Reconfigurable Antennas

A compact and reconfigurable band notch UWB antenna for cognitive radio application has been proposed in this paper. The proposed UWB antenna has dual notch band in WI-max and WLAN and has reconfigurable property in terms of band notching for a single notch band in Wi-Max. Reconfigurable property of the presented antenna in WLAN band has been achieved by using a MEMS switches. The ON and OFF conditions of the MEMS switch are actually responsible to achieve the reconfigurable property. The proposed two notch bands (WI-max and WLAN) are obtained by embedding an elliptical slot on radiating patch and a rectangular strip on ground plane respectively. Empirical relations related to the proposed design for elliptical slots to obtain desired notch band have also been included in this paper. The impacts of the design parameters on notch characteristics of the antenna have also investigated. The design and functional simulation of the proposed antenna structure have performed by using HFSS-v14. A fully functional prototype has fabricated and measured and the measured results have shown a good agreement with the simulations.

International Journal of Antennas is a peer-reviewed, open access journal that publishes original research as well as review articles in the field of antennas and its allied domain. This journal aims to bring together leading academic scientists, researchers, engineers and research scholars to exchange and share their experiences and research results in their specialized arena in antenna engineering. The journal invites good quality research and review papers for publications.

The paper presents a novel bow tie quasi self complementary antenna for cognitive radio applications. The CPW
fed structure of the antenna ensures impedance matching. This antenna is designed to operate in almost the UHF band.
Here a circular bow tie antenna is converted into a wideband antenna with the help of QSC geometry and CPW feeding. The
proposed antenna shows a wide impedance bandwidth from 0.89-2.29 GHz. This antenna comprises a sensing antenna
covering almost UHF band when all the switches are off and reconfigurable/communicating antenna corresponding to
switches at various switching positions. Suitable reduction techniques are employed to reduce the size of the antenna to 86.7
x 55.5 mm which gives 24% size reduction over the conventional design.

In this paper, a compact re-configurable dual band notched wide-band antenna that is suitable for underlay and overlay UWB cognitive radio is proposed. Ultra wide-band cognitive radio (UWB-CR) features the use of UWB transmission as the enabling technology for cognitive radio, in both the underlay and overlay spectrum sharing approaches. The antenna can be operated as ultra wide-band, for underlay CR and for sensing in the overlay CR, and is re-configurable in terms of the ability to selectively have a band notch in the Wi-MAX and WLAN bands, to prevent interference to primary users operating in these bands, when used in the overlay CR mode. By etching out two CSRR of different dimensions in the radiating patch, two band-notched properties in the Wi-MAX (3-3.7 GHz), WLAN (5.125-5.825 GHz) are obtained. The realized antenna achieved an operating bandwidth (VSWR 2) ranges from 2.72 to more than 25 GHz with double notched bands of 3.3-3.82GHz and 4.79-5.8 GHz. The proposed antenna is well designed and extensively investigated. The simulation results are given to verify that the proposed antenna with a wide bandwidth is suitable for modern high data rate UWB communication applications. The maximum measured gain for the fabricated antenna is around 11.34 dBi with an average efficiency above 88.97% throughout the bandwidth.

In This study an introduction to the reconfigurable
antenna technology is presented. After that a discussion about
the main advantages and disadvantages of the reconfigurable
antenna in addition to the most important applications that can
be  used  with  the  reconfiguring  techniques,  studying  the
history  of  this  technology  with  a  brief  literature  survey  is
explained.  A detailed description  for  this  technique with
examples  and  background  information  are  specified,
reviewing  the  different  reconfigurable  antenna  components,
which can be used in an antenna to adjust its construction
and functionality. These reconfigurable antenna techniques
are  grouped  with  a  different  classification  methods  to
explain whichever established on the physical modification of
the  reconfigurable  antenna  radiating  component,  or  on  the
integration  of  micro-electro-mechanical  structures
(RF-MEMS),  varactors,  PIN  diodes,  photoconductive
components,  or  on  the  function  of  smart  materials  like
ferrites and liquid crystals, etc.

Ground station antennas are a part of TTC system, generally, Yagi-Udi antennas and Parabola dish antenna are using in Earth segment to communication with LEO small satellites, this paper uniquely presents the three huge antennas of Beihang University ground station which are communicating with some microsatellites with view window above Beijing, China. The ground station contains two Yagi-Udi antennas for VHF/UHF and an S-band dish antenna for reception of payloads data. For verification feasibility of the antennas, simulations have been accomplished according to the antennas requirements. Eventually, the simulations assisted to recognize the matched commercial ground station antennas based on comparison of the simulations with commercial antennas and the matched ones are chosen for the implementation of Beihang University ground station antennas.

The design and performance analysis of a single fed reconfigurable patch antenna for circular polarization is presented. The patch has a square shaped slot etched on it. Four ultra-miniature diode switches are placed at appropriate positions to bridge the gap in the slot regions and are used to switch the nature of polarization between left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). The antenna achieves an impedance bandwidth (S11 ≤-10dB) between 2.34 GHz to 2.4 GHz (2.53%) with a center operating frequency of 2.37 GHz. The surface current distributions on the radiating patch along with its corresponding radiation patterns measured at the operating frequency are plotted. The antenna achieves an axial ratio beam width (AR ≤ 3dB) of-25 ⁰ to 50 ⁰ for left-hand circular polarization and-40 ⁰ to 45 ⁰ for right-hand circular polarization. Measured radiation pattern results show the antenna has a good cross-polarization isolation of-16.2 dB for RHCP configuration and-16.54 dB for LHCP configurations and hence the antenna is suitable for modern wireless applications.

A narrowband corner slot patch antenna has been designed for industrial, scientific, and medical radio band (ISM band) for short distance radio communication. These antennas are analyzed and are optimized using Ansoft High-Frequency Structure Simulator (HFSS). The objective is to shrink the size of the radiating patch element without compromising antenna performance. The proposed design is investigated under various parametric analyses and are compared. The overall size of the antenna is reduced by 32.8% when compared with traditional patch antenna available in the market. This can be achieved by introducing four slots inclined at 45 0 in the radiating patch. The antenna provides a bandwidth of 25% in ISM band (|S11|≤10dB) between 2.37 GHz to 2.43 GHz. In addition, maximum Voltage Standing Wave Ratio (VSWR) value near to 1.0 and gain of 7.5 dB is achieved. Finally, good agreement has been obtained for using this proposed design for short distance radio communications.

The design of hexagonal shaped patch antenna with a narrow slot for wireless local area network (WLAN) is reported here. The slot oriented at 45 0 , in order to achieve left-hand circular polarization (LHCP). The ground is defected by cross-shaped slots oriented at 0 0 and 45 0 in order to improve the axial ratio beam width of the patch antenna. The antenna achieves reflection coefficient bandwidth (S11 ≤ 10 dB) of 6.25% (4.9–5.2 GHz) with a center frequency of 5 GHz and gives a gain of about 4.81 dB. The antenna designed is appropriate for Wireless Local Area Network (WLAN) application. A parametric analysis of ground plane slot dimension and orientation for achieving improved axial ratio beam width is carried.

Abstract—A novel design of boresight and conical pattern reconfigurable antenna with the capability of 360-degree polarization scanning is presented in this paper. At boresight mode, the antenna produces a continuously-reconfigurable polarization over 360 degrees in the azimuth plane, which provides adaptive-polarization reception between a transmitter and a receiver. The antenna is analyzed in terms of the electric field with an explanation of the generation of TM11 and TM02 resonant modes, which provides an innovative method of designing pattern-reconfigurable antennas for the WLAN applications. The proposed method is validated by a good agreement between simulated and experimental results for an antenna designed to provide boresight and conical pattern switching at 2.4 GHz. The gain of 6.05 dBi and efficiency of 86.7% are measured in the boresight mode, corresponding to 4.39 dBi and 82.4% at conical mode. Index Terms—Reconfigurable antennas, transverse magnetic (TM) mode, boresight and conical pattern, adaptive-polarization, polarization alignment.

The concept of reconfigurable antenna is widely used as an additional feature of reconfigurable ability for future wireless communication systems especially for cognitive radio applications, radar system and multi-frequency communications. There are various configurations of reconfigurable antenna such as monopole, dipole and log-periodic wideband antenna. This paper describes the design and simulation of frequency reconfigurable log periodic microstrip dipole array (FRLPMDA) using dipole patch elements with an useful frequency range for C band (4-8 GHz), X band (8-12 GHz) and Ku band (12-18 GHz). The integration of reconfigurable antennas with radio frequency (RF) switches are needed to perform the switchable ability [3-6]. In this paper, a frequency reconfigurable LPMDA has been designed to perform a wideband frequency operations by connecting fifteen dipole antennas using coaxial feed line technique. Then, the diversity in frequency is achieved by switching ON and OFF of the PIN diodes connected at every transmission line. It is compact in size and useful to support on board Radar and many wireless applications where they can reduce the size of front circuitry in communication systems.

The paper investigates single band planar resonant antenna inspired by phi-shaped slotted metamaterial superstrate and a square patch antenna is used as a primary radiator. The antenna is modeled using finite difference time domain method and resonates at S band. The antenna comprises of single layer symmetrical metamaterial superstrate which is used to suppress surface waves based on-negative characteristics. The effective material parameters of the metamaterial structure are extracted from S-parameters using Nicholson–Ross–Weir method. The antenna achieves −28.64 dB reflection coefficient of 2.4 GHz and also maintains good radiation characteristics with a peak measured gain of 7.94 dB at its operating frequency. Due to its advantages, the antenna can be used for modern wireless communications.

In this paper, micro strip patch and slot antenna are
describe. We similarly show about the reconfigurable antenna
and their types like frequency, polarization, radiation pattern
and gain. The antenna is capable of the frequency exchanging at ten different frequency between 3.4698 GHz and 6.0878 GHz.
There are design and simulate the microstrip antenna, 1X2 array patch antenna and the 1X2 array patch antenna with PIN Diodes. The outcomes are accomplished distinctive frequencies, gain, bandwidth, directivity.

A new approach for the development of tunable and reconfigurable microstrip (MS) devices is proposed. The basic idea consists of using a suspended substrate with an integrated network of plastic tubes, which can be selectively filled in with a high-permittivity dielectric fluid, e.g., water. The local change of the substrate effective permittivity achieved in such a way enables one to change, in a controlled and reversible manner, the electrical length of certain elements of MS circuits. As a proof-of-concept, tunable stub resonators based on suspended and inverted MS lines are designed and characterized in frequency and time domains. The same principle is then applied for the development of a fourth-order bandpass filter with 40% fractional bandwidth operating at 5 GHz. A tunable range of 19.5% with the insertion loss of 0.6 dB is demonstrated. The performance of the stub resonators and filter is validated successfully via prototyping.

The changing scenario of the wireless connectivity has insisted the usage of the spectrum in an efficient manner which in turn demands for the new paradigms to be adopted in practice. The Cognitive Radio (CR) termed by Joseph E Mitola III in 1999, a prominent technology to overcome the above difficulty which continuously monitors the spectrum and allocates the un used portions of the spectrum to other users in a systematic approach. The most important task in this context is the design of the antenna to cater the needs of the CR networks and they must adapt the changes in the environment and must be reconfigurable. Besides this, the major attributes that are to be considered in the context of antenna design are the low profile, low cost, weight and size considerations, ease of integration in the system, most importantly the reconfigurability and multi band behavior. The fractal antenna technology can be best fit in these environments because of their self similarity; affinity in their structure supports the wide, multi band operation and also eases the integration of switching mechanism. This paper describes a Re-configurable monopole antenna structure which consists of two hairpin band pass filters which are switched alternatively by using two separate electro mechanical Taconic switching elements. In this design, the Sierpinski monopole antenna shows the multi band behaviour and the structure resonates at four different frequencies based on its fractal geometry. However, only two frequencies within the Ultra Wide Band (UWB) frequency, 3.1 GHz-10.6 GHz range are considered i.e 3.5 GHz and 7.5 GHz for demonstrating the reconfigurability mechanism. The complete structure was designed theoretically; analyzed using CST Microwave suite simulation tool, the same was fabricated, tested and the results were reported. This structure offers higher gains with reasonably good radiation patterns along with reconfigurability in the bands of interest and can perform both the spectrum monitoring and communication mechanisms within the UWB frequency range. As the antenna structure shows the reconfigurability, independent operation at the desired frequencies, it can be employed in the Cognitive Radio applications. Keywords: ultra wide band, fractal geometries, sierpinski monopole, multi band behavior, hair pin band pass filters, re configurability, electromechanical switching, taconic switches, cst microwave studio, cognitive radio.

This paper proposes a reconfigurable microstrip patch antenna with polarization states being switched between left hand circular polarization (LHCP) and right hand circular polarization (RHCP). The CP mode has been excited by perturbation element which is a triangular slot in the circular patch. Two PIN diodes are symmetrically placed on each side of triangular slot to alter the current direction around the patch, which determines the polarization state. By changing the state of the PIN diode, the antenna has been made to switch between twp states of circular polarization. This polarization reconfigurable patch antenna covers IEEE 802.11 outdoor band and has good agile polarization performance with nearly 48MHz CP bandwidth and minimum axial ratio near to 1dB. The minimum axial ratio frequency for LHCP and RHCP are same as 5.80GHz.

Microstrip patch antennas are increasingly gaining popularity for usage in portable wireless system applications due to their light weight, low profile
structure, low cost of production and robust nature. The patch is generally made of a conducting material such as copper or gold and can take any possible shapes, but rectangular shapes are generally used to simplify analysis and performance prediction. Microstrip patch antenna radiates due to the fringing fields between the patch edge and ground plane. In this work, a frequency reconfigurable antenna with a BAR63-02V Positive-IntrinsicNegative (PIN) diode is designed, simulated and fabricated. The antenna operates at 2.686GHz for Long-Term Evolution (LTE2500) and 5.164GHz for Wireless Local Area Network (WLAN) applications. In the OFF state, the antenna operates at 5.302GHz, which is also suitable for WLAN application. The proposed antenna is fabricated on a FR-4 substrate with a relative dielectric constant, ε r  of 4.5, thickness, h of 1.6mm and loss tangent, tan δ of 0.019. The fabrication process is carried out at the Advanced Printed Circuit Board (PCB) Design Laboratory in UTHM.

A dual polarized reconfigurable printed monopole antenna excited by single feed is proposed. This structure consists of a conventional monopole antenna fed by a microstrip transmission line. On the other side of the substrate lies the ground plane in which a narrow L-shaped slot is created. The overall antenna is designed to operate at 5.8 GHz which is the wireless local area network frequency band. Using a pair of PIN diodes, one along the microstrip line and the other along the L-shaped slot, and by switching the PIN diodes, horizontal or vertical polarization can be obtained. The proposed antenna is on a FR4 substrate and has a small size of 20×35 mm 2 .

In this paper the reconfigurable patch and ground plane used as a technique for enhancing band width of microstrip antenna, traditional rectangular patch microstrip antenna is used as a comparison for result with the proposed antenna design. The design is a periodic structure on patch with defected ground plane to allow the surface wave and multi modes are excited. The result is simulated using HFSS. The bandwidth of the traditional rectangular patch antenna is about 0.13 GHz, while the proposed antenna gives us about 0.92 GHz. The proposed antenna can be used in the C-band wireless communication.

This paper presents the design of a reconfigurable planar inverted-F antenna (PIFA). The proposed antenna is designed and optimized to operate in two frequency bands. 2.4 GHz allocated to the industrial, scientific and medical (ISM) band for the identification of a set of vehicules within a given area, and 1.575 GHz allocated to the global positioning system (GPS) band to locate them outside. The ISM band is used for microwave frequencies for active radio frequency identification (RFID) tag, which is associated with the object to be identified. This antenna consists of two radiating elements connected by a positive-intrinsic-negative (PIN) diode to obtain the frequency reconfigurability. The first radiating element is connected to the ground plane by a shorting pin and excited by a 50 Ω coaxial feed line. Its total size is 30 mm × 50 mm × 7 mm. The substrate used is FR4 with constant dielectric relativity of 4.4 and a height of 1.6 mm. Computer simulation technology microwave studio (CST MWS) software is used to simulate and optimize the proposed reconfigurable PIFA antenna.

In this study, a low-profile, high directive circular microstrip antenna was designed for 5.8 GHz ISM band applications. In the design, the GA / MoM approach based on the Method of Moments (MoM) integrated with the Genetic Algorithm (GA) optimization method was used. The simulations of the best first and second antennas obtained as a result of the optimization process were made using the ANSYS HFSS software program. According to the simulation results, it was determined that the input reflection coefficient of both antennas was below -10 dB in the ISM band where the antenna was operating and had maximum directivity. It was observed that the radiation characteristics of both antennas obtained with the GA / MoM approach were steady-state in the operating band. It was concluded that asymmetric pixelation used in this method can be used in the design of antennas with different geometries.

Many wireless communication applications such as satellite communications use circularly polarized (CP) signals, with the requirement for easy switching of the polarization sense between uplink and downlink. Specifically, in satellite communications , the trend is also to move to higher frequencies and integrate the receiving and transmitting antennas in one dual-band terminal. However, these simultaneous demands make the design and fabrication of the composing parts very challenging. We propose, here, a dual-band dual-linear polarization (LP)-to-CP converter that works in the transmission mode. The working principle of this polarizer is explained through an example for Ka-band satellite communications at 19.7–20.2 and 29.5–30 GHz. The LP-to-CP converter is a single panel composed of identical unit cells with a thickness of only 1.05 mm and a size of 5.3 mm × 5.3 mm. Due to its operation in the transmission mode, the polarizer can be combined with a simple dual-band dual-LP antenna ...

— In the paper, a printed patch antenna with a rectangular slot is presented for RADAR altimeter application. The antenna is composed of single layer air substrate with double L-Shaped probe feed oriented 90 0 apart from each other and also with a shorting pin for impedance matching purpose. The measurements show that the antenna has a reflection coefficient bandwidth (S11 ≤ 20dB) of 4.6% (4.2 ~ 4.4 GHz) with a center frequency of 4.3 GHz and a gain of about 5.95 dB. The proposed antenna can be used for RADAR altimeter which are operating at 4.2 ~ 4.4 GHz band. A parametric study of geometric variation of L probe is given for clear understanding of radiation mechanism.

Coarse-grained reconfigurable fabrics (CGRF's) have great promise for achieving low-energy flexible designs for an application domain. However a universally accepted architecture for coarse-grained reconfigurable fabrics has not yet crystallized, and many architectural options are still under consideration by the research and industry community. One scientific question is how to efficiently route inputs through a CGRF. This paper addresses this question in part by exploring various alternative input solutions for a stripe-based fabric. Alternative architectural styles examined in this paper include (i) integrated constants (IC) approach where constants are loaded in the registers local to the functional units; (ii) inputs coming from the side (ICS) where both constants and variable inputs can be routed to the stripe directly where needed; (iii) ICS with extended vertical interconnect (ICS-EV); and (iv) a combination of dedicated pass gates (DPs) with standard, IC, ICS, and ICS-EV architecture styles. We implemented these architecture styles using 90 nm ASIC process from Synopsys. We perform a detailed area and energy analysis on these architectures and present quantitative results in this paper. We observed that the fabric with ICS and 50% DPs is the best among these options, providing 31% energy savings and 62% area savings over a baseline architecture for our benchmark set.

A coplanar waveguide (CPW)-fed slot antenna loaded with electronically-controlled sub-wavelength slots is introduced. This reconfigurable antenna operates at several distinct bands with appreciable bandwidth and reasonable gain. Since the antenna is tuned electronically to operate at one band at a time, it does not suffer from noise and interference issue as much as multiband and wideband antennas.

We proposed a novel antenna solution with optimized matching circuits for carrier aggregation (CA) operation. The proposed design solution provides the best performance for the CA band pair operation because it utilizes optimized matching circuits for each CA band pair combination. The antenna structure is composed of three branched monopole elements, five matching circuits, switches, and a triplexer. The five matching circuits in this proposed solution are optimized for each CA band pair, and the switches select the best matching circuits automatically. The antenna structure is three-dimensional with the size of the antenna being 50 × 5 × 3 mm3. The proposed design is compact, extending only 5 mm from the ground plane. The CA bands' mismatch loss is less than -6 dB and their isolation is less than -10 dB. The total efficiency of the CA band frequencies varies between -5 and -2 dB.

Design of a new miniaturized FF-PIFA (Folded Fractal Planar Inverted F-antenna) with dual-band resonant behavior is introduced in this paper for use in the dual-band WLAN MIMO (multi-input multi-output) applications. Firstly, the fourth iteration Koch's fractal geometry has been applied to the edges of the conventional rectangular patch structure to create a single miniaturized antenna. Then for further miniaturization, the radiating patch is folded in its sides. A substrate with relative permittivity of 2.2 and thickness of 0.9 mm has been used. The proposed antenna is located at the corner of a copper ground plane of 0.05mm thickness and dimensions of 110 × 70 mm 2. The dimensions of the single antenna are 12mm × 15mm × 6.2 mm, making it suitable for mobile terminal applications. The proposed antenna offers a dual-band resonance covering the two WLAN band standards. Modeling and performance evaluation of the proposed antenna have been carried out using the CST Microwave Studio...