A Dual-Band Base Station Antenna with a Split Ring for Sub-6 GHz Communication

A dual-band base station antenna is introduced in this paper. The proposed antenna is composed of baluns, bowtie patches, and a split ring. The two pairs of bowtie patches excited by the two orthogonal balun structures can achieve dual polarization. The split ring is used to yield two additional resonances to broaden the impedance bandwidth. In this way, a compact dual-band base station antenna is obtained with the size of 0.41 λc × 0.41 λc × 0.13 λc (λc is the wavelength in the free space at the lowest operating frequency band) and the average gain of 8.2 dBi. Moreover, the operating frequency bands of the proposed antenna cover 2515–2675 MHz, 3400–3600 MHz, and 4800–5000 MHz, which can function as an element for macro- or microcells in sub-6 GHz communications.

Improving The Ability To Recognize Age Of Children Early Through Media Wheels Rotate In Group A At Tk Dharma Wanita Sugihwaras Temple

The Capability to recognize number symbols plays an important role in children's lives because with the ability to recognize number symbols we can calculate something. The activity of recognizing number symbols is an activity to count which is carried out using various media such as, Spining Whells. The purpose of this study is to improve the ability to recognize early childhood number symbols in group A at TK DHARMA WANITA SUGIHWARAS CANDI. This type of research is classroom action research. Based on the data analysis carried out, it was concluded that the children's fine motor skills in the pre-cycle obtained an average value of 54.70% while the first cycle obtained a percentage of 66.66% which meanthat it was not optimal. Then give action in the second cycle, the percentage of the average value of the child becomes 82.05%, so that from the average gain in the first cycle and second cycle there is an increase of 15.39%. The conclusion of this study is that through spinning whells can improve the ability to recognize the symbols of numbers.

Reconfigurable 2×1 CPW-Fed Rectangular Slot Antenna Array (RSAA) Based on Graphene for Wireless Communications

This article presents a 2×1 CPW ultra wideband rectangular slot antenna array (UWB-RSAA) with a modified circular slot shape to support a high data rate for wireless communications applications. The proposed antenna array dimensions are 0.7λ×0.8λo×0.064λo at the resonant frequency 1.8 GHz. It is fabricated on Rogers RO4003 substrate and fed by using a coplanar waveguide (CPW). A graphene layer is added on one side of the substrate to realize frequency reconfigurability and improve the array gain. The proposed array acquires -10 dB impedance bandwidth of the RSAA that extends from 1.7 GHz to 2.6 GHz, from 3.2 to 3.8 GHz, and from 5.2 GHz to 7 GHz. The proposed array achieved a realized peak gain of 7.5 dBi at 6.5 GHz at 0 Volt bias with an average gain of 4.5 dBi over the operating band. When the graphene bias is increased to 20 Volt, the antenna bandwidth extends from 1 GHz to 4 GHz and from 5 to 7 GHz with a peak gain of 14 dBi at 3.5 GHz and an average gain of 7.5 dBi. The linearly polarized operation of the proposed array over the operating bands makes it suitable for short-range wireless communications .

A Low-Profile Broadband Circularly Polarised Wide-Slot Antenna with an Artificial Magnetic Conductor Reflector

In this letter, a novel broadband circularly polarisation (CP) wide-slot antenna with an artificial magnetic conductor (AMC) as the reflector is presented. The wide-slot antenna is composed of a knife-shaped radiator and an improved ground plane. A broadband CP characteristic can be achieved by slotting the ground plane to make it an asymmetric ground shape. However, the average gain of the wide-slot antenna is only about 3 dBic because of bidirectional radiation. An AMC reflector is adopted to enhance the gain of the wide-slot antenna without introducing a high profile similar to the PEC reflector. In addition, the four metal plates are vertically placed around the antenna to broaden the axial ratio (AR) bandwidth of the antenna with the AMC reflector. The measurement results show that the 3dB AR bandwidth of the proposed CP antenna is 32.4% (2.35GHz─3.26GHz), the average gain is 6.5dBic in the AR bandwidth and the value of VSWR in the AR bandwidth is less than 2. The size of the antenna is 0.84λ0× 0.84λ0× 0.13λ0 at the centre frequency of 2.805 GHz. The proposed antenna has a low profile, broad AR bandwidth and high gain, thereby being a good candidate for various wireless communication systems.

Reconfigurable 2×1 CPW-Fed Rectangular Slot Antenna Array (RSAA) Based on Graphene For Wireless Communications

This article presents a 2×1 CPW ultra wideband rectangular slot antenna array (UWB-RSAA) with modified circular slot shape to support high data rate for wireless communications applications. The proposed antenna array dimensions are 0.7λo×0.8λo×0.064λo at the resonant frequency 1.8 GHz and it is fabricated on a commercially available rogers RO4003 substrate (with εr = 3.5), which is fed by using coplanar waveguide (CPW). A graphene layer is added on the other side of the substrate to achieve frequency reconfigurable and improve the antenna array gain. The -10 dB impedance bandwidth of the RSAA extends from 1.7 GHz to 2.6 GHz, from 3.2 to 3.8 GHz and from 5.2 GHz to 7 GHz with peak gain of 7.5 dBi at 6.5 GHz at 0 Volt bias over the operating band with average gain of 4.5 dBi. When the graphene bias is increased to 20 Volt, the antenna bandwidth extend from 1 GHz to 4 GHz and from 5 to 7 GHz with array peak gain 14 dBi at 3.5 GHz and average gain 7.5 dBi. The proposed array achieved linear polarized behaviour over the operating bands to be suitable for short range UWB wireless communications and object detection. All simulation carried out using 3D high frequency structure simulator (HFSS) Ansys ver. 15.

Cervical cerclage or not in delayed delivery interval: obstetric management and outcomes

Objective The aim of this study is to explore the effectiveness of cervical cerclage in order to delay the delivery interval after delivery of the first fetus in dichorionic twin pregnancies. Study Design: Records of 11 twin pregnancies where delayed delivery was experienced for retained fetus(es), were collected retrospectively. Cases with cervical cerclage placed after the first delivery were evaluated as the cerclage group and cases without cerclage placement were evaluated as the non-cerclage group. Results The median duration of the delay 25.4 ± 8.1days (range, 4–50) in the cerclage group and 7.7 ± 2.0 days(range, 3–17) in the non-cerclage group (P = 0.045). Average gain birthweight of the second fetus in the cerclage group was 408.0 ± 160.2 g and 93.3 ± 25.5g in the non-cerclagegroup(P = 0.061). But other parameters were not different between the two groups. Conclusions Cervical cerclage after the first delivery is associated with a longer inter-delivery interval without increasing the risk of intrauterine infection.

Pengaruh Model Pembelajaran Snowball Throwing Terhadap Minat Belajar Geografi Siswa SMA Negeri 2 Labuapi

This study aims to describe the effect of the Snowball Throwing learning model on the learning interest of students at SMA Negeri 2 Labuapi in Geography. This research method using experiment. The research sample was taken from class XII IIS 1 as a control class consisting of 25 students and class XII IIS 2 as an experimental class of 27 students. The research instrument was a questionnaire of interest in learning geography which consisted of a pre-test and a post-test questionnaire. Based on the results of the study, there is a difference in interest between the experimental class that uses the snowball throwing learning model and the control class that uses lectures and questions and answers with sig (2-tailed) 0.000 <0.05, so that H0 is rejected and H1 is accepted, which means there is a difference in interest in learning geography. control class and experimental class. The average gain score for the experimental class was higher than that of the control class, namely 16.59> 3.08. This indicates that there is an effect of the snowball throwing learning model on the students' interest in learning geography in class XII SMA Negeri 2 Labuapi.

Widely Flatness Gain Bandwidth with Double Pass Parallel Hybrid Fiber Amplifier

A Widely flatness gain bandwidth with double pass parallel hybrid fiber amplifier is experimentally demonstrated in this study. The proposed design combines serial erbium–Raman fiber amplifier in one branch and Raman fiber amplifier in the second branch. Multiple Raman pump units with a maximum power of 800 mW (250 mW of 1410 nm, 225 mW of 1480 nm, and 325 mW of 1495 nm) are utilized. Pump recycling technique is applied to achieve acceptable pumping efficiency. A maximum flatness gain bandwidth of 80 nm (1525–1605 nm) and average gain level of 22.5 dB are obtained at a small input signal power of -25 dBm and optimum pump power values. By comparison, a wider flatness gain of 90 nm (1520–1610 nm) and average gain level of 11.5 dB are achieved at a large input signal power of -5 dBm.

Realizing UWB Antenna Array with Dual and Wide Rejection Bands Using Metamaterial and Electromagnetic Bandgaps Techniques

This research article describes a technique for realizing wideband dual notched functionality in an ultra-wideband (UWB) antenna array based on metamaterial and electromagnetic bandgap (EBG) techniques. For comparison purposes, a reference antenna array was initially designed comprising hexagonal patches that are interconnected to each other. The array was fabricated on standard FR-4 substrate with thickness of 0.8 mm. The reference antenna exhibited an average gain of 1.5 dBi across 5.25–10.1 GHz. To improve the array’s impedance bandwidth for application in UWB systems metamaterial (MTM) characteristics were applied it. This involved embedding hexagonal slots in patch and shorting the patch to the ground-plane with metallic via. This essentially transformed the antenna to a composite right/left-handed structure that behaved like series left-handed capacitance and shunt left-handed inductance. The proposed MTM antenna array now operated over a much wider frequency range (2–12 GHz) with average gain of 5 dBi. Notched band functionality was incorporated in the proposed array to eliminate unwanted interference signals from other wireless communications systems that coexist inside the UWB spectrum. This was achieved by introducing electromagnetic bandgap in the array by etching circular slots on the ground-plane that are aligned underneath each patch and interconnecting microstrip-line in the array. The proposed techniques had no effect on the dimensions of the antenna array (20 mm × 20 mm × 0.87 mm). The results presented confirm dual-band rejection at the wireless local area network (WLAN) band (5.15–5.825 GHz) and X-band satellite downlink communication band (7.10–7.76 GHz). Compared to other dual notched band designs previously published the footprint of the proposed technique is smaller and its rejection notches completely cover the bandwidth of interfering signals.