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A high gain antenna with Mu-near-zero metasurface (MNZ-MS) is introduced in this work. The proposed antenna can be utilized for future 5G applications. The patch antenna is designed on the upper face of the square substrate with a ground plane at the bottom face. To improve the antenna gain, a layer of MNZ-MS unit cells is placed above the antenna substrate with 0.48λ0 air space between the two layers, where λ0 is the wavelength in free space at the resonance frequency of 26.3 GHz. The MNZ-MS layer consists of four double-sided split square resonators. The overall thickness of the proposed antenna is 0.66λ0. To approve the execution of the proposed antenna, a prototype model is manufactured and tested. The outcomes fulfill a reflection coefficient lower than −10 dB over the frequency spectrum of 26–28 GHz. A gain improvement better than 5 dB is obtained compared to the gain of the reference patch at the center frequency of 26.3 GHz.

All textile integrated dual-band monopole antenna with an artificial magnetic conductor (AMC) is proposed. The proposed design operates at 2.4 and 5.8 GHz for wearable medical applications to monitor the heartbeat. A flexible and low-profile E- shaped CPW dual-band textile antenna is integrated with a 4 × 4 dual-band textile AMC reflector to enhance the gain and specific absorption rate (SAR). The SAR is reduced by nearly 95% at both 1 and 10 g. The design was measured on the body with a 2 mm separation. The simulated and measured results appear in high agreement in the case of with and without AMC array integration. The measurement was performed in the indoor environment and in an anechoic chamber to validate the design based on reflection coefficient and radiation pattern measurements.

In this paper, a novel metasurface-based Fabry−Perot cavity antenna loaded with toroidal metal structures is presented. The antenna is compact, wideband, and has high directivity and a high front-to-back ratio. The idea of the antenna is based on loading a microstrip narrow band patch antenna resonating at 4.5 GHz by a single layer metasurface superstrate and with a toroidal metal structure. The metasurface superstrate comprises a periodic array of square patch cells. Compared to conventional microstrip antenna, the front to back lobe ratio is increased from 7 to 20 dB and the directivity is increased by 7 dB. Also, the antenna impedance bandwidth is 34% which is increased four times. This is the first-ever antenna with enhanced bandwidth and directivity using a single layer of metasurface and that too made up of periodic cell array and has application as an energy harvester.

In this paper, for the first time, a wideband low -loss high-power equally splitting power divider based on the new half-height pin form is introduced with bandwidth from 10 to 13.5 GHz centered at...

In this work, a printed coplanar waveguide (CPW) fed single band antenna based on expanded graphite material is introduced. The proposed antenna is based on a CPW-monopole antenna with a U-shape conductor strip connected with the ground. Expanded graphite, a grade of graphene, is used as a conductor to design the uniplanar antenna over a flexible paper substrate. The antenna is designed for 2.4 GHz applications. The antenna design procedures are discussed. The material preparation and analysis are illustrated. Finally, the antenna fabrication and measurements of the reflection coefficient are discussed. The measured antenna reflection coefficient agrees with the simulated one, ensuring the antenna validity for serving the required applications. The radiation antenna parameters are discussed and simulated results from two-simulation software are included for comparison. The antenna has a simulated gain of 4 dBi and simulated efficiency of around 90% at 2.4 GHz.

In this paper, a novel high power high selective and high-Q packaged dual band air suspended stripline notch filter is presented. The notch frequencies, at 2.4 and 3.5 GHz, were designed using defected suspended stripline (DSS). Moreover, the filter was packaged and shielded using perfect magnetic conductor (PMC). The DSS were designed using two frequency independent non-coupled cascaded U shape resonators. It has been proved that the filter attenuation has a sharp rejection characteristic (measured) at the two resonance frequencies (27 dB at 2.4 GHz) and (30 dB at 3.5 GHz) with Quality factor = (18). So, the sharp measured filter attenuation performance was further enhanced to become 38 dB at the two frequencies. The achieved results are discussed and confirmed using different circuit, 3D EM and experimental measurements. The designed filter can find many medium powers up to 20 kW applications.

In this paper, a submillimetric/THz metasurface polarization/oblique independent absorber is designed and characterized. The absorber is designed using a periodic arrangement of a modified split ri...

This paper presents a compact dual-band filtering antenna without extra employing of filter structures. The antenna is designed using a planar dual-composite right/left-handed (D-CRLH) transmission line unit cell, where the filtering function is achieved through current cancellation between the D-CRLH resonators. The antenna is designed to function at 3.0 and 5.1 GHz, which can serve different WLAN applications. The antenna is a co-planar waveguide fed with a very compact size of only 30 × 16 mm2. Compared to the conventional patch antenna, the antenna size is only 17% at 3.0 GHz and 31% at 5.1 GHz. Despite the small size, the antenna preserves a good omni-directional radiation pattern at the two resonant frequencies with a measured realized gain of 2 and 2.7 dB, respectively. At the stopband in-between the two resonant bands, the reflection coefficient is almost 0 dB at 4.25 GHz and complete non-radiation is proved with a −11 dB measured realized gain. The different antenna filtering functions are verified by full-wave simulation and measurements.

In this paper, a novel metasurface-based Fabry–Perot Cavity antenna is presented. The antenna is wideband, directive and has a high front-to-back ratio. The idea of the antenna is based on loading ...

This paper presents a new diplexer design of a new-coupled composite right/left-handed (CRLH) resonator to serve the LTE applications. The realization of the diplexer is designed as coupled two zer...

An ultrathin, compact, and highly efficient antenna based on the $\Pi $ -section composite right/left-handed (CRLH) methodology is presented. It operates at 2.45 GHz of the Industrial, Scientific and Medical (ISM) band with a physical size of 25 mm $\times25$ mm, a realized gain of 2.34 dBi, and a total efficiency of 87% in free space. Nevertheless, to maintain resonance at 2.45 GHz with body-loading scenarios, a high separation was required, leading to an overall large size. To circumvent that, an all-textile $2 \times 2$ artificial magnetic conductor (AMC) array was placed in-between the antenna and the human body. In free space, the low-profile integrated design exhibited a gain of 7.63 dBi (enhancement of 5.29 dBi) and total efficiency of 96.4%. The integrated design achieved a gain and total efficiency enhancements by 14.88 dBi and 72.4%, respectively, as well as, lower specific absorption rate (SAR) levels, in comparison with the CRLH antenna alone, for human loading cases. Results are achieved through circuit model and full-wave electromagnetic simulations. In addition, the CRLH antenna and AMC array structure were fabricated and measurements were undertaken, which agreed well with the simulated ones. Therefore, the integrated design is highly suggested to be recognized in wireless body area network (WBAN) and medical applications.

The basic idea of this letter is concerned with the large Peak-to-Average Power Ratio (PAPR) problem in multi-carrier Under-Water Acoustic (UWA) communication systems that implement Orthogonal Freq...

In this paper, a wideband high-power ridge gap waveguide (RGW) T junction power divider within the frequency band from 10 to 13.5 GHz is introduced. In this configuration, the air has the ridge gap...

In this paper, a bi-directional UWB MIMO antenna is presented and investigated for superior UWB MIMO performance. The MIMO antenna elements are proved to have a typical impedance matching and direc...

Proposed is a wideband, low profile, fully flexible, and all-textile-based slotted triangular antenna loaded with a 2 × 2 textile-inspired artificial magnetic conductor to be worn on the wrist. The integrated antenna design is designed to cover the frequency band from 3.1 to 6.5 GHz. The integrated design has two main resonances, where the first one is at 3.5 GHz, which can serve the WiMAX communication standard, while the second is at 5.8 GHz, which can serve the Industrial, Scientific and Medical (ISM)-band. The incorporated textile materials are composed of the conductive and dielectric fabrics that are realized by ShieldIt and Felt, respectively. When simulated against the human model wrist, the integrated antenna design displayed a realized gain of 6.71 dBi and radiation efficiency of 79.1%, at 3.5 GHz. Furthermore, at 5.8 GHz, it displayed a realized gain of 7.82 dBi and total efficiency performances of 66.1%. Moreover, it accomplished very low SAR levels within the antenna frequency band. Averaged over 1 g of tissue, it exhibited maximum SAR levels of 3.28 × 10−6 and 9.37 × 10−7 W/kg at 3.5 and 5.8 GHz, respectively. For the bent scenarios, the integrated antenna design displayed robustness when bent at an angle of 20 and 40°. Finally, measurement results are illustrated and analyzed. Based on the presented results, the suggested all-textile integrated antenna design might be designated for integration with the wristband to monitor the user health conditions through many possible frequency channels.

An inspired metamaterial-based highly efficient monopole antenna displaying wide-/dual-band resonances along with self-filtering properties is presented. The monopole has high out-of-band suppression characteristics that lead to very close to 0 dB band-stop between the antenna dual resonant bands. The antenna operates at the two WLAN services of 2.65–3.25 and 5–7 GHz with stopband with total reflection at 4.5 GHz. The designed filtering characteristics are based on current coupling for the dual-band functions and current neutralization for the stopband function. Moreover, the proposed antenna has a very high radiation efficiency of 97 and 99% at 3 and 6 GHz, respectively. Furthermore, the proposed antenna exhibits an omni-directional radiation pattern with coplanar waveguide feed for simple integration with passive/active devices. Moreover, the antenna properties are achieved with a compact antenna size (30 × 30 mm2). With all presented results, the proposed antenna is very competitive over recent relevant antennas. In addition, a very good agreement between theoretical, full-wave simulations and measurements is achieved.

A compact monopole antenna backed with a 1 × 2 textile-based artificial magnetic conductor (AMC) array is proposed. Textile was mainly selected for the AMC materials according to an investigation that took place between different AMC substrate materials, where it was settled that the textile one displayed the highest antenna gain and efficiency. The monopole antenna and the AMC, distanced apart by 5 mm, combined form the integrated design. It operates at 2.4 GHz, which was particularly selected as the resonant frequency for wirelessly sending the subject's symptoms data via Wi-Fi, with realized gain and total efficiency of 6.76 dBi and 88.4%, respectively, in free space. Separated by 3 mm from the specific anthropomorphic mannequin human hand model, it displays a realized gain and total efficiency of 4.06 dBi and 44.39%, respectively, in a flat condition. Furthermore, it exhibits a specific absorption rate (SAR) of 1.8 W/kg averaged over 10 g of tissue. When bent over the human hand model, it performs well and exhibits a maximum SAR of 0.521 and 0.406 W/kg, averaged over 1 and 10 g of tissues, respectively. As a result of such outcomes, the proposed integrated design can be nominated for wearable hand/wrist and Wi-Fi applications.

A high gain, low specific absorption rate, oval-shaped monopole antenna is presented. It is backed by an all-textile 3 × 3 array of electromagnetic bandgap (EBG) unit cells. The antenna is printed on the thin Rogers ULTRALAM 3850 substrate, while the EBG array is composed of the conductive ShieledIT Super and dielectric substrate felt. The design operates at 2.45 GHz of the Industrial, Scientific, and Medical band. Due to the close distance between the extended grounds of the co-planar waveguide feeding configuration and the oval-shaped monopole antenna, current-coupling was achieved, leading to gain enhancement. However, with body-loading cases, resonance at 2.45 GHz was attained at a separation of 30 mm. By incorporating the EBG array, as an isolator, this issue was resolved. In free space and over a gap of 3 mm from the human body, gain enhancements by 2.68 and 11.54 dB were achieved at 2.45 GHz, respectively. Simulated and measured results are benchmarked. Furthermore, SAR simulation study showed reductions by 99.5%, averaged over 1 and 10 g of tissue.

A dual-band, low profile, high gain, and low specific absorption rate (SAR) triangular slotted monopole antenna backed with a $4\times 4$ artificial magnetic conductor (AMC) array is presented for wireless body area network (WBAN) applications. The antenna is printed on a Rogers ULTRALAM 3850 substrate, whereas the AMC array is printed on a RO3003 substrate. The design operates at 3.5 GHz, for WiMAX wireless applications, and at 5.8 GHz for the ISM Band. The proposed antenna preserved the dual-band resonance and exhibited acceptable gain and SAR at a separation of 15 mm from the human body model. To reduce such separation and achieve enhancements to gain and SAR, an AMC array was utilized. In free space, gain enhancements by 6.8 and 3.7 dBi were achieved at both frequencies, respectively. Furthermore, over a gap of 1 mm from the human body, gain enhancements by 23.3 and 13.9 dBi were achieved at both frequencies, respectively. In addition, SAR reductions by almost 99% were attained. The antenna was fabricated and measured where a very good agreement was observed between simulated and measured results, with and without the incorporated AMC array. With such results, the proposed design can be highly recommended for wearable medical applications, specifically for diabetic patients.

This paper introduces a novel design of compact tunable monopole antenna array, employing composite right/left handed (CRLH) feeding network. The feeding network configuration is coplanar waveguide...

A rectangular microstrip patch (RMSP) antenna is designed to be used in a two-element Multi-Input Multi-Output (MIMO) antennas at which they operate at 5.8 GHz. The two antennas are positioned opposite to each other with a separation of 10 mm (0.2 λ0) from their radiating edges. A novel uni-conductor electromagnetic bandgap (UC-EBG) periodic cells are introduced in this paper as effective barriers for surface waves compared to the conventional UC-EBG. Each unit cell has a compact size area 7.3 × 5.8 mm2 where it is 20% more compact than the conventional cell. Two of the proposed modified EBG periodic cells are placed in-between the two antennas causing an excellent reduction in the coupled power of 46 dB. This strong isolation definitely enhances the performance of antennas in MIMO communication systems, where 0.0001 and 0.03 values for correlation coefficient have obtained from S-parameters and far-field information, respectively, due to this strong isolation.

A high selective dual band and miniaturized electromagnetic band gap (EBG) unit cell is presented in this paper. The analysis and characterization of the new cell are explained. The modified compact EBG unit cell is based on cutting two inverted U-shaped slots inside the typical mushroom-like EBG. The modified EBG has a 70% size reduction. The dual-band functionality of the structure is confirmed by applying it in a dual-notch ultra-wideband antenna (3.1–10.6 GHz), and the notch frequencies are 5.2 and 5.8 GHz. The dual-band functionality has advantages of a highly selective bandpass between them. The antenna can suppress interference frequencies in less than 100 MHz bandwidth without affecting the antenna performance in the whole bandwidth. Presented results are addressed in terms of circuit modeling, 3D full-wave simulations, and measurements.

Here, a novel design of a planar monopole antenna is presented for wireless body area network (WBAN) wearable applications. The design is fabricated on flexible liquid crystalline polymer (LCP) substrate. The antenna is fed by a uni-planar coplanar waveguide transmission line and has total size of 51 × 22 mm 2 . In comparison with its recent published peers, the antenna has the thinnest thickness of 0.1 mm. The antenna is simulated and tested while physically bent. Proposed design along with simulation and experimental results are discussed in this work. Bottom rectangular slabs were added as a modification to the design in order to restore gain at higher frequencies. For the entire operational bandwidth, numerical far field simulations show the suitability of the proposed design to human body loading. A full study targeting specific absorption rate (SAR) has been performed to calculate the maximum input power to the proposed design. The objective has been to prevent any harm to human body as specified by the relevant international non-ionising radiation exposure standards.

A compact, flexible, coplanar waveguide-fed, U-shaped reflector surrounded asymmetric meander line antenna operating at 2.4 GHz is presented for wrist wearable applications. The antenna is printed on flexible Rogers Ultralam 3850 substrate. Size reduction of 67.7% was attained by employing the meandering methodology, in comparison with the printed straight monopole. The design displays a gain of around 3 dB by incorporating a U-shaped reflector, on the same level as the radiator, which is considered as the main contribution of the proposed design. Bending scenarios were studied proving the antenna robustness against bending. The proposed antenna was bent over a human body model with optimum separation distance, where enhancement of the specific absorption rate (SAR) level has been achieved, compared to the symmetric meander line antenna. The antenna was fabricated and measured where a high agreement was met in terms of simulated and measured return loss and radiation pattern polar plots, as well as, simulated and measured gain.

In this paper, an efficient technique proposed for surface wave filtering in radar array antennas. The filtering reduced the correlation between high directive TX/RX array antennas. The filtering has been done using a small defected ground filter that achieves more than 20 dB isolation between the two antennas with a very close separation between the two antennas (less than 0.06 λ0). The presented results confirm the advantage of the applied technique in reducing the correlation coefficient between the two antennas to less than 0.005. The results demonstrate that 99.68% of coupled power can be reduced. The integrated isolated radar array antennas have been studied theoretically, simulated using electromagnetic simulation, and measured experimentally.

In this paper, a flexible single fed planar circular polarized slot antenna is proposed for Internet of Things wideband applications. The antenna flexibility is achieved by employing a mechanically bendable liquid crystalline polymer substrate. The overall antenna volume is 50 mm × 42 mm × 0.1 mm. The antenna design uses 45° rotated elliptical ground structure for generating circular polarized radiation over wideband spectrum. Two parametrical analyses targeting the slot ground are introduced in order to achieve the most efficient design. The final antenna design demonstrates a good matching in terms of reflection coefficient (

This article presents a detailed analysis and design of an ultra-wideband (3.1 GHz – 10.6 GHz) notch antennas in a two-element MIMO system with high isolation performance. The wideband spectrum is notched at the WiMAX band at 5.8 GHz centre frequency using a highly selective electromagnetic bandgap structure coupled to the antenna feeding lines. An array of electromagnetic bandgap structure is used to achieve wideband isolation between the two elements. The two antenna elements achieve wideband reflection coefficient for good matching below -10 dB, except the notch where it becomes higher than – 2 dB. On the other hand, the antenna elements have a minimum of 20 dB isolation. Thanks to the achieved results, the antenna MIMO elements have small envelop correlation (less than 0.05) and also small channel capacity loss (less than 0.2 bit/s/Hz). The obtained results are verified using experimental measurements and all circuit/ EM needed simulations.

In this study, a resistor-loaded wideband conformal metamaterial absorber has been designed, fabricate, and analyzed experimentally. The proposed absorber consists of lumped resistors loaded on cross-shaped resonators at the top side of the flexible substrate and copper metal film separated by flexible foam on the substrate's backside. The total thickness of the absorber is 0.07λo, where λo is the lowest absorption frequency. The simulated results exhibited absorption from 3.25 - 13.6 GHz (absorption bandwidth 123%). The wideband absorption mechanism of the absorber was analyzed through the equivalent circuit model and parametric study. The designed structure has been tested on the planar and curved surfaces and measured the results. The simulated and experimental results have good agreement between them. The designed absorber can be suitable for scientific and military applications as of its wideband absorption bandwidth, polarization-insensitive, and conformability.

A compact low-pass filter (LPF) with wide rejection band based on T-type circuit of an enhanced dual composite right-/left-handed (D-CRLH) resonator is presented in this paper. The resonator has only one cell with series and parallel tank circuit. The parallel LC tank circuit has been realized by an interdigital capacitor and one shorted finger, whereas its series LC tank circuit is realized by an air gap capacitance and a short circuit stub. The filter has wide rejection band bandwidth with three transmission zeros (TZs). The filter bandwidth and TZs frequencies are controlled by the D-CRLH element values. The results of the proposed filter demonstrate minimum insertion loss in passband, high roll-off rate, and good figure of merit. The measured results are in good agreement with the simulated results. The detailed filter design is discussed in terms of circuit modeling, dispersion analysis, and full-wave simulation. Finally, the filter size is compact (0.10 λg × 0.15 λg) at cut-off frequency.

This paper presents the experimental verification of the tunable characteristics of a ferrite composite right/left handed coupled line coupler. The coupler is designed using two coupled CRLH-CRLH transmission lines. The coupler is designed to demonstrate equal through and backward coupling. The novel coupler has been designed and realized in coplanar waveguide configuration on a ferrite substrate. The tunable characteristics are achieved by changing the applied DC magnetic bias to the ferrite substrate. The measurement results reveal that the coupler’s fractional bandwidth can be tuned from 29% to 69% by varying the applied DC magnetic bias from 1000 Oe to 1750 Oe. Within the tunable bandwidth, the maximum backward coupling is −5 dB. The coupler has high forward coupling isolation, close to −30 dB at its centre operating frequency. In addition to its tuning capability, the coupler has the advantages of its compact size; it has the length of 11.5 mm and not-so-tight line separations of 2.5 mm. Furthermore the coupler only requires low DC magnetic bias.

An efficient technique to compensate for the channel detrimental effects in ZigBee systems is introduced in this paper. The proposed methodology relies on adding a recursive least square (RLS) based adaptive linear equalizer (ALE) to the physical layer of the receiver side. The performance of the RLS based ALE is investigated inside the ZigBee system under different multipath fading situations: Rician and Rayleigh. Moreover, the paper proposes a methodology for deciding the RLS based ALE’s design parameters. The design procedure depends on solving multiple objectives optimizing function based on genetic algorithms (GAs). The ALE’s parameters are chosen, such that the system experiences minimum bit error rate (BER) with fast convergence response. For design verification purposes, the ZigBee transceiver is modeled in MATLAB Simulink and tested under different fading and signal to noise ratios. In addition, the performance of the RLS adaptation algorithm is compared with the least mean square (LMS) one. The results show that the RLS based ALE provides better ZigBee performance with less BER and fast adaptation response.

In this paper, a two-element UWB MIMO antenna with bi-directional radiation pattern is designed for superior UWB MIMO performance. The designed antenna adopts asymmetric coplanar waveguide ground feeding. The proposed antenna ECC is lower than the ECC of its omni-directional peer antenna. Simulated and measured ECC is lower than 0.016 over the entire ultra-wide bandwidth (3.1–10.6 GHz). The isolation between elements of the designed antenna is 20–25 dB exceeding the average in recently published works. The designed antenna has a diversity gain of almost 10 dB and average multiplexing efficiency of 85% over the entire ultra-wide bandwidth. The antenna preserves radiation efficiency higher than 0.96 and gain 3 dB. The diversity performance of the proposed UWB MIMO antenna is proven through real rich-multipath indoor environment measurements. Stationarity of the elected channel is evaluated through 100 successive measurements separated by a 3-min period for 5 h long. The measured spatial correlation coefficients are much lower than 0.5 in different scenarios.

This study introduces a compact asymmetric coplanar strip (ACS)-fed composite right-left-handed (CRLH) multiple-input-multiple-output (MIMO) antenna for multiband operation. The ACS fed MIMO antenna is composed of two elements; each is operating at 5, 5.8 and 6.3 GHz; for different wireless applications. The overall MIMO antenna size is compact (46 × 26 mm2). A unit cell of the CRLH connected to 50 Ω ACS fed is considered the main block of the antenna. The edge-to-edge separation between antenna elements equals 0.4λ0 at 5 GHz. The insertion loss, correlation coefficient, diversity gain and channel capacity are used to evaluate the performance of the ACS-fed MIMO antenna. The isolation higher than 25 dB and envelope correlation lower than 0.05 have been achieved without using any extra decoupling structures. The experimental results are reasonably well agreed with simulated ones.

A quad band antenna with good gain and omni-directional pattern is proposed in this paper. The antenna design is based on loading a conventional monopole antenna by three different resonators. The resonators are inspired from the shunt branch of composite right-/left-handed cell. The resonators have a simple structure and compact size. The control of the frequency bands can be achieved arbitrarily and hence the suggested design methodology can be generalized to any required bands. The fabricated antenna prototype is operating at 2.6, 3.35, 5.15, and 6.1 GHz with bandwidth wider than 100 MHz for each band. The antenna's operating principle and design procedures with the aid of electromagnetic full wave simulation are presented. Finally, the experimental results exhibit good agreement with the simulated ones which confirm the proposed designed methodology. The proposed monopole antenna has a patch size of 13.5 mm × 6.5 mm and the whole antenna size (including the feed line) is 35 mm × 32 mm. Compared to conventional single-band microstrip patch radiator size, the proposed quad band radiator has the size of 9, 15, 37.5, and 72.5% at relevant frequency bands.

In this paper, the time domain analysis of an Ultra Wide Band antenna flexible circular monopole antenna is presented. The antenna is fabricated on liquid crystalline polymer flexible substrate with a compact geometry that makes it suitable for wearable applications under different bending conditions. The antenna is fed by coplanar waveguide transmission line and has a compact total size of 40 × 22 mm2. Moreover, the antenna has good radiation efficiency (97%) over the bandwidth. The presented antenna has a good performance over the operating spectrum for straight and bending configurations. The design principals along with simulation and experimental results are presented in this contribution.

A polarisation independent conformal absorber has been proposed for X-band microwave application. The absorber unit cell consists of three resonators, which generate three absorption bands at 9.1, 11.04 and 11.44 GHz with more than 90% absorption. The full wave at half maximum bandwidth of the absorber is 320 and 720 MHz at lower and upper-frequency bands. The absorber is conformal as it has a low-profile flexible substrate with an ultrathin thickness of 0.01 λ 0 , where λ 0 is the wavelength at 9.1 GHz. The proposed absorber unit cell has a fourfold symmetry, which makes the absorber polarisation independent and possesses a wide angle stability under oblique incident angle up to 50°. The absorption performance of the absorber on various radii of cylindrically curved surface has been confirmed through the simulated and measured results.

In this paper, two different triple band dipole antennas loaded by new modified composite right left handed cell are presented. The modified cell can introduce large electrical length in small size. Thus, the two antennas are designed with smaller operating frequency or reduced physical length compared to a single frequency reference dipole. The designed antennas can serve different wireless services for GPS (1.27 GHz and 1.55 GHz), UMTS (1.85 GHz), and WiFi (2.4 GHz) in triple band functionalities. The lower operating frequency antenna size is (70 × 70 mm2) whereas the reduced physical length antenna size is (60 × 70 mm2). At mid band frequencies the reduced frequency antenna length is (0.29 λ0, 0.37 λ0, and 0.52 λ0), whereas that of the reduced physical length is (0.28 λ0, 0.41 λ0, and 0.56 λ0), at triple band mid frequency, respectively. Compared to a typical dipole antenna, the designed loaded dipoles can achieve a length reduction that can reach up to 50%. Moreover, the antenna has good gain at the triple bands (−1.2 dB, 1.9 dB and 3.5 dB for reduced operating frequency antenna and −3.1 dB, 1.2 dB and 3.4 dB for the reduced length antenna. The two antennas have good radiation efficiency that can reach up to 84% on a low cost antenna substrate. The mathematical analysis, full wave simulation and experimental measurements of the reported antennas are introduced.

In this paper, a complete system for image transmission in harsh underwater environment is proposed. The key to increase the performance of the system is the use of an efficient image compression algorithm with a bandwidth-efficient modulation technique. The wavelet packet (WP) decomposition is used to get the best image representation and the set partitioning in hierarchical trees is applied on the WP coefficients. The parental conflicts are resolved, the parent–child relationships are adapted and thus the similarities between cross-subbands are preserved. Reed–Solomon is used for forward error correction to combat with the errors in wireless transmission. Orthogonal frequency division multiplexing with differential quadrature phase shift keying is used to transmit the generated bit stream. Effective image quality metrics are used for objective evaluation. Results show that the proposed system manages to transmit images over the limited bandwidth, and to effectively minimize the perceptual degradation.

This study presents the design of an electrically small metamaterial antenna with dual-band characteristics for WLAN and WiMAX applications with coplanar ground. The proposed antenna consists of stepped-impedance closed ring resonator (SICRR) and a small rectangular patch which is designed by etching a split ring resonator (SRR) from a rectangular patch which is turn fed through main feed. Such metamaterial composite exhibits dual-band behavior with first band operating at 2.45 GHz with an impedance bandwidth (|S11

In this paper, we introduce a compact dual-band two-element array antenna in a substrate integrated waveguide (SIW) configuration for C-band applications. A new geometry based on an asymmetric composite right–left-handed transmission line cells was suggested for the single antenna element. The proposed geometry has the advantage of having arbitrary dual-frequency design. The array elements are fed with a wideband SIW impedance transformer. The results indicate that the proposed antenna element size is only 15 × 12.8 mm2, which approximately represents up to 70% size reduction at similar frequencies. The radiation properties of the array antenna have broadside radiation pattern at the two bands. The detailed analytical design explanation, full wave simulations, and experimental measurements are introduced.

This study presents a hybrid electromagnetic isolation mechanism in a transceiver array antenna operating at 5.8 GHz. Maximum isolation between transmitting and receiving array antennas, at a very close spacing (3 mm = 0.058 λ 0 ), and minimum mutual coupling between each array elements is achieved without antenna radiation pattern degradation. The achieved separation is equivalent to 44% size reduction compared with conventional half wavelength spacing criterion. Each of the transmitting and receiving array antennas is a four-element linear microstrip patch array antenna. The employed hybrid isolation technique is composed of defected ground structure, to minimise coupling between array elements, and uniplanar electromagnetic bandgap, to minimise the coupling between the transmitting and receiving antennas. The resulting transceiver array antenna system fulfils -35 dB mutual coupling between array elements, and 60 dB isolation between opponent transmitting and receiving array antennas. The proposed design procedures are discussed and analysed using electromagnetic full wave simulations. Results were verified through experimental measurements for reflection coefficient, mutual coupling and radiation characteristics in which a good agreement with simulated results is granted.

This paper presents very close and high isolation composite right left handed transmission line MIMO antennas. The MIMO antennas consist of two elements each operates at 5.8 GHz for wireless applications. The two antenna elements are designed using one composite right left handed unit cell separated by only 0.034 λ0. The reduction of mutual coupling between the two antenna elements depends on current reversal between two antenna elements. The proposed MIMO antennas have the advantage of compactness (its size is only 3 × 2.6 cm2). In order to evaluate the performance of MIMO antennas, analysis of mutual coupling, correlation coefficient, diversity gain and total active reflection coefficient are presented. The proposed antennas can achieve isolation = 45 dB and envelope correlation = 0.0002 at 5.8 GHz. The simulated results are confirmed by the measurement results.