WiMAX Applications Research Articles

Compact wide stopband microstrip diplexer with flat channels for WiMAX and wireless applications

This study presents a compact wide stopband microstrip diplexer which is designed based on a novel resonator structure. This novel resonator consists of a main hairpin cell loaded by a smaller hairpin and T-shaped cells. The presented diplexer operates at 3.46 and 4.75 GHz for IEEE 802.16 worldwide interoperability for microwave access (WiMAX) and IEEE802.11a Wireless LAN applications, respectively. The main advantages of the proposed diplexer are its flat channels, two wide bandwidths, attenuated harmonics, low insertion losses better than 0.18 dB, several transmission zeros and sharp frequency response. From first up to fifth harmonics of the proposed diplexer are well attenuated with the maximum harmonic level -20 dB. Meanwhile, the simulation results show that the presented design can suppress harmonics up to 44 GHz. In other words, the harmonics from the 1st up to 12th are suppressed. The group delay at both channels is lower than 1.1 ns, which is good for a microstrip diplexer. This good performance is obtained, while the overall area of the designed diplexer is only 0.037 λ g 2 . Based on the comparison results, the proposed diplexer has a compact size, the minimum group delay and a wide stopband rejection. The proposed diplexer is fabricated and measured. Both simulation and measurement results are in good agreement.

Ultra-Wideband Planar Antenna with Notched-Band for WIMAX, WLAN and MSAT Applications

Ultra-wideband (UWB) with triple band notch characteristics was presented. WIMAX, WLAN and Meteorological Satellite (MSAT) frequency bandwidths were rejected in the UWB planar antenna composed from a single layer conductor element. Frequency bandwidths for WIMAX, WLAN and MSAT are allocated at 3.3~3.7, 5~6 and 7.4~8.4GHz, respectively. Conductor element etching method was used as the means to realize the band notch characteristics as it was considered convenient and simple. Two slits were etched on the ground plane while on the elliptical element, a single slit. The slits were designed for simplicity in the means of achieving the desired band notch characteristics. The proposed antenna design was compact and low profile. The antenna performances were compared with the reference antenna and the results were negligible.

A wideband compact antenna with quad‐circular polarized bands in its operating regions

This article presents the design of an offset CPW-fed slot antenna which exhibits a narrow impedance bandwidth (IBW; |S11| ≤ −10 dB) extending from 1.20 GHz to 1.45 GHz and another wide impedance bandwidth from 1.86 GHz to 8.4 GHz thus covering almost all the conventional operating frequencies. The antenna is loaded with semicircular and rectangular stubs and meandered microstrip lines to realize circular polarization at 1.35 GHz, 3.3 GHz, 4.9 GHz, and 7.5 GHz with axial ratio bandwidth (axial ratio ≤ 3 dB) of 19.25% (1.2-1.46 GHz), 4.24% (3.24-3.38 GHz), 4.1%(4.8-5 GHz), and 5.2% (7.3-7.69 GHz) respectively thus covering the GPS, WiMAX, WLAN, and X-band downlink satellite communication application bands. The mechanism of generation of CP is discussed using vector analysis of surface current density distribution. The gain is fairly constant in the wide IBW region with maximum fluctuation of 1.2 dB. The structure is compact with an overall layout area of 0.27λ × 0.27λ, where λ is the free-space wavelength corresponding to the lowest circular polarized (CP) frequency. A comparison of the proposed antenna with previously reported structures is performed with respect to impedance bandwidth, compactness, number of CP bands, LHCP to RHCP isolation and gain to comprehend the novelty of the proposed design. A prototype of the proposed antenna is fabricated and the measured results are in accord with the simulated results.

A planar triple-band monopole antenna loaded with an arc-shaped defected ground plane for WLAN/WiMAX applications

AbstractIn this paper, a new printed triple-band planar antenna combing two different modified monopoles and an arc-shaped defected ground plane is proposed and studied. The used two simple monopoles consist of a rectangular ring and a rectangular patch attached a straight metal strip. And a compact arc-shaped defected ground structure is proposed and used to excite higher resonance frequency and improve the impedance matching of the antenna at lower and middle resonance frequencies. The main radiation element of the proposed antenna composed of only two simple monopoles can support three omnidirectional radiation modes at three desired bands. To indicate the working mechanism of the antenna, the design process is illustrated and the parametric studies are carried out. The experimental results of the fabricated prototype confirm that the triple-band antenna has better radiation efficiencies, appropriate gains, and stable omnidirectional radiation patterns. And the tested results also show that the antenna can provide enough bandwidths of 2.35–2.52, 3.2–4.16, and 5.13–5.87 GHz to cover all the desired 2.4/5.2/5.8 GHz WLAN and 3.5/5.5 GHz WiMAX operations. Moreover, the presented antenna has a very simple structure. Thus, the designed antenna has high practicality and broad prospects for WLAN and WiMAX applications.

Asymmetric Coplanar Strip-Fed with Hilbert Curve Fractal Antenna for Multiband Operations

A compact asymmetric coplanar strip (ACS)-fed with Hilbert Curve Fractal Antenna (HCFA) is proposed for GSM (1.8 GHz), WiMAX (3.3 GHz) and WLAN (5.5 GHz) applications. The proposed antenna occupies a compact size of 18 × 16.5 × 1.6 mm3 involving ACS feed line with HCFA and ground plane. A low cost FR-4 epoxy is used as a substrate material having a dielectric constant of $$\left( {\upvarepsilon_{\text{r}} } \right)$$ 4.4. HCFA consists of line sectors governed in a predictable fractal order, thus it is capable of constructing multiband and shrinkage of antenna size. MATLAB program is utilized to confirm the number of fractal order. By incorporating a suitable fractal order of HCFA, it is efficient to cover a lower resonance frequency of 1.8 GHz for attaining 90% of compactness. Experimental and simulated data are examined. The proposed antenna yields a dipole pattern in the xz plane (elevation plane) and omnidirectional pattern in the yz plane (azimuthal plane).

A novel miniaturized microstrip lowpass-bandpass diplexer using patch and interdigital cells for wireless networks

This paper presents a novel design of lowpass-bandpass microstrip diplexer using patch and interdigital cells. In comparison with the previously reported lowpass-bandpass diplexers, the proposed design has the most compact size with the overall area of 0.018 λg2 (351.7 mm2) fabricated on 0.787 mm dielectric substrate height. The lowpass channel has a cut-off frequency (fc) at 1.57 GHz. The resonance frequency of the bandpass channel is located at 3.35 GHz, which is suitable for WiMAX applications. Having low insertion losses at the lowpass and bandpass channels is another feature of this work. For the frequencies above the bandpass channel, the harmonics are attenuated up to 2.8 fc. A theory method is presented to show the behavior of the proposed structure. Finally, the designed diplexer is fabricated and measured, where the simulation results match well with the measurements.

Design of dual band four port circularly polarized MIMO DRA for WLAN/WiMAX applications

This article presents a circularly polarized 4-port Multiple Inputs Multiple Outputs dielectric resonator-based antenna with two resonating bands for WLAN (5.0 GHz) and WiMAX (3.5 GHz) applications. Important attributes of proposed MIMO-DRA are: (i) Bandwidth enhancement is observed due to the use of ring-shaped ceramic material radiator; (ii) Incorporation of rectangular aperture lead to excite the dual hybrid mode in ring DRA, which helps to support dual-frequency range (iii) Circular polarization is achieved in both operating bands by conversion of rectangular to Z-shaped slot; and (iv) mutual coupling among port <−18 dB due to the use of space diversity. The fabricated prototype of the MIMO radiator is measured experimentally, which confirms the dual impedance bandwidth of 3.35 – 3.82 GHz and 5.09 – 5.41 GHz. The proposed antenna is right-handed circularly polarized (RHCP) within the frequency range of 3.54 – 3.72 GHz & 5.04 – 5.16 GHz respectively.

Reconfigurable Quad-Band Antenna for Wireless Communication

This letter presents a thorough procedural investigation of a highly compact reconfigurable quad-band monopole antenna providing multiband operation at 1.85 GHz (GSM 1900 MHz), 2.42 GHz Bluetooth/IMTE, 3.4 GHz (Wi-MAX) and 5.3 GHz wireless LAN (WLAN) for personal wireless applications (PWA). The investigated antenna structure consists of a ‘5′- shaped stub that facilitates operation for GSM applications and a semicircular arc for Bluetooth/IMT-E applications, while an inverted L-shaped stub facilitates dual-band operation for Wi-MAX and wireless LAN applications. The presented antenna is fed using an asymmetrical coplanar strip-line (ACS) feed. The triple-band frequency reconfiguration operation, over the Bluetooth, Wi-MAX, and WLAN frequency bands, is achieved by embedding two PIN diode RF switches. The investigated antenna is developed on a highly economical FR-4 glass epoxy substrate that is 1 mm thick with a compact size of 24 × 10 mm2. The presented antenna has measured impedance bandwidths of 1.7–1.91 GHz (BW = 11.63%), 2.35–2.55 GHz (BW = 10.31%), 3.3–3.7 GHz (BW = 11.428%) and 5.10–5.6 GHz (BW = 9.345%) providing frequency reconfigurable quad-band operation at the aforementioned frequency bands. The antenna offers simulated gains of 1.8, 3.45, 4.91 and 0.86 dBi; measured gains of 2.3, 2.7, 2.82 and 2.6 dBi and radiation efficiencies of 83%, 61%, 82% and 86% at 1.85 GHz, 2.42 GHz, 3.4 GHz and 5.3 GHz, respectively. The investigated antenna exhibits nearly symmetrical radiation patterns and stable acceptable gains across all application bands, thus making the antenna suitable for wireless communication.

A closed modified V-shaped uniplanar triple band ACS fed antenna for wireless applications

In the proposed paper, a uniplanar asymmetric coplanar strip (ACS) fed antenna with closed V-shaped radiating patch of size printed on FR4 substrate with loss tangent ( =0.02, height (h)=1.6mm, and dielectric constant of 4.4 covering WiMAX, X-band and WLAN applications is presented. The proposed closed V-shaped radiating patch is formed by joning two rectangular stubs. The resultant shape of the radiating patch is obtained by adding rectangular strips to feed line until desired multiband results are achieved. The advantage of this structure is that it forms simple configuration as well as helps the overall antenna in attaining three distinict useful frequency band with good impedance matching for S11-10 dB criteria. The proposed ACS fed antenna operates at 3.1 (WiMAX), 5.0 (WLAN) and 9.9 (X-band) GHz with impedance bandwidth ranging from 2.7-3.9 GHz, 4.4-5.5 GHz and 9.5-10.3 GHz in simulation. Under measurement the proposed antenna shows multiband phenomenon at 3.2, 5.3 and 9.7 GHz with impedance bandwidth ranging from 2.8-3.7 GHz, 4.6-5.4 GHz and 9.4-10 GHz, respectively. The antenna exhibits simulated gain of 2.51, 1.18 and 1.96 dB at the corresponding frequency bands of 3.1, 5.0 and 9.9 GHz. The key parameters of the antenna like length and width of the multi-branched strips are optimized to get the multiband operation. The deisign simulation is carried out in Ansys HFSS (High frequency Simulation Software) where different characteristics of the proposed antenna are investigated. The evolution and optimization process is dealt in detail with the help of S11, VSWR, current distributions, radiation patterns and gain.

Design and Analysis of Circular Monopole antenna for WLAN and WI-Max Application in S band

In today’s existence, the technology for communication is continuously growing. The agile achievement in ultra-broadband antennas in wireless communication is increased. A circular monopole microstrip patch antenna has been developed in this research paper. The parameters grandiose by antenna perfmonance are researched. The design is designed to achieve desired gain and bandwidth at 2.4 GHz frequency, with a defected ground system (DGS). This antenna design has been effectuated using FR-4 as the dielectric substrate with 4.3 as dielectric constant. In computer simulation technology (CST) the model monopole circular microstrip patch antenna is simulated and the results needed are achieved. The S11 parameter is obtained as -17.28 decibels which is below -10 decibel. The gain obtained at 2.4 GHz frequency is 1.730 decibel. Application in S band devices, including Wi-Max, WLAN, radio altimeter, cordless phones, wireless headphones etc., were built in this research article.

Compact Novel Multiband Slotted Microstrip Patch using Grounded Asymmetric Coplanar Strip (GACS) for WLAN and WiMAX Applications

A compacted multiband antenna using grounded asymmetric coplanar strip (GACS) propounded in this paper for multiband applications. The GACS techniques is used to miniaturization of antenna. It has compact size is 19 mm × 19 mm × 1.6 mm3. The suggested antenna has been design on FR4 material with ɛr =4.4 with 1.6 thickness. The monopole antenna is modified by adding L and F strips elements in radiating structure of patch to obtain multiband band resonance. The proposed antenna has application in the bands of WLAN (2.4 GHz-2.5 GHz), Wi-MAX (3.3 GHz-3.6 GHz) and Both WLAN/Wi-MAX (5.5 GHz-5.8 GHz) band. The bandwidth of antenna getting 100MHz, 240MHz and 350MHz at 2.45GHz, 3.55GHz and 5.56GHz. All the three band has VSWR less 1.4.

Compact Wideband Meandered Slotted Multi Frequency Microstrip Antenna

A compact wideband multi frequency microstrip antenna for wireless communication is proposed in this paper. The antenna is designed by introducing meandered slot on the patch and a pair of spur lines along the triangular notch on the finite ground plane. The overall size of the fabricated antenna is very small and low profile as the total dimension is 20 × 16 mm2. The proposed antenna operates at 3.7 GHz, 4.27 GHz and 5.1 GHz which may be suitable for WiMAX and WLAN applications. In addition with multi frequency operation a wide bandwidth (VSWR ≤ 2) has been achieved from 6 to 13.7 GHz i.e. 78.2% bandwidth of center frequency, which is suitable for X-band communication and ITU band applications. The meandered slot on the patch causes multi frequency operation of the antenna with 60% compactness and the spur line along with triangular notch on finite ground plane cause bandwidth enhancement.

Super compact dual-band substrate integrated waveguide filters and filtering power dividers based on evanescent-mode technique

AbstractThis paper proposes a series of novel super compact dual-band substrate integrated waveguide (SIW) filters and filtering power dividers (FPDs) using two new compact metamaterial unit-cells. The proposed unit-cells, called COCSRRs, consist of a complementary split-ring resonator (CSRR) and an open CSRR (OCSRR). The working principle of the proposed filters and FPDs is based on the evanescent-mode technique.Based on the theory of evanescent mode, an additional passband below the waveguide cut-off can be achieved by etching the electric dipoles on the metal surface of the SIW structure. The CSRR and OCSRR unit-cells, behave as electric dipoles when excited by an axial electric field and are able to generate a forward-wave passband region below the cut-off frequency of the SIW configuration. Therefore, the proposed COCSRR unit-cells can be interpreted in term of electric dipoles, which can generate two forward-wave passbands below the cut-off frequency of the SIW structure. Although, the center frequencies of each passband can be independently controlled by changing the dimensions of the CSRR and OCSRR sections in the proposed COCSRR unit-cells. Accordingly, by loading the proposed COCSRR unit-cells on the waveguide surface, two arbitrary passbands below the waveguide cut-off frequency are achieved for WLANs and WiMAX applications. The designed SIW filters and FPD are fabricated and measured. Good agreement is observed between the simulated and measured results of the proposed filters and FPD. The proposed dual-band filters and FPD have many benefits like compact size, high selectivity, tunable passband frequencies, and easy integration with other planar technologies.

A helical shaped broadband circularly polarized dielectric resonator antenna

By modifying the shape of a rectangular dielectric resonator antenna (DRA), a wideband circularly polarized (CP) radiator is introduced. The modified structure is composed of two L-shaped dielectric pieces stacked onto each other. The resulting geometry is similar to a two-turn helix with a rectangular cross section. Placing a coaxial probe adjacent to the sidewall of the DRA excites multiple orthogonal modes in the antenna which in sequence leads to a wideband CP DRA. The special geometry of the DRA provides the required quadrature phase difference between the orthogonal components of the electric fields. The measured input scattering parameter, , is below −10 dB from 3 to 4.6 GHz (42%). Also, the frequency band in which axial ratio (AR) is lower than 3 dB extends from 3.1 to 3.83 GHz (21.07%), which is suitable for WIMAX applications. The measured results of the fabricated prototype are presented to verify the simulations.

Printed CPW-fed dual-band antenna using square closed-ring and square split-ring resonator

This paper presents the design of dual-band antenna using metamaterial structures as radiating elements. Dual resonance is obtained by making use of square closed-ring resonator and square split-ring resonator. This research develops an antenna having dimensions of 31.7 × 27 × 1.6 mm3 which operates at two bands from 2.40 to 2.50 and from 3.41 to 4.27 GHz. This antenna can be used for WLAN and WiMAX applications at 2.45-GHz and 3.5-GHz band, respectively. This paper includes necessary parametric analyses. Comparison between numerical and actual results of an antenna is given to validate the proposed design. The proposed antenna has been fabricated and tested. Good equivalence has been found between simulated and measured results. This demonstrates the applicability of the proposed antenna.

Conceptual design approach of wideband fractal dielectric resonator antenna

This study explains a novel wideband curvilinear Sierpinski fractal geometry (CSFG) based cylindrical dielectric resonator antenna. CSFG provides wider bandwidth by the combination of two important concepts: (i) reduction in volume to the surface area of the complete radiating structure, which in turn reduces the Q-factor; (ii) generation of two radiating modes inside the radiating structure HEM 11δ and TM 01δ . The prototype of the proposed antenna is fabricated for verifying the simulated results. Measured reflection coefficient (| S 11 |) shows that the proposed antenna structure operates over the frequency range 2.2–3.5 GHz with the fractional bandwidth of 45.61%. Diversified radiation pattern, i.e. monopole (due to TM 01δ mode) and broadside (due to HEM 11δ mode) is also an important feature of the proposed antenna structure. The antenna design is relevant for WLAN (2.5 GHz) and WiMAX (3.3 GHz) applications.

Mutual coupling reduction using coupling matrix based band stop filter

The capability of the coupling matrix-based band stop filter in mutual coupling reduction between the MIMO arrays is presented. Initially, a microstrip band-stop filter with 3 GHz center frequency is designed using coupling matrix method. This filter structure is then placed between 2×1 radiating patches separated by 0.22 λ in a reference MIMO antenna designed for 3 GHz WiMAX applications. Both array antennas with/without band stop filters are fabricated and the scattering parameters are obtained separately and plotted comparatively. A good agreement is achieved between measurement and simulation results, and about 28 dB isolation is observed at operating frequency after the proposed filter application. Besides, the Envelope Correlation Coefficient (ECC) is computed and surface current distributions are simulated for both cases. It is observed that ECC has dropped to almost zero and the surface currents induced in the second patch due to the first patch excitation are extinguished with the implementation of the proposed isolation wall. Finally, to clarify the advantages of our approach, a few related studies are summarized in a comparative table.

An end fire printed monopole antenna based on electromagnetic band gap structure

In this paper, a moderate gain monopole antenna is proposed for GSM and Wi-Max applications. The antenna structure is constructed from a traditional printed monopole on Roger substrate of 3006 family. To enhance the antenna performance ultimately, an Electromagnetic Band Gap (EBG) layer is introduced to the antenna structure. A numerical analysis is applied based on a Finite Integral Technique (FIT) of CST Microwave Studio (CSTMWS) formulations to characterize the EBG unit cell in terms of S-parameters, dispersion and reflection diagram, as well as the constitutive electromagnetic properties. The antenna performance is tested numerically with and without the EBG structure in terms of S-parameters and radiation patterns. It is found that the proposed antenna provides an excellent matching, S11< −10 dB, at 1.85 and 3.3 GHz with 2.88 dBi and 5.8 dBi gain, respectively. Nevertheless, the Finite Element Method (FEM) based on Ansoft High Frequency Structure Simulator (HFSS) software package is invoked to compute the antenna performance. The antenna structure is fabricated and tested experimentally. Finally, an excellent agreement is found between the obtained numerical results from both software packages and measurements.

Novel High Bandwidth Metamaterial Antenna for WIMAX and WPAN Applications in C and X-band

The performance of patch antenna loaded with H-Shape SRR with aperture feeding technique has been described in this paper. It has been proposed in an H-shaped antenna with metamaterial loading which provides a conceptual route for the implementation of small resonant antennas. We Crafted a rectangular microstrip patch antenna that has therelative permittivity 2.2 and the electrical loss tangent of 0.0009. The new antenna has wider bandwidth and increased performance in radiation. The novel antenna has compact dimensions of 4.2 mm X 5.2 mm. The simulated parameters like return loss, band width, and directivity have been done for aperture feeding at different frequencies.

Frequency reconfigurable dual-band filtenna

In this paper, a compact size frequency reconfigurable dual-band filtenna (Filter + Antenna) is proposed for WLAN, WiMaX and C-band applications. The filtenna is designed by a switchable SRR (i.e. Two switches are used in inner and outer split rings) band pass filter (BPF) and a CSRR based antenna. In the process of filtenna design synthesis process is used. The advantages of the reconfigurable filtenna structure are to reduce undesired frequency interference to the system and controllable bandwidth. The antenna is resonated at three frequencies with the bandwidth @ S11 = −10 dB i.e. 2.4 GHz (2.05–2.86 GHz), 3.46 GHz (3.4–3.55 GHz) & 4.36 GHz (4.19–4.65 GHz), whereas the filter is resonated at two frequencies i.e. 2.42 GHz (2.36–2.48 GHz) and 4.41 GHz (4.16–4.77 GHz), When both the designs (i.e. antenna & filter) are combined (i.e. Filtenna), then the joint structure allow only two resonance frequencies i.e. 2.42 GHz (2.37–2.47 GHz) and 4.41 GHz (4.24–4.69 GHz) to pass through and 3.46 GHz frequency is rejected. The rejection is occurred due to dual band filter. Due to the filteration the in band gains are 2.14 dBi and 3.39 dBi, whereas the out of band gain is −4.23 dBi, which justify its rejection behavior and does not effect system performances. Furthermore, the resonances of the resonating structures (SRR and CSRR) are justified by the lump components of the structure.In order to make the filtenna operation re-configurable, PIN diodes with DC block capacitors are connected in the inner and outer split rings of the SRR band pass filter and appropriate dc bias is applied across the PIN diodes to perform either ‘ON’ or ‘OFF’ operation. When inner ring PIN diode is ‘ON’ and outer one is ‘OFF’ then filtenna operates at 2.58 GHz (2.5–2.67 GHz). Similarly, when outer ring PIN diode is ‘ON’ and inner one is ‘OFF’ then the frequency of operation is shifted to 4.45 GHz (4.26–4.85 GHz) band. The realized filtenna at each resonance frequency exhibits bi-directional radiation pattern in E-plane and omni-directional in the H-plane. The simulated performances of the proposed filtenna is verified using the experimental results.