mode, two single band-notch modes, and a dual band-notch mode. Moreover, stable radiation patterns are obtained.

A Reconfigurable MIMO/UWB MIMO Antenna for Cognitive Radio Applications

A novel multi-mode frequency reconfigurable MIMO and an ultrawideband (UWB) MIMO antenna design for cognitive radio applications is proposed in this paper. The antenna structure contains two modified triangular-shaped printed monopole antenna elements and a combination of varactor and PIN diodes. The proposed antenna has three operating modes: UWB mode for spectrum sensing, a frequency reconfigurable MIMO mode for communication over different frequencies, and UWB antenna operating in MIMO configuration. The UWB mode and reconfigurable communication mode are obtained by utilizing different switching ON/OFF states of PIN and varactor diodes. In the UWB mode, the antenna can cover the spectrum from 1 to 4.5 GHz, while it achieves the frequency reconfigurability over a wide range from 0.9 to 2.6 GHz using varactor diode tuning in the reconfigurable communication mode. The proposed antenna has a compact and planar structure with overall dimensions of 120 × 60 × 1.5 mm 3 . The proposed design also exhibits good MIMO performance; the minimum isolation measured is 12.5 dB, while the envelope correlation coefficient (ECC) of less than 0.19 is achieved for the whole operating band. To validate the proposed concept, the prototype of the antenna system is fabricated and measured. The simulation results are in good agreement with the measurement results.

Compact CoPlanar Waveguide-fed Ultra Wide Band and Band Switchable Slot Antenna for Cognitive Radio Front-end System

A compact coplanar waveguide (CPW)-fed ultra-wideband (UWB) slot antenna with four narrowband switchable states is presented in this paper. Cognitive Radio (CR) portable devices demand a compact antenna. In planar monopole antennas where a large space around the patch is getting wasted that can effectively be used in UWB slot antennas. The proposed antenna consists of a half-elliptical slot radiator fed through a half-elliptical shaped tuning stub to operate in the UWB mode for CR sensing. However narrowband antenna is required to operate in CR communication purpose. To operate in the narrowband mode the UWB slot antenna is fed through a defected ground structure (DGS) integrated CPW line. Frequency re-configurability is achieved by changing the DGS slot length using eight PIN diode switches. The proposed compact antenna can cover UWB frequency range from 3.14 GHz to 12 GHz. It has omnidirectional radiation pattern and also has high realized gain which is especially suited for CR front-end applications.

Half-Elliptical UWB Planar Monopole with Reconfigurable Slot Antenna for Cognitive Radio Front-End

In this paper, a half-elliptical disc ultra-wideband (UWB) monopole antenna integrated with a reconfigurable rectangular slot antenna is presented. It consists of a half-elliptical disc radiator to operate in the UWB mode whereas the etched rectangular slot on the half-elliptical patch is designed to operate as a reconfigurable narrowband slot antenna which is fed through a microstrip line from the back side of the patch. Both the antennas are placed in such a way that they are isolated to each other. Frequency reconfigurability has been achieved by inserting three lumped elements (two PIN diodes and a varactor diode) in the slot. An approximate transmission line model of the proposed slot antenna is derived to calculate the proper positioning of the diodes, and the design has been verified through numerical simulations. The simple compact proposed antenna covers a wide frequency range from 0.75 to 12[Formula: see text]GHz. Additionally, a wide tuning range from 0.8 to 2.9[Formula: see text]GHz (with the frequency ratio of 3.625:1) has been achieved. This compact integrated antenna is a good choice to be implemented in Cognitive Radio (CR) devices.

Switchable UWB/narrowband/bi‐bands octagonal antenna using PIN diodes

A reconfigurable octagonal antenna with a capability to operate in ultra-wideband (UWB), narrowband (NB) or bi-bands is presented. By incorporating two resonators, computation between the proposed modes becomes possible using the PIN diode switches. The UWB mode is obtained by deactivated the two resonators, while the one NB mode, is gotten by activated just one resonator. In the case of the activation of the two resonators at the same time, the antenna will be operating in the bi-bands mode. The prototype has been simulated and measured. Both simulation and measurement have shown the same results and characterize a reconfigurable behavior, necessary for wireless applications.

Modeling of a PIN Diode RF Switch for Re configurable Antenna Application

The paper proffers the procedure to model a PIN diode RF switch using full-wave EM solver, HFSS and utilizes the switch to built a simple partial ground plane antenna with omnidirectional radiation pattern. The proposed antenna has ability to tune it from ultra-wideband to narrowband mode. The frequency reconfigurability is accomplished by incorporating a rectangular slot resonator and a PIN diode RF switch embedded in the partial ground plane. The antenna demonstrates -10 dB impedance bandwidth from 500 MHz to 6 GHz in the ultra-wideband mode and 1.125 GHz to 2 GHz in the narrowband mode. A parasitic is stacked in the ground plane to improve the impedance matching and a rectangular slot is fused to explore the bandwidth-limiting possibility of the antenna. The optimization of the antenna is done by full-wave EM solver, HFSS and Specific Absorption Rate (SAR) of the antenna is examined using the equivalent flat tissue phantom. A prototype of the proposed antenna is fabricated and execution is accepted by measured results. The proposed antenna has simple and miniature structure, low SAR (0.41 W/Kg), omnidirectional pattern and low cross-polarization (

Compact Reconfigurable UWB Slot Antenna for Cognitive Radio Applications

A very compact reconfigurable ultrawideband (UWB) stepped-slot antenna for cognitive radio (CR) applications is presented in this letter. The proposed antenna operates in two modes: UWB mode for sensing application and communicating mode for different narrow/wideband communication applications. The UWB mode of antenna is obtained by the creation of three resonances that lie in UWB spectrum. The narrow/wide communicating bands are obtained by different switching states of five p-i-n diodes. The impedance bandwidth of the proposed antenna in UWB mode is 2.8-10.7 GHz. The communicating bands (3.2-4.5, 4.3-7.8, and 7.9-11.2 GHz) cover the entire UWB spectrum. The proposed antenna has the compact size of 21 × 9 mm 2 . A prototype of the designed antenna is fabricated and measured. The measured results are in good agreement with the simulated results that validate the proposed approach of reconfigurable UWB antenna design for CR applications.

A frequency-reconfigurable elliptical monopole antenna for cognitive radio networks

In this paper, an elliptical disk monopole antenna with seven switchable states, including an ultrawideband (UWB) state and six narrowband states, is presented. It consists of an elliptical disk radiator to operate in the UWB mode for cognitive radio (CR) sensing. To operate in the narrowband mode, the antenna is fed through a defected ground structure (DGS) integrated microstrip line. Frequency reconfigurability is achieved by changing the DGS slot length using six electronic switches. The simple proposed design can cover a wide range of frequency bands from 0.75 to 12 GHz, has an omnidirectional radiation pattern with high gain, and is especially suitable as a CR front-end. The fabricated prototype shows good impedance matching in the specified frequency range.