Design of multi band triangular microstrip patch antenna with triangular split ring resonator for S band,C band and X band applications

With the rapid advancement in multi-functional communication devices, devices capable of operating for more than one frequency bands emerged. Such applications demand for multiband antennas. Wide band antennas are capable of resonating over larger frequency bands, but it limits the impedance bandwidth and gain. So, the solution of this could be compact multi band antennas. A quad band Triangular Microstrip antenna designed for IEEE 802.16e Wi-MAX, IEEE 802.11a WLAN, C band downlink communication and x band radar applications is suggested in this work. The proposed antenna has triangular patch with triangular split ring resonator. The conservativeness and data transfer capacity are the preferred possessions of the suggested antenna. The proposed antenna yields better return and gain by resonating in 3.5 GHz, 4.1 GHz, 5.6 GHz and 9.7 GHz.     

Implementation of four-port MIMO diversity microstrip antenna with suppressed mutual coupling and cross-polarized radiations

A compact four-element MIMO microstrip antenna is designed, analyzed and proposed for high frequency modern wireless applications. Proposed antenna is compact in size and offers a frequency band of about 6 GHz ranging from 23 to 29 GHz with a peak gain of 7.1 dBi and suppressed mutual coupling and cross-polarization level. Presented antenna possess better diversity with minimum mutual coupling among its all four elements. Diversity is verified in terms of envelope correlation coefficient, directive gain, total active reflection coefficient and ratio of mean effective gain. All the diversity parameters are found within the appropriate limit standardized for a MIMO device. Experimental results of fabricated prototypes verified the proposed results.

     

Design and analysis of multiband notched pitcher‐shaped UWB antenna

To mitigate the interference with coexisting wireless systems operating over 3.3–3.6 GHz, 5.15–5.825 GHz, and 7.725–8.5 GHz bands, a novel triple band notched coplanar waveguide fed pitcher‐shaped planar monopole antenna is presented for ultrawideband applications. Bands notched characteristics are achieved using a novel mushroom type electromagnetic band gap structure like resonator and a split ring slot. A conceptual equivalent RLC (Resistor‐Inductor‐Capacitor)‐resonant circuit is presented for the band notched characteristics . Furthermore, the input impedance and VSWR (voltage standing wave ratio) obtained from the equivalent circuit are validated with simulated and measured results. Performances of the antennas in both, the frequency domain and the time domain are investigated. The simulated and measured results demonstrate that the proposed antennas have wide impedance bandwidth, nearly stable radiation patterns, and suppression of gain and total radiation efficiency at notched bands. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:795–806, 2015.     

A low‐profile quad‐port UWB MIMO antenna using defected ground structure with dual notch‐band behavior

A compact (45 × 45 × 1.6 mm³) ultrawide‐band (UWB), multiple‐input multiple‐output (MIMO) design using microstrip line feeding is presented. The proposed design comprises four elliptical monopoles placed orthogonally on a cost‐effective FR‐4 substrate. In order to improve the impedance bandwidth and lessen the return loss of the MIMO antenna, defects in ground plane are created by etching symmetrical square slots and half‐rings. Moreover, a different method (of unsymmetrical H‐shaped slot with C‐shaped slot) was proposed into the patch to introduce dual‐band rejection performance from UWB at center frequency 5.5 GHz (covering lower WLAN as well as upper WLAN) and 7.5 GHz (X band). In addition, a stub is introduced at the edge of each defected ground structure to obtain isolation >–22 dB covering entire performing band from 2 to 16.8 GHz (where, S₁₁ < –10 dB). The proposed design has miniaturized size, very low envelop correlation coefficient less than 0.1, stable gain (2‐4 dBi except for notch bands). Furthermore, various MIMO performance parameters are within their specifications, such as diversity gain (= 10 dB), total active reflection coefficient (<–5 dB, and channel capacity loss (<0.35 bits/s/Hz). The presented design is optimized using the HFSS software, and fabricated design is tested using vector network analyzer. The experimental results are in good agreement with the simulation results.     

GSM filtering of horn antennas using modified double square frequency selective surface

In this work, a dual‐band frequency selective surface (FSS) is proposed to be placed perpendicularly into the apertures of horn antennas for prefiltering 900 and 1800 MHz GSM signals interfering during the signal reception, with the enhanced return loss, gain, and directivity at the desired frequencies. For this purpose, the microstrip double square loop MDSL is modified in the first stage. As for the second stage, an FSS array (2 × 2) is built up arranging the unit MDSLs in a periodic structure and finally these FSS unit arrays are fixed perpendicularly covering the aperture of a ridged horn antenna which is a part of the available radar system operating between 0.5 and 3 GHz in our laboratory, to construct an integrated module having both bandstop prefilter and horn antenna called “filtenna.” The simulated and experimental results are agreed that the proposed FSS structure attenuates GSM signals at the 900 and 1800 MHz through the high reflection and very poor transmission mechanisms meanwhile enhances return loss characteristics, radiation pattern, and gain of the horn antenna in the desired band. Thus, it can be concluded that these simple microstrip FSS structure can be effectively adapted to the horn antennas which need the GSM prefiltering.     

Compact 2 × 2/4 × 4 tapered microstrip feed MIMO antenna configuration for high‐speed wireless applications with band stop filters

In this research, compact tapered feed 2 × 2/4 × 4 MIMO antenna are presented and investigated. The proposed MIMO antenna consists of a square patch and modified rectangular ground, which is chamfered at edges and etched with two semicircular slots. Likewise, obstruction caused by WiMAX and WLAN interfering bands is also taken care of by introducing notched filters. WiMAX is removed by embedding an rotated T‐type stub and a C‐type slot eliminates the WLAN band. The proposed antenna configuration covers the usable bandwidth of 3.07 to 11.25 GHz for 2 × 2 MIMO and 2.97 to 11.28 GHz for 4 × 4 MIMO. Also, both the MIMO antennas provide isolation <–20 dB. Proposed MIMO antennas are fabricated and characterized in near, far‐field, and diversity performance where envelope correlation coefficient, directive gain (DG), total active reflection coefficient (TARC), and channel capacity loss are simulated and measured. 4 × 4 MIMO antenna configuration provides stable gain with a maximum radiation efficiency of 91% and monopole radiation patterns.     

Design of compact multiband pattern diversity antenna for WiMax,LTE and WLAN applications

A compact multiband pattern diversity antenna for Multiple input multiple output (MIMO) applications is being proposed. The pattern diversity antenna is designed for 2.6 GHz LTE, 3.5/5.5 GHz WiMax, 3.3 GHz MIMO and 5.2 GHz WLAN applications for mobile devices. The compact size of the MIMO antenna (41.05 × 21.1 mm) is due to having compact individual monopole antennas each of dimension 17.5 × 10 mm. A T-shaped and inverted L-shaped stub in the ground plane reduces mutual coupling due to near field whereas slots introduced in the ground plane prevents current to flow through the common ground plane. The important characteristics of MIMO antenna like diversity gain and envelope correlation coefficient have also been presented. Measured and simulated radiation patterns presented show that the MIMO antenna proposed provide pattern diversity.

     

Substrate integrated low‐profile dual‐band magneto‐electric dipole antenna

In this article, a novel substrate integrated low‐profile dual‐band magneto‐electric (ME) dipole antenna is proposed. The entire antenna is constructed by four‐layer printed circuit boards (PCBs). Consequently, the height of the proposed antenna is decreased from 0.25λ₀ to 0.11λ₀ (λ₀ is the free‐space wavelength at 5.5 GHz). By introducing rectangular patches with different sizes as electric dipoles, dual operating bands are achieved. Meanwhile, for the purpose of improving the impedance matching at the lower frequency band, a pair of complementary split‐ring resonators (CSRRs) is etched on the larger rectangular patches. Moreover, the short walls composed of plated through holes operate as a magnetic dipole. The antenna is fed by an equivalent wideband microstrip‐to‐parallel stripline balun. The results show that the antenna obtains dual bandwidths of 4.31‐4.71 GHz (8.8%) and 5.07‐5.89 GHz (14.9%) with VSWR <2, which can be applied for C‐band and 5G WiFi. Over the dual operating bands, stable gain and unidirectional radiation patterns with low polarization and low back lobe are also obtained.     

Pattern squint elimination for quad‐ridged conical and pyramidal horn antennas using bended probes

This article describes a new technique for pattern squint elimination of quad‐ridged conical and pyramidal horn antennas by introducing bended coaxial probes. Because of the phase difference and mutual coupling between vertical and horizontal polarizations, the radiation patterns of the conventional quad‐ridged conical and pyramidal horn antennas squint over a wide bandwidth. The proposed technique substantially reduces the phase difference and coupling between the two probes, so a significant improvement in the radiation patterns over the frequency band of 8–18 GHz can be achieved. The designed modified horn antennas are most suitable as a feed element in reflectors of radar systems and EMC applications. The proposed modified antennas have a voltage standing wave ratio (VSWR) less than 2.2 for the frequency range of 8–18 GHz. Moreover, the proposed antennas exhibit high gain, dual‐polarization performance, good isolation, low SLL, low back lobe, low cross polarization, and satisfactory far‐field radiation characteristics for the entire frequency band. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE 2010.     

Dual‐polarized textile‐based two/four element MIMO antenna with improved isolation for dual wideband application

This article presents the designs of dual‐polarized dual wideband textile‐based two and four elements multiple‐input multiple‐output (MIMO) antennas for WLAN (IEEE 802.11a/b/g/c/n) and WiMAX (IEEE 802.16d) applications. These MIMO antennas cover the frequency spectra from 1.5 to 3.8 GHz (87% bandwidth) and 4.1 to 6.1 GHz (40% bandwidth). The characterization of the textile jeans substrate is determined experimentally using a vector network analyzer and dielectric assessment kit. These antennas provide near about 70% radiation efficiency with around 4 dBi peak gain in desired frequency ranges. The diversity performance is improved noticeably by printing meandered line structures on both planes. The proposed MIMO structure has a very low envelop correlation coefficient (ECC) <0.1 and high diversity gain (DG) >9.9. The Medium effective gain (MEG) also lies within a satisfactory value of ±3 dB. The two elements MIMO Antennas provide linear polarization at all desired frequency band while the four‐element antenna provides circular polarization at 2.4 GHz and linear polarization at 5.2 and 5.8 GHz application bands. The antenna also depicts good performance in wearable condition with safe specific absorption rate < 1.6 W/kg in all desired frequencies.     

Design of conical DRH antennas for K and Ka frequency bands

Two conical double‐ridged horn (DRH) antennas for K and Ka frequency bands are presented. Detailed simulation and experimental investigations are conducted to understand their behaviors and optimize for broadband operation. The designed antennas were fabricated with 0.01 mm accuracy and satisfactory agreement of computer simulations and experimental results was obtained. The designed conical DRH antennas have voltage standing wave ratio (VSWR) less than 2.1 and 2.2 for the frequency ranges of 18–26.5 GHz (K band) and 26.5–40 GHz (Ka band), respectively. Meanwhile, the proposed antennas exhibit low cross‐polarization, low sidelobe level, and simultaneously achieve slant polarization as well as symmetrical radiation patterns in the entire operating bandwidth. An exponential impedance tapering is used at the flare section of the horns. Moreover, a new cavity back with a conical structure is used to improve the VSWR. Numerous simulations via Ansoft HFSS and CST Microwave Studio CAD tools have been made to optimize the VSWR performance of the designed antennas. Simulation results show that the VSWR of the proposed antennas is sensitive to the probe spacing from the ridge edge and the cavity back structure. The designed conical DRH antennas are most suitable as a feed for the reflectors of radar systems and satellite applications. Results for VSWR, far‐field E‐plane and H‐plane radiation patterns, and gain of the designed antennas are presented and discussed. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

Dual polarized triple band hybrid MIMO cylindrical dielectric resonator antenna for LTE2500/WLAN/WiMAX applications

In this communication, triple band hybrid multi‐input–multi‐output (MIMO) cylindrical dielectric resonator antenna (CDRA) with high isolation is examined. The proposed MIMO antenna includes two symmetric folded microstrip line feeding structures along with CDRA at two different ends of substrate. Two inverted L‐shaped strips on the ground plane are used to enhance the isolation (S₁₂ < ?15 dB) as well as to generates 2.7 GHz frequency band. Metallic strip on the ground plane act as an electromagnetic reflector and also enhance the isolation between two antennas (S₁₂ < ?20 dB). Archetype of proposed MIMO antenna design has been fabricated and tested to validate the simulated results. The proposed antenna operates at three different frequency bands 2.24–2.38 GHz, 2.5–3.26 GHz, and 4.88–7.0 GHz (S₁₁ < ?6 dB) with the fractional bandwidth 6.06%, 26.4%, and 35.7%, respectively. Folded microstrip lines generate path delay between the electric field lines and originate circular polarization characteristics in the frequency range 5.55–5.75 GHz with the fractional bandwidth of 3.55%. In order to satisfy the different performance requirement of MIMO antenna such as envelop correlation coefficient, mean effective gain, effective diversity gain, peak gain are also examined. The proposed antenna is found suitable for LTE2500, WLAN, and WiMAX applications. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2016.     

Double‐ridged conical horn antenna for wideband applications

In this article, the design and analysis of a double‐ridged conical horn antenna with high gain and low cross polarization for wideband applications is presented. Double‐ridged pyramidal horn antennas have been investigated in many references. There are no papers in the literature which are devoted to design and analysis of double‐ridged conical horn antenna. The designed antenna has a voltage standing wave ratio (VSWR) less than 2.1 for the frequency range of 8–18 GHz. Moreover, the proposed antenna exhibits extremely low cross polarization, low side lobe level, high gain, and stable far‐field radiation characteristics in the entire operating bandwidth. A new technique for synthesizing of the horn flare section is introduced. A coaxial line to circular double‐ridged waveguide transition is introduced for coaxial feeding of the designed antenna. The proposed antenna is simulated with commercially available packages such as CST microwave studio and Ansoft HFSS in the operating frequency range. Simulation results for the VSWR, radiation patterns, and gain of the designed antenna over the frequency band 8–18 GHz are presented and discussed. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

Double triangular monopole‐like antenna with reconfigurable single/dual‐wideband circular polarization

A polarization and frequency reconfigurable circularly polarized (CP) antenna is proposed based on a novel bilateral switching mechanism. Two triangular monopole antennas are connected to each other in an L‐shaped form by a narrow link to produce a CP operation. In the proposed technique, 4 PIN‐diode‐based switches are designed with desired insertion loss and isolation, and only 2 DC‐voltage controllers. These switches are located on the links and the feed lines to realize a polarization reconfigurable feature including both right‐hand CP (RHCP) and left‐hand CP (LHCP) modes. Moreover, 2 CP states, a single wideband operation and a dual‐band operation, can be supported by this mechanism. In a special performance of the switches, CP reconfigurability can be obtained in a narrow‐band mode around 2.45 GHz. Two general simulations are performed based on the simple microstrip links and a diode‐circuit model. The measured results exhibit a wide overlapped bandwidth (AR < 3 dB and VSWR < 2) of 44.4% (1.63–2.56 GHz) with a peak gain of 2.88 dBi in the first state and 5.5% (1.22～1.29GHz) and 20.6% (2.12–2.61 GHz) with the peak gains of 0.52 and 3.0 dBi in the second state, respectively. A wide beamwidth is obtained more than 75°. This work is appropriate for L‐ and S‐band CP diversity applications.     

A compact printed ultra‐wideband multiple‐input multiple‐output prototype with band‐notch ability for WiMAX,LTEband43, and WLAN systems

A compact ultra‐wideband multiple‐input multiple‐output (UWB‐MIMO) antenna with good isolation and multiple band‐notch abilities is developed in this work. It consists of two quadrant shaped monopole antennas backed by ground stubs. A good isolation is achieved due to the two proposed extended curved ground stubs. The frequency rejection for the WLAN system is realized by loading a capacitive loaded loop resonator adjacent to the feed line. The band rejection for the WiMAX and LTE band43 system is achieved by embedding a quadrant shaped CSRR on each radiator's surface. The measured bandwidth of the antenna is 3.06 GHz‐11 GHz (|S₁₁| < ?10 dB and |S₂₁| < ?18 dB) with a band rejection from 3.5 GHz‐4 GHz to 5.1 GHz‐5.85 GHz, respectively. Time domain performances are investigated in terms of group and phase delay characteristics. Diversity characteristics are evaluated in terms of the envelope correlation coefficient, mean effective gain, and channel capacity loss.     

Design of a printed log‐periodic dipole array antenna with high gain for millimeter‐wave applications

In this article, a V‐band printed log‐periodic dipole array (PLPDA) antenna with high gain is proposed. The antenna prototype is designed, simulated, fabricated, and tested. Simulation results show that this antenna can operate from 42 to 82 GHz with a fractional impedance bandwidth of 64.5% covering the whole V‐band (50–75 GHz). The antenna has a measured impedance matching bandwidth that starts from 42 to beyond 65 GHz with good agreement between the experimental and simulated results. At 50 and 65 GHz, the antenna has a measured gain of 10.45 and 10.28 dBi, respectively, with a gain variation of 2.6 dBi across the measured frequency range. The antenna prototype exhibits also stable radiation patterns over the operating band. It achieves side‐lobe suppression better than 17.26 dB in the H‐plane and better than 8.95 dB in the E‐plane, respectively. In addition, the cross‐polarization component is 18.5 dB lower than the copolarization with front‐to‐back ratio lower than 24.1 dB in both E‐ and H‐planes across the desired frequency range. Based on a comparison of performance among the reported work in the literature, we can say that the proposed PLPDA antenna is a proper candidate to be used in many applications at V‐band frequency. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:185–193, 2015.     

Novel square slot circularly polarized antenna with broadband characteristics

In this article, a novel wideband circularly polarized (CP) square-slot antenna with perturbation elements is proposed. The antenna comprises of an inverted L-shaped feeding line, pairs of corner cuts, a rectangular slot, and a semi-elliptical patch. The numerous CP resonant modes were excited simultaneously using these slots and patches as perturbation elements. To verify this concept, an antenna prototype was built and tested. The measured results indicate the ?10-dB impedance bandwidth (IBW) is 69.2% (2.42–4.98, 3.7 GHz) and 3-dB axial ratio bandwidth (ARBW) is 59% (2.58–4.74, 3.66 GHz). Furthermore, the measured peak gain is 4.3 dBi, and the gain variation within the certain bandwidth is less than 1 dB. Therefore, the presented antenna features wide CPBW and stable gain characteristics.     

A wideband compact horizontally polarized omnidirectional antenna for 2G/3G/LTE

A compact horizontally polarized omnidirectional slot antenna with a wide working band is presented in this article. The proposed antenna consists of 4 shorter driven cross‐shaped slots, 4 longer parasitic cross‐shaped slots, and a feeding network. Four shorter slots, placed on the same side of a circular substrate, are fed by a feeding network printed on the other side with uniform phase and magnitude. To enhance the bandwidth of the antenna, 4 longer cross‐shaped slots are inserted between adjacent longer slots to produce an additional resonant frequency. All 8 slot radiators placed symmetrically along the circumference results in an omnidirectional horizontal polarized radiation pattern. By utilizing cross‐shaped slots, a compact size of 0.53λ_L × 0.53λ_L × 0.005λ_L (λ_L is the free space wavelength at the lowest operational frequency) is achieved. The prototype of the proposed antenna is fabricated and measured. The measured results reasonably agree with the simulated results. The measured working band for |S₁₁|<–10dB is from 1.62 to 2.81 GHz which successfully covers the 1.7 to 2.7 GHz 2G/3G/LTE bands. The measured gain variation in azimuthal angle is <1.7 dB within 1.7 to 2.7 GHz, and the cross polarization level is <–27 dB in the horizontal plane.     

Design of a microstrip fed printed monopole antenna for bluetooth and UWB applications with WLAN notch band characteristics

In this article, a microstrip fed printed dual band antenna for Bluetooth (2.4–2.484 GHz) and ultra‐wide band (UWB; 3.1–10.6 GHz) applications with wireless local area network (WLAN; 5.15–5.825 GHZ) band‐notch characteristics is proposed. The desired dual band characteristic is obtained by using a spanner shape monopole with rectangular strip radiating patch, whereas the band‐notch characteristics is created by a mushroom‐like structure. The Bluetooth and notch bands can easily be controlled by the geometric parameters of the rectangular strip and mushroom structure, respectively. The proposed antenna has been designed, fabricated, and tested. It is found that the proposed antenna yields both the Bluetooth and UWB performance in the frequency regions of 2.438 to 2.495 GHz and 3.10 to 10.66 GHz, respectively for |S₁₁| ≤ ?10 dB with an excellent rejection band of 5.14 to 5.823 GHz to prevent WLAN signals. The experimental results provide good agreement with simulated ones. Surface current distributions are used to analyze the effects of the rectangular strip and mushroom. The designed antenna exhibits nearly omnidirectional radiation patterns, stable gain along with almost constant group delay over the desired bands. Hence, the proposed antenna is expected to be suitable for both Bluetooth and UWB applications removing the WLAN band. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:66–74, 2015.     

Performance enhancement of nested hexagonal ring‐shaped compact multiband integrated wideband fractal antennas for wireless applications

In this paper, nested hexagonal ring‐shaped fractal antennas are designed and investigated which are different from each other in patch orientation. Initially, the multiband integrated wideband hexagonal nested ring antenna is designed (antenna‐I). To improve the multiband/wideband behavior, the patch orientation of antenna‐I is changed to ?60°/60° (antenna‐II), ?120°/120° (antenna‐III), and ?180°/180° (antenna‐IV). Antennas are designed on low cost FR‐4 glass epoxy substrate with relative permittivity of 4.4 and overall dimension 30 × 30 × 1.6 mm³. Comparison among antennas have been made and found that the antennas with negative orientation exhibit better results in terms of bandwidth, impedance matching, number of frequency bands, and gain. Designed antennas have been compared with each other and found that antennas‐II and III are better in performance as compared to antennas‐I and IV. Antenna‐II exhibits wider bandwidth of 1.26 (2.52‐3.78 GHz), 2.75 (4.03‐6.78 GHz), and 6.1 GHz (7.82‐13.92 GHz) with maximum gain of 7.14 dB. Similarly; antenna‐III exhibits the bandwidth of 340 MHz (1.92‐2.26 GHz), 820 MHz (3.04‐3.86 GHz), 4230 MHz (5.38‐9.61 GHz), and 3040 MHz (10.41‐13.45 GHz) with a maximum gain of 6.19 dB. Prototype of the designed antennas with satisfactory orientations are fabricated and tested for the validation of results. Simulated and measured results are also juxtaposed and observed in good agreement with each other. Antennas exhibit bidirectional and omnidirectional pattern in E‐plane and H‐plane, respectively, also the radiation efficiency of antennas are in acceptable range from 75% to 95%. Due to the wider bandwidth of designed antennas, they can be used for different wireless standards such as Advance Wireless Services AWS‐1, AWS‐2, AWS‐3, Wi‐MAX, WLAN, X‐band satellite communication, point‐to‐point wireless applications, ITU band, military satellite communication, television broadcasting, and military land and airborne systems.