On-body antenna wit parasitic elements

An antenna with multi-elements that act together to form an array is required to increase the gain. One example is the well-known Yagi-Uda antenna. Such an antenna is widely used for television communication in which it operates at high frequency (HF), very high frequency (VHF) and ultra high frequency (UHF). It consists of a driven element and a number of parasitic radiators in which currents are induced by mutual coupling. Some applications consider the mutual coupling effect undesirable because it degrades the performance. However, in the parasiticaray it is central to the operation. The parasite elements are useful to increase the gain, create a directional beam and enhance the bandwidth impedance of the antenna

5G Fixed Beam Switching on Microstrip Patch Antenna

5G technology is using millimeter-wave band to improve the wireless communication system.  However, narrow transmitter and receiver beams have caused the beam coverage area to be limited. Due to propagation limitations of mm wave band, beam forming technology with multi-beam based communication system, has been focused to overcome the problem. In this letter, a fixed beam switching method is introduced. By changing the switches, four different configurations of patch array antennas are designed to investigate their performances in terms of radiation patterns, beam forming angle, gain, half-power bandwidth and impedance bandwidth at 28 GHz operating frequency for 5G application. Mircostrip antenna is preferred due to its low profile, easy in feeding and array configurations. Three different beam directions had been formed at -15°, 0°, and 15° with half-power bandwidth of range 45˚ to 50˚

Radiation pattern performance of unequally linear arrays with parasitic element

For next generation of 5G mobile base station antennas, multibeam, multifrequency and low sidelobe characteristics requested. Simplify the feeding network will contribute a low feeder loss and frequency dependent. From the previous research by the author, low sidelobe level reported by density tapered array configuration from -13 dB to -16 dB and the result maintained for wideband operation frequency at 28 GHz, 42 GHz, and 56 GHz. However, the grating lobe has occurred due to element spacing larger than a wavelength of higher frequency (56 GHz). In this paper, an investigation was made of the performance of radiation pattern for unequally microstrip linear array antenna in frequency 42 GHz and 56 GHz by loading parasitic elements. The effect of parasitic element to the impedance, gain, and sidelobe level of unequally microstrip linear spaced tapered array also examined. The design has been simulated using Ansoft High Frequency Structural Simulator (HFSS) ver 16.0

Mutual coupling reduction and pattern error correction in a 5g beamforming linear array using CSRR

A four-element printed antenna array operating at 25-GHz frequency with complementary split ring resonator (CSRR) has been proposed for beamforming applications. The CSRR elements have been used to suppress the mutual coupling in the proposed array. The existence of the CSRR configuration in antenna array controls the unnecessary surface current flow between the array elements, and thus the mutual coupling between array elements has been significantly reduced up to -55 dB. The effect of mutual coupling on the array radiation patterns has been studied in the presence and absence of CSRRs. The effectiveness of the CSRR has been studied by steering the main beam as well as the nulls in different angles. By implementing the CSRR elements in array antenna, the distorted array patterns have been recovered and are presented. The proposed antenna array with the CSRR has the advantage of easy and low-cost fabrication and it offers excellent coupling suppression without changing the antenna profile. The commercially available simulation tools such as MATLAB and Ansys HFSS have been used for array weights calculation and antenna design respectively. Finally, the fabricated prototype has been experimentally verified, and it shows that the analytical and computed results agree well with the measured results

Miniaturize size of dual band branch-line coupler by implementing reduced series arm of coupler with stub loaded

An extremely reduced size branch-line coupler operating at dual frequencies of WLAN band 2.45 GHz and 5.8 GHz is presented which is 58% smaller compared to the conventional design. The technique presented introduces the combination method in which the length of series lines is half than the length of shunt branch lines and the loading of stub tapped to the center of the series branch line that forms the couplers arms. Furthermore, the coupler accurately divides the input signal by two parts with the same power and 90° phase difference. Also, the reflection coefficient and the isolation are as good as conventional one. The agreement of the measurement and simulated confirms the theory and validates the proposed coupler design. The measurement shows 33.83% and 9.22% bandwidth for the lower and upper frequency, respectively

Complementary split ring resonator for isolation enhancement in 5G communication antenna array

A square-shaped complementary split ring resonator (CSRR) filtering structure for isolation improvement is presented in this paper. The proposed research work investigates the design and development of a simple and compact CSRR structure. In order to verify the performance of the proposed filtering element and improve the isolation among the closely placed antenna elements, arrays of configured CSRR structures are implemented between two antenna elements. An array of configured CSRR elements has been integrated with the printed antenna on the top and bottom layers. The proposed filtering elements offer an enhancement in isolation by 25 dB as compared to the simple array. The entire configuration has been simulated using the Ansoft HFSS simulator. Finally, the proposed design is fabricated and experimentally validated. In the experiment, coupling suppression of -51 dB at the operating frequency is successfully achieved, resulting in a recovery of the array pattern. The proposed antenna is highly efficient, which is suitable to be utilized for 5G communication

Ultra wideband printed monopole antenna with dual-band circular polarization

An ultra wideband printed monopole antenna with dual band circular polarization for wireless application is presented. The antenna dimensions are 30 × 30 × 1.6 mm3. The proposed antenna is able to cover frequency range between 2.65 GHz and 11 GHz with impedance bandwidth is around 122%. With the use of I-shape slit in the radiation element and the T-slot in the ground plane, the ultra wideband and circular polarization are excited. In addition, the rectangular slit is added in the ground plane, to enhance the impedance- and Axial Ratio - bandwidth. Furthermore, the dual band circular polarization with right hand circular polarization at 3.1 GHz and the left hand circular polarization at 7 GHz are obtained. Also, the 3-dB axial ratio bandwidths are about 242 and 246 MHZ at the lower and upper band without rectangular slit and 356 and 546 MHZ at the lower and upper band with rectangular slit, respectively

Dielectric Resonator Reflectarray Antenna Unit Cells for 5G Applications

This paper presents an investigation for the performance comparison of three different unit cell configurations operating at 26 GHz for 5G applications. The unit cells are cross shape dielectric resonator, cross microstrip patch and cross hybrid dielectric resonator. Verification of the comparison has been done by simulations using commercial Computer Simulation Technology Microwave Studio (CST MWS). The simulated results for reflection phase, slope variation, reflection loss and 10% bandwidth were analyzed and compared. The results indicate that the optimum configuration to be deployed for the reflectarray’s unit element in order to fulfill the 5G requirements of a wide bandwidth is the cross hybrid DRA. This configuration is a combination of cross DRA with cross microstrip patch as the parasitic element in order to tune the phase and provide a wide phase range with smooth variation slope. Cross hybrid DRA provided a wide phase range of 520° with 0.77 dB loss and 10% bandwidth of 160 MHz

Rectangular dielectric resonator antenna array for 28 GHz applications

In this paper, a Rectangular Dielectric Resonator Antenna (RDRA) with a modified feeding line is designed and investigated at 28 GHz. The modified feed line is designed to excite the DR with relative permittivity of 10 which contributes to a wide bandwidth operation. The proposed single RDRA has been fabricated and mounted on a RT/Duroid 5880 (εr = 2.2 and tanδ = 0.0009) substrate. The optimized single element has been applied to array structure to improve the gain and achieve the required gain performance. The radiation pattern, impedance bandwidth and gain are simulated and measured accordingly. The number of elements and element spacing are studied for an optimum performance. The proposed antenna obtains a reflection coefficient response from 27.0 GHz to 29.1 GHz which cover the desired frequency band. This makes the proposed antenna achieve 2.1 GHz impedance bandwidth and gain of 12.1 dB. Thus, it has potential for millimeter wave and 5G application

Bio-inspired robotic locomotion model: Response towards food gradient changes and temperature variation

The nervous system is a complex yet efficient structure - with superior information processing capabilities that surely surpass any man-made high-performance computer. Understanding this technology and utilising it in robotic navigation applications is essential to understand its underlying mechanism. One of the approaches is using a nematode’s biological network model, as having a simple network structure while holding a complex locomotion behaviour. For instance, its ability to navigate via local concentration cue (chemotaxis) and the ability to dynamically respond towards surrounding temperature (thermotaxis). To date, the simulation of currently available models is on static environment conditions and the nematode’s movement decision is based on the deterministic non-linear response towards gradient changes. Commonly, parameters of these models were optimised based on static conditions and require adjustment if simulated within a dynamic environment. Therefore, this work proposed a new nematode’s biological locomotion model where the movement trajectory is determined by the probability of “Run” and “Turn” signals. The model is simulated within a 2D virtual environment with complex concentration gradient and variants of temperature distribution. The analysis result shows the nematode’s movement of the proposed model agreed with the finding from experimental studies. Later, the proposed model in this work will be employed to develop a biological inspired multi-sensory robotic system for navigating within a dynamic and complex environmen