Antenna Design: Micro Strip Patch for Spectrum Utilization in Cognitive Radio Networks

Recent wireless communication systems require antennas with lightweight and low profile. Conventional MPA suffer from narrow bandwidth owing to the fact that its unique resonance radiation is characteristically found to be less than 5%. Among the most other common ways, adopting some slots in patch radiators can tend to capitulate added controllable resonances for the purpose of bandwidth enhancement [1]. A CP was created close to the feed tip of the radiating patch. In this design, compact size and bandwidth enhancement were achieved concurrently. However, the radiation pattern had been affected by some degrees. Considering a case in point, a MPA designed with a gap coupled-sect oral patch shows an increase of bandwidth from 1.6% to 12.3%. In this proposed work, an antenna with a multilayered structure is utilized for the purpose of enriching impedance bandwidth. Although, multilayer dielectrics and patches can achieve an enhanced impedance bandwidth of over 20%, increases performance and cost of design. Bandwidth enhancement of MPA is done by ANSYS HFSS (High-Frequency Structure Simulator) Simulation Suite 14. For integrating electronic components with antenna, ANSYS structural tool HFSS is used. It provides a powerful physical analysis of antenna electronic component, ensuring their structural and thermal reliability. It boosts component performance. The MPA having Fractal length is structured on Koch curve geometry [2]. It operates in a wideband frequency range and it is based on 2.444 GHz hence giving a bandwidth of 85% and exhibit Omni-directional radiation behaviour. The measured bandwidth underpins the prerequisites of numerous bands such as WIFI 802.11y (24 GHz), Worldwide Interoperability for Microwave Access (WiMAX) (3.436 GHz, 3.742 GHz) WLAN 802.11y (3.637 GHz). A reconfigurable antenna is mostly used in CRA for spectrum utilization, it is applicable for reconfigurable multiple input multiple-output (MIMO) antennas [3‐5]. Here, micro strip patch feed’s method is used to design antennas, shorting via are used to offer bandwidth, to reduce patch size [6].This paper started with antenna research in an assortment of guidelines like fractal shaped antenna rudiments. Normally, antenna works under various frequency bands but for special application diverse antenna is needed. However, it creates a problem with positioning, partial space. To overcome this, multiband antenna is utilized. This antenna is designed by ANSYS HFSS. In Ultra Wide Band (UWB) mode, antenna is capable of covering spectrum ranges from 1 to 4 GHz, while it gets frequency re-configurability over a wide range from 0.9 to 2.6 GHz [7‐10].

This paper presents design of antenna for SU in CRN. The rest of this paper is organized as follows. In Sect. 2, design considerations is explained, also proposed algorithms for solving networks issue has been discussed, Sect. 3 presents antenna fabrication, Sect. 4 gives simulation experiment results. Section 5 explains result discussions. Finally, conclusions with future enhancement are given in Sect. 6.

The design of antenna in CRN with circular patch has been established to improve bandwidth enhancement to attain better efficiency Fig. 1 shows top view of PA with dimensions, A rectangular patch of size 66.6 mm × 128 mm is designed with a circular patch of 33.4 mm, fractal size of 28.5 mm × 3 mm. Figure 2 shows side view of patch with thickness 1.6 mm.

Figure 3 shows the antenna with gap-coupled probe feed and h-slot coupled feed, Here, dielectric substrate of 0.8 mm with 50 Ω micro strip line, feed substrate of 4.4 is developed. A H-Slot is placed over the dielectric with dimensions H1, H2 (0.5 mm, 1 mm), The flame resistant 4 (FR4) is utilized as dielectric substrate which connects circuit with antenna through line feeding technique ensuring power supply across antenna circuit. Here, H-Slot act as feed antenna, Circular patch act as secondary antenna where feed is given through ports 1,2.

Table 1 gives various dimensions for different parameters. With FR4 dielectric substrate, transmission line, quarter wave portion, rectangular patch dimension, proposed antenna design parameters are discussed with dimensions.

Figure 4 shows how PA is used in network model to attain high efficiency in CRN. A wide band signal is filtered by tuneable filter (TF) and output of TF will be a low amplification with no noise so power amplifier is used to amplify output of TF. The amplified signal is transmitted over longer distance, therefore there is a chance of having interference. In order to reduce that, low pass filter (LPF) is used. Analog to digital converter (ADC) helps to send signal in digitized form to media access control (MAC).

The physical layer acts as a bridge between output of LPF and MAC. Furthermore, layers like application, network, transport are used to remove many attack from various sources. If error is occurred during transmission it should be rectified through reconfiguration and corresponding output is measured with highly saved energy through spectrum utilization. The PA is developed on FR4 substrate and this work utilizes micro strip feed technique. The metallization region of circular structure acts as coplanar ground plane for antenna. Thus both circular and rectangular structures are integrated in some degree of space in the identical substrate with better isolation. The dimension of CP is etched in radiating patch to incorporate with a secondary antenna which has been optimized using simulation software ANSYS HFSS [11]. Figure 5 shows KF antenna in which multiple parasitic patches are attached around CP for Omni directional radiation, bandwidth enhancement.

In Fig. 6 the radiation pattern at frequency 2.4 GHz is measured and corresponding values of theta is 0.0000, angle 0.0000, magnitude 2.6050, From curve, it is clear that setup is about to sweep in first condition the phi value becomes 0°, In second condition phi value becomes 90degree which ensures horizontal polarization which leads to better performance over network An antenna that is based on KF geometry with micro strip line feeding technique used for wideband wireless application is explained.

Due to additional loading effect of parasitic strips which helps to energize through micro strip line feeding, the variation affects resonance in low band and dimensions can alter the size of micro strip line which is used to fine-tune input impedance [12, 13]. The Koch curve arrangement is applied to upper bottom, left and right side of a rectangular patch. The impedance bandwidth of proposed model is 85% from 2.4444 GHz (2:1 VSWR). A gap feed slotted patch was established in [14]. In [15], a wide-scanning phase array was offered with a bandwidth of 51%, scanning range up to 60°. In [16], L-shaped feed were engaged to stimulate wideband antenna arrays was utilized to get high gain.

Following underlie spectrum sharing system, transmit power at PT is sternly inhibited in [17, 18], the transmit power is calculated using Eq. 1, it is given byP_T—transmit power, P_I is maximum endurable intrusion power, \(R_{Y}\)—Channel loss coefficient, P_max—Maximum power.

The Antenna Selection System (ASS) is important because it has been designed to extend CRN performance [19], and outage power is represented by Eqs. 2 and 3 given bywhere S_c is goal confidentiality charge andwhere D_C and E_C indicates the capability of major and eavesdropper’s channels.

The design gives comparison of two return losses output for rectangular and circular ground plane and radiation patterns at various frequency level is measured and it is shown in Figs. 6 and 7.

In Fig. 7 radiation pattern at frequency 3.56 GHz is measured and corresponding calculated values are theta 1.0000, angle 1.0000, magnitude 2.3848. The first output sample is taken from radiation pattern at 2.4 GHz which gives higher efficiency 95.7% than radiation pattern at 3.96 GHz. The use of circular ground plane plays very important task for receiving high impedance bandwidth [20].

By using 3D modeler, coordinate system (X-Axis, Y-Axis, Z-Axis) is formed. Initially measure data is taken by reference position as (0, 0, 0) mm, current position as (0, 0, 0) mm with distance (X, Y, Z) 0 mm.

Next a substrate is created by positioning the reference as mentioned, current position is modified as (2.4, 2.4, 0) mm with distance (3.304:125,497) mm as shown in Fig. 9. To create an angle point 1, point 2 is set at o degree, The reference position is marked as (2.4, 2.2, 0) mm similarly current position remains same, distance (X, Y, Z) is 0 mm.

Subsequently to create a solid vacuum box using global coordinate system, positioning (0.20, 0.20, 0) mm and placing X-Axis 40 mm, Y-Axis 40 mm, and Z-Axis 0.5 mm whereas the evaluated values is calculated as 40 mm, 40 mm, 0.2 mm. Now a rectangular dielectric base is created, The cylinder is created by placing entire point as (0, 0, 0) mm along Z-Axis with radius 1 mm and height 1 mm. Next to create feed centre point is modified as (14, − 36, 0) mm with radius 2 mm and height 20 mm, Then inner portion of feed cylinder was formed using centre point (14, − 36, 0) mm along Z-Axis with radius 0.6 mm and height 0.5 mm which is shown in Fig. 10.

To create a CP above dielectric substrate, a centre point is measured along the axis by positioning values (0, 0, 0.5) mm, radius is marked as 9 mm. The number of initial segments are zero, evaluated value of CP is calculated as 8.4852 mm. The transmission path (small rectangle portion) which is coupled with CP as shown in Fig. 11 is created by placing axis position (0, 0, 0.5)mm along Z-Axis with X-Axis 20 mm, Y-Axis 2 mm, here evaluated value of X, Y are same as mentioned. To couple patch with dielectric FR4 is used as substrate material, In this proposed CP structure H shape were imprinted with CP. This model creation can be done within HFSS using 3D modeler. The CP is considered in making micro strip patch, It can produce low return loss.

The main work is to form HFSS sculpt consisting of physical imitation. Figure 12a shows field overlays of magnetic quantities in a near and far field with in CP limit, and radiation spreads through CP in all directions when dielectric substrate is energized by cylindrical cavity.

Figure 12b shows layer formation of H field, due to magnetic flux, electricity travels through CP and convert as radiation. Figure 12c shows 3D pattern.

From Fig. 13a it is clear that, magnetic field can be illustrated by extracting from a preset magnet in 3D space. A Points in H field space can be denoted in (r, θ) polar plot formation, where r is distance, θ is angle. It is analysed that fields are associated with CP when the power is applied through transmission path, dielectric substrate is giving the best excitation to CP to produce enormous radiation through cylindrical portion as primary antenna as shown in Fig. 13b. The magnitude of magnetic field along Z direction as shown in Fig. 13c. The magnetic quantities are excited by power through cylindrical cavity.

Figure 14a shows field overlays of electric field, The moment when CP is excited, the fields inside CP are about to collide with each other due to this charge is produced inside CP and excited with radiation fields. Figure 14b shows E Field Excitation, The moment when CP is excited, the fields inside CP are about to collide with each other due to this charge is produced inside CP and excited with radiation fields. In Fig. 14c shows different E field patterns for CP.

By making far fields report, polar plot output for CP can be created and near field E is noted which is shown in Fig. 15.

The CP is adjusted in any direction in such a way that where maximum radiation is obtained. A 3D polar plot is used to find theta value, magnitudes as shown in Fig. 16a. This explains CP is created with radiation fields which can be sent/received in all directions over medium. Figure 16b shows rotational plot, by this we get CP is giving electric fields, It can be anywhere over medium.

In Fig. 17 shows H-field of an antenna which is designed by HFSS tool, A antenna is located on a center point of dielectric, by this maximum, equally distributed radiation in all directions were observed.

In Fig. 18, Red shaded portion gives maximum radiation when gain value is − 9.2678e + 000, mild red denotes minimum radiation when gain increased to − 1.0958e + 001, orange shows radiation pattern when gain is − 1.2648. The green color is segregated as several shades and those shades denote radiation pattern according to gain values which ranges from − 1.7719e + 001 to − 2.6171e + 001 similarly blue color indicates radiation pattern when gain value ranges from − 2.7861e + 001 to − 3.6312e + 001.

In Fig. 19, The gain of 2.2681e + 000 shows maximum range of radiation at red color, at yellow it shows radiation pattern with gain of − 6.6470e + 000, Green color has several shades and radiation pattern is obtained at a gain value between − 8.8757e + 000, − 2.2248e + 001. The blue color shows radiation pattern at a gain of − 2.4477e + 001 to − 3.3392e + 001. In inscribed circular fractal antenna the dimension is about 22 × 22 × 1.6 which provides an impedance bandwidth of 3.37–6.53, impedance bandwidth percentage is 63.8 finally gain, efficiency of antenna are 2.67. The next level of comparison is made by return losses output of two different ground plane and it is indicated in Figs. 20 and 21.

In Fig. 20 by using ANSYS HFSS it is observed that return losses output for various gain, frequency values. The different plot values are Gain − 10.1589 dB Vs Frequency 24,700 GHz, Gain − 36.0519 dB Vs Frequency 24,350 GHz.

In Fig. 21 return loss is slightly reduced and performance of antenna is improved for frequency value 42,427 GHz, return loss is reduced to − 9.9744 dB. and for frequency 24380 GHz, the observed return loss is − 10.266 dB.

In network when micro strip is reconfigured, the SU and throughput performance is increased gradually which is shown in Fig. 22 in which red line indicates increase in performance after using micro strip antenna and its throughput, green line shows previous throughput, and it is simulated using NS2 (Network Simulator-2).

Table 2 shows production of this work in comparison with presentation of other published 60 GHz antenna, L-shaped feed network and simulated results were calculated. The dimensions of fractal antenna is 14 × 30.4 × 1.6, it produces an impedance bandwidth of 3.31–7.84 GHz and impedance bandwidth percentage is 81.26, and corresponding gain and efficiency values are 2.58–3.66 dB, 83.2%. In modified KF antenna a dimension is set to 16 × 30.4 × 1.6 resultant impedance bandwidth is 3.31–8.24 GHz, impedance bandwidth percentage is 85.5%, resultant gain is 1.96–3.05 dB, efficiency of antenna is 87.5%. The dimension of Hybrid fractal antenna is 16 × 30.4 × 1.6 which produces an impedance bandwidth of 3.3–8.18 GHz, impedance bandwidth percentage is 85.01, gain of antenna is 1.97 to 3.4, it produces an efficiency of 86.7%.

The final version of micro strip KF antenna is developed from fractal length, circular patch. The PA has a dimension of 14 × 30.4 × 1.6 which gives an impedance bandwidth of 2.4–4.44 GHz, impedance bandwidth percentage of 85 is achieved, impedance bandwidth 2.4–4.44, Gain 2.69–4.2 dB, efficiency is 95.7% which is maximum, more reliable than LTCC Micro strip patch LTCCMP.

Initially radiation patterns were discussed at various frequency level. The measured radiation pattern of micro strip circular patch at frequency of 2.4 GHz which is suitable for SU in CRA, and fabrication model is designed by coordinate system, under measure data initial values were assigned along with substrate, feed, plane selection is selected and frequency sweep, excitation, radiation field were analyzed, corresponding 3D polar plot for near and far field reports were generated, then E-field, H-field overlays were plotted. The antenna gain with and without cone were calculated, finally return losses for circular, rectangular patches were compared, throughput improvement is taken after micro strip is used in a network.

This antenna design makes it attractive for future communication systems and especially for SU in CRN. The power allocation policies have been proposed, Koch curve fractal antenna is conceived and developed for wideband wireless applications which support an impedance bandwidth of 81.26% from 3.31 GHz. The highest peak gain of 4.4 dB is accomplished with a total efficiency of 80%. The proposed KF antenna model exhibits a tremendous increase in bandwidth showing 85.02%in the range 2.44 GHz (2:1 VSWR BW). The measured bandwidth underpins the prerequisites of several bands such as WIFI802.11y (2.4 GHz), WiMAX (3.436 GHZ, 3.742GHZ) and WLAN802.11 (5.31632 GHz), for further understanding behavior of PAs, 2D radiation patterns, 3D polar plot were represented.