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  • Several slot radiators in a waveguide form a group antenna. The waveguide is used as the transmission line to feed the elements. In order for radiate in the correct phase, all single slots must be cutted in the distance of the wavelength, that is valid for the interior of the waveguide. This wavelength differs from the wavelength.

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  1. To increase the gain, four L-shaped slots are etched in the ground plane. The measured results show that the proposed structure retains a wide impedance bandwidth of %, which is 20% better than the reference antenna. The average gain is also increased, which is about dBi with a stable.:
    angular microstrip antenna [1]. From our experimental point of view, we choose feed point fixed at P(−, −), with varying slot section positions in horizontal direction. We have used two popular slot shapes for the evaluation of antenna character- istics, a triangular slot (Δ) and a V type (non-tapered) slot. Triangular slots. Abstract—The dual-frequency properties of a dual annular-ring slot antenna fed by coplanar waveguide (CPW) and microstrip feedline are presented and experimentally studied. The proposed antenna is con- structed by dual concentric annular-ring slots fabricated on FR4 sub- strate with single feed. The proposed slot. Abstract: Two novel designs of planar elliptical slot antennas are presented. Printed on a dielectric substrate and fed by either microstrip line or coplanar waveguide with U-shaped tuning stub, the elliptical/circular slots have been demonstrated to exhibit an ultrawideband characteristic. The performances and characteristics.
  2. The antenna is built using ridge gap waveguide technology, formed between two parallel metal plates without the requirements of electrical contact between these plates. The corporate-feed network is realized by a texture of pins and a guiding ridge in the bottom plate, and the radiating slots are placed in the smooth top.:
    from the antenna array, which will be fed by slots in the ground plane and thus will be realized. Afterwards CPW line is connected to the slot-antenna feed point and the wide CPW line is connected to the coaxial SMA com). DOI /mop Key words: slot antenna; coplanar waveguide feed; tapered transition. half-wavelength capacitively-coupled slot antenna, in contrast to the standard one-wavelength CPW-fed slot antenna (Fig. 1). The generalized CPW open-end structure can be considered as a slotline resonator shorted at two ends and fed symmetrically on its length by the two slots of the CPW feed line. This rectangular slot. A slot antenna consists of a metal surface, usually a flat plate, with one or more holes or slots cut out. When the plate is driven as an antenna by a driving frequency, the slot radiates electromagnetic waves in a way similar to a dipole antenna. The shape and size of the slot, as well as the driving frequency, determine the.
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The impedance bandwidth changes significantly for variation of Lf because of the sensitivity of the impedance matching to this parameter. However, with the decrease in the length of Lf , the upper resonance shifts upward and impedance bandwidth decreases. With the length of Lf chosen to be The width of the strip line has a minor effect on the lower resonant mode but a large effect on the upper resonant mode, as shown in Figure 7. It can be clearly seen that there is a minor effect in the reflection coefficient but a major improvement in terms of gain.

The insertion of L -shaped slots in the ground plane created some sort of discontinuity which caused the electric current launched by the primary radiator to reroute its path along the conducting surface of the ground.

As a result, the electrical length of the ground is increased. With the strong coupling from the radiator, the ground slots cause a considerable impact on the input impedance. This positive coupling effect is responsible for increasing gain. Figure 10 shows the axial ratio of the proposed antenna. Generally, the axial ratio is considered to determine antenna polarization. At the six resonant frequencies of 3. It can be understood that the axial ratio decreases with higher frequency due to the low current intensity in the upper side of the patch and opposite direction.

The input impedance and the voltage standing wave ratio are validated in the Smith chart shown in Figure Three of the resonances are in the 2: The Rx values in the Smith chart table represent the input impedance. The curve has a tight resonant loop close to the centre of the Smith chart. This means that the proposed antenna greatly enhances the impedance bandwidth.

The markers m1 and m2 represent the start and ending frequencies of the operating band. Figure 12 shows the surface current distribution of the radiating patch element of the proposed antenna at 3. It has been observed that at the lower band the current intensity is much weaker. The current is more exciting in strip line and wide slotted diagonal points. Specially, the left and right arms of wide slot are more excited. Besides, L slots in ground plane are also more excited than plane area.

Therefore, from the relationship between gain, power and current of the proposed antenna can be validated from the current distribution. Figure 13 shows the radiation efficiency of the proposed antenna.

It can be seen that The radiation efficiency at the lower resonant frequencies of 3. On the other hand, at the upper resonant frequencies of 5. The performance of the proposed antenna was analysed and optimized using a FEM-based high-frequency 3D full-wave electromagnetic simulator, Ansoft's HFSS, and plotted using the scientific graphing and data analysis software OriginPro and Excel.

The results of the proposed antenna prototype were measured in a rectangular-shaped 5. A double ridge guide horn antenna was used as a reference antenna.

A turn table with a diameter of 1. Figure 14 shows a photograph of the proposed antenna prototype. Figure 15 shows the simulated and measured return loss of the optimized proposed antenna.

A slight discrepancy occurred, which led to the differences between simulated and measured return loss value due to the effect from soldering of the SMA Sub Miniature Version A connector and the loss from the connecting cable. The results show that the antenna provides a very wide impedance bandwidth of over Detailed numerical and experimental investigations confirm that the achieved impedance bandwidth is limited by the impedance match between the microstrip line height and width, the rotated square slot diagonal points with respect to feed, and the wide square slot arm's length.

Figure 16 shows the measured gain of the proposed antenna. The highest peak gain of the proposed antenna is 4. The average peak gain of the proposed antenna is 4. Figure 17 shows the measured E XZ -H YZ plane normalized radiation pattern of the proposed antenna prototype at different frequencies.

It can be undoubtedly seen that good omnidirectional characteristics are obtained for the proposed antenna excited at all other frequencies across the operating band. Furthermore, the effect of cross-polarization is much smaller than the copolarization desired. Although at higher frequencies, more harmonics are observed mainly in the cross-polarization radiation field, the antenna has a good stable radiation without gain degradation. Table 3 compares the proposed and some existing antennas.

The table shows that the proposed antenna achieves wider bandwidth and higher gain with smaller size compared with the reported antennas, although some of the reported antennas obtain a wide bandwidth and higher gain compromising the overall size and structure.

By introducing rotated square slot diagonal points in the middle of the strip line, the impedance bandwidth of the proposed wide-slot antenna can be significantly enhanced.

In addition, the size of the proposed antenna can be reduced. Moreover, the four L -shaped slots are embedded in the ground to increase the gain of the antenna. The proposed structure reveals an average peak gain of 4. By properly choosing the suitable slot shape position and tuning their dimensions parameter with simulation software, the proposed design with wide operating bandwidth, relative small size, peak gain, and improved radiation pattern is obtained.

The authors declare that there is no conflict of interests regarding the publication of this paper. National Center for Biotechnology Information , U. Journal List ScientificWorldJournal v. Published online Feb Mandeep , and N. Received Dec 13; Accepted Jan 6.

This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This article has been cited by other articles in PMC. Abstract This paper presents a printed wide-slot antenna design and prototyping on available low-cost polymer resin composite material fed by a microstrip line with a rotated square slot for bandwidth enhancement and defected ground structure for gain enhancement.

Introduction In modern wireless communication systems, the demand for wide and multiband antennas is increasing to support multiusers and to provide more information with higher data transmitting and receiving rates.

Antenna Design Architecture The geometry of the proposed wide-slot defected ground structure antenna is portrayed in Figure 1.

Surface current distribution of the proposed antenna at a 3. Experimental Verification The performance of the proposed antenna was analysed and optimized using a FEM-based high-frequency 3D full-wave electromagnetic simulator, Ansoft's HFSS, and plotted using the scientific graphing and data analysis software OriginPro and Excel. Comparison between simulated and measured reflection coefficient of the proposed antenna. Radiation pattern of the proposed antenna at a 3.

Conflict of Interests The authors declare that there is no conflict of interests regarding the publication of this paper. Development of an antenna material based on rubber that has flexibility and high impact resistance. Analyzing advances in antenna Materials. Antenna SyStems and Technology. Ceramic-polytetrafluoroethylene composite material-based miniaturized split-ring patch antenna. Science and Engineering of Composite Materials.

Miniaturized modified circular patch monopole antenna on ceramic-polytetrafluroethylene composite material substrate. Journal of Computational Electronics. Assis RRd, Bianchi I. Analysis of microstrip antennas on carbon fiber composite material.

Journal of Microwaves, Optoelectronics and Electromagnetic Applications. Parametric analysis of a glass-micro fibre-reinforced PTFE material, multiband, patch-structure antenna for satellite applications. Optoelectronics and Advanced Materials.

A compact square loop patch antenna on high dielectric ceramic—PTFE composite material. Investigations on ultrawideband pentagon shape microstrip slot antenna for wireless communications.

A new double L-shaped multiband patch antenna on a polymer resin material substrate. Circular slot with a novel circular microstrip open ended microstrip feed for UWB applications. Progress in Electromagnetics Research. Experimental studies of printed wide-slot antenna for wide-band applications. The Scientific World Journal.

Wideband compact antenna with partially radiating coplanar ground plane. Applied Computational Electromagnetics Society Newsletter.

Printed planar antenna for wideband applications. Journal of Infrared, Millimeter, and Terahertz Waves. Bandwidth enhancement of a microstrip-line-fed printed wide-slot antenna. Dissanayake T, Esselle KP. UWB performance of compact L-shaped wide slot antennas. Bandwidth enhancement of a microstrip line-fed printed wide-slot antenna with a parasitic center patch.

Bandwidth enhancement of a microstrip-line-fed printed wide-slot antenna with a fractal-shaped slot. Compact wideband Koch fractal printed slot antenna.

This slot behaves according to Babinet's principle as resonant radiator. Jacques Babinet - was a French physicist and mathematician, formulated the theorem that similar diffraction patterns are produced by two complementary screens Babinet's principle. This principle relates the radiated fields and impedance of an aperture or slot antenna to that of the field of a dipole antenna.

The polarization of a slot antenna is linear. The impedance of the slot antenna Z s is related to the impedance of its complementary dipole antenna Z d by the relation:. The band width of a narrow rectangular slot is equal to that of the related dipole, and is equal to half the bandwidth of a cylindrical dipole with a diameter equal to the slot width.

Although the theory requires an infinite spread conductive surface, the deviation from the theoretical value is small when the surface is greater than the square of the wavelength. The feeding of the slot antenna can be done with ordinary two-wire line. The impedance is dependent on the feeding point, as in a dipole. A shift of the feed point from the center to the edge steadily decreases the impedance. The application of slot antennas can be versatile.

They can replace dipoles e. If a dipole is used for feeding of a parabolic antenna to generate a vertically orientated but horizontally polarized fan beam , then this dipole must be orientated horizontally. This would mean that the edge surfaces of the parabolic reflector will not be sufficiently illuminated, but a lot of energy above and below the reflector would be lost. In addition, the length of the dipole is extended in a plane, in which is demanding a point like source of radiation for the focus of the parabolic reflector.

If this dipole is replaced by a slot antenna, in this case don't appear these disadvantages. Slot antennas in waveguides provide an economical way of the design of antenna arrays. The position, shape and orientation of the slots will determine how or if they radiate.

If slots are cut into the walls, so the current flow is affected more or less depending on the location of the slot. If the slots are sufficiently narrow so the slots B and C Fig. These two slots radiate not or very little. The slots A and D represent barriers to the current flow. Thus, this current flow acts as an excitation system for the slot, this one acts as radiator. Since the wave in the waveguide moves forward, these drawn lines migrate in the direction of propagation.

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It can be seen that resonance frequencies are shifted upward when L 1 increases and downward when L 1 increases. An important feature of the proposed antenna design is the stimulus of impedance matching caused by the coupling effects between wide slot and feed length and width. The other parameter remains unchanged as in Table 1. Due to the variety of Lf , both lower and upper resonances have large changes.

This is because increasing the length of Lf significantly increases the total capacitive effect and thus lowers the lowest resonance frequency while decreasing the operating band.

The impedance bandwidth changes significantly for variation of Lf because of the sensitivity of the impedance matching to this parameter. However, with the decrease in the length of Lf , the upper resonance shifts upward and impedance bandwidth decreases. With the length of Lf chosen to be The width of the strip line has a minor effect on the lower resonant mode but a large effect on the upper resonant mode, as shown in Figure 7.

It can be clearly seen that there is a minor effect in the reflection coefficient but a major improvement in terms of gain. The insertion of L -shaped slots in the ground plane created some sort of discontinuity which caused the electric current launched by the primary radiator to reroute its path along the conducting surface of the ground.

As a result, the electrical length of the ground is increased. With the strong coupling from the radiator, the ground slots cause a considerable impact on the input impedance. This positive coupling effect is responsible for increasing gain. Figure 10 shows the axial ratio of the proposed antenna. Generally, the axial ratio is considered to determine antenna polarization.

At the six resonant frequencies of 3. It can be understood that the axial ratio decreases with higher frequency due to the low current intensity in the upper side of the patch and opposite direction. The input impedance and the voltage standing wave ratio are validated in the Smith chart shown in Figure Three of the resonances are in the 2: The Rx values in the Smith chart table represent the input impedance. The curve has a tight resonant loop close to the centre of the Smith chart. This means that the proposed antenna greatly enhances the impedance bandwidth.

The markers m1 and m2 represent the start and ending frequencies of the operating band. Figure 12 shows the surface current distribution of the radiating patch element of the proposed antenna at 3.

It has been observed that at the lower band the current intensity is much weaker. The current is more exciting in strip line and wide slotted diagonal points. Specially, the left and right arms of wide slot are more excited. Besides, L slots in ground plane are also more excited than plane area. Therefore, from the relationship between gain, power and current of the proposed antenna can be validated from the current distribution. Figure 13 shows the radiation efficiency of the proposed antenna.

It can be seen that The radiation efficiency at the lower resonant frequencies of 3. On the other hand, at the upper resonant frequencies of 5. The performance of the proposed antenna was analysed and optimized using a FEM-based high-frequency 3D full-wave electromagnetic simulator, Ansoft's HFSS, and plotted using the scientific graphing and data analysis software OriginPro and Excel. The results of the proposed antenna prototype were measured in a rectangular-shaped 5.

A double ridge guide horn antenna was used as a reference antenna. A turn table with a diameter of 1. Figure 14 shows a photograph of the proposed antenna prototype. Figure 15 shows the simulated and measured return loss of the optimized proposed antenna.

A slight discrepancy occurred, which led to the differences between simulated and measured return loss value due to the effect from soldering of the SMA Sub Miniature Version A connector and the loss from the connecting cable.

The results show that the antenna provides a very wide impedance bandwidth of over Detailed numerical and experimental investigations confirm that the achieved impedance bandwidth is limited by the impedance match between the microstrip line height and width, the rotated square slot diagonal points with respect to feed, and the wide square slot arm's length. Figure 16 shows the measured gain of the proposed antenna. The highest peak gain of the proposed antenna is 4.

The average peak gain of the proposed antenna is 4. Figure 17 shows the measured E XZ -H YZ plane normalized radiation pattern of the proposed antenna prototype at different frequencies. It can be undoubtedly seen that good omnidirectional characteristics are obtained for the proposed antenna excited at all other frequencies across the operating band. Furthermore, the effect of cross-polarization is much smaller than the copolarization desired.

Although at higher frequencies, more harmonics are observed mainly in the cross-polarization radiation field, the antenna has a good stable radiation without gain degradation.

Table 3 compares the proposed and some existing antennas. The table shows that the proposed antenna achieves wider bandwidth and higher gain with smaller size compared with the reported antennas, although some of the reported antennas obtain a wide bandwidth and higher gain compromising the overall size and structure.

By introducing rotated square slot diagonal points in the middle of the strip line, the impedance bandwidth of the proposed wide-slot antenna can be significantly enhanced. In addition, the size of the proposed antenna can be reduced. Moreover, the four L -shaped slots are embedded in the ground to increase the gain of the antenna. The proposed structure reveals an average peak gain of 4. By properly choosing the suitable slot shape position and tuning their dimensions parameter with simulation software, the proposed design with wide operating bandwidth, relative small size, peak gain, and improved radiation pattern is obtained.

The authors declare that there is no conflict of interests regarding the publication of this paper. National Center for Biotechnology Information , U. Journal List ScientificWorldJournal v. Published online Feb Mandeep , and N. Received Dec 13; Accepted Jan 6. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

This article has been cited by other articles in PMC. Abstract This paper presents a printed wide-slot antenna design and prototyping on available low-cost polymer resin composite material fed by a microstrip line with a rotated square slot for bandwidth enhancement and defected ground structure for gain enhancement. Introduction In modern wireless communication systems, the demand for wide and multiband antennas is increasing to support multiusers and to provide more information with higher data transmitting and receiving rates.

Antenna Design Architecture The geometry of the proposed wide-slot defected ground structure antenna is portrayed in Figure 1. Surface current distribution of the proposed antenna at a 3. Experimental Verification The performance of the proposed antenna was analysed and optimized using a FEM-based high-frequency 3D full-wave electromagnetic simulator, Ansoft's HFSS, and plotted using the scientific graphing and data analysis software OriginPro and Excel.

Comparison between simulated and measured reflection coefficient of the proposed antenna. Radiation pattern of the proposed antenna at a 3. Conflict of Interests The authors declare that there is no conflict of interests regarding the publication of this paper. Development of an antenna material based on rubber that has flexibility and high impact resistance. Analyzing advances in antenna Materials. Antenna SyStems and Technology. Ceramic-polytetrafluoroethylene composite material-based miniaturized split-ring patch antenna.

Science and Engineering of Composite Materials. Miniaturized modified circular patch monopole antenna on ceramic-polytetrafluroethylene composite material substrate. Journal of Computational Electronics. Assis RRd, Bianchi I. Analysis of microstrip antennas on carbon fiber composite material. Journal of Microwaves, Optoelectronics and Electromagnetic Applications.

Parametric analysis of a glass-micro fibre-reinforced PTFE material, multiband, patch-structure antenna for satellite applications. Optoelectronics and Advanced Materials. A compact square loop patch antenna on high dielectric ceramic—PTFE composite material. Investigations on ultrawideband pentagon shape microstrip slot antenna for wireless communications.

A new double L-shaped multiband patch antenna on a polymer resin material substrate. Circular slot with a novel circular microstrip open ended microstrip feed for UWB applications. Progress in Electromagnetics Research. Experimental studies of printed wide-slot antenna for wide-band applications. The Scientific World Journal. Wideband compact antenna with partially radiating coplanar ground plane.

Applied Computational Electromagnetics Society Newsletter. Printed planar antenna for wideband applications. Journal of Infrared, Millimeter, and Terahertz Waves. Bandwidth enhancement of a microstrip-line-fed printed wide-slot antenna. If the slots are sufficiently narrow so the slots B and C Fig. These two slots radiate not or very little. The slots A and D represent barriers to the current flow. Thus, this current flow acts as an excitation system for the slot, this one acts as radiator.

Since the wave in the waveguide moves forward, these drawn lines migrate in the direction of propagation. The slot gets one always alternating voltage potential at its slot edges depending on the frequency in the waveguide. The power that the slot radiates can be altered by moving the slots closer or farther from the edge. In order to reduce this coupling, for example the slot A could be moved closer to one of the shorter waveguide walls. Rotating of the slots would have a the same effect an angle between the orientations of A and B or C and D.

Basic geometry of a slotted waveguide antenna The slot radiators are on the wider wall of the rectangular waveguide. Several slot radiators in a waveguide form a group antenna. The waveguide is used as the transmission line to feed the elements. In order for radiate in the correct phase, all single slots must be cutted in the distance of the wavelength, that is valid for the interior of the waveguide. This wavelength differs from the wavelength in free space and is a function of the wider side a of a rectangular waveguide.

Basic geometry of a slotted waveguide antenna with rotated slot antennas on the narrower wall. The wavelength within the waveguide is longer than in free space. The number and the size of the side lobes is affected so unfavorably. The slots are often attached to the left and right eccentrically with reduced coupling. If mounted on the narrow side of the waveguide, it may happen that the length for the resonant slot radiator is shorter than the wall.

In this case, the slot can be also guided around the corners, it then lies also slightly on the A-side of the waveguide. In practice, these slots are all covered with a thin insulating material for the protection of the interior of the waveguide. This material may not be hygroscopic and must be protected from weather conditions. For array antennas, this is not possible so easily.

If the frequency is changed, then these distances not correct, the performance of the antenna decreases.

you consider

The proposed antenna is printed on polymer resin substrate FR4 of thickness 1. The rotated square slot and four L slots are printed on one side of the substrate and fed line on the other side of the substrate. Microstrip line width and length are denoted by Wf and Lf. Comparing to the designed antenna in [ 22 ], the proposed antenna has better bandwidth, gain, and smaller size. The details of the optimized design parameter are summarized in Table 1.

The proposed planar microstrip patch antenna was designed and analyzed using a finite element method- FEM- based high-frequency full-wave electromagnetic simulator HFSS from the Ansys Corporation. The designed antenna was fabricated on a recently available 1. The substrate material consists of an epoxy matrix reinforced by woven glass.

This composition of epoxy resin and fibre glass varies in thickness and is direction dependent. One of the attractive properties of polymer resin composites is that they can be shaped and reshaped repeatedly without losing their material properties [ 19 ]. Due to lower manufacturing cost, ease of fabrication, design flexibility, and market availability of the proposed material, it has become popular for use as a substrate in patch antenna design.

Figure 2 shows the several steps involved to construct the epoxy resin polymer substrate FR4 material substrate. Glass raw materials are melted in a furnace and extruded to form fibreglass filaments that are combined into strands of multiple fibre yarn. The yarns are then weaved to form fibreglass cloth. A coupling agent, typically an organosilane, is coated onto the fabric to improve the adhesion between organic resin and inorganic glass.

Resin is obtained from processing the petrochemicals and in its pure uncured form is called A-stage resin. Additives such as curing agents, flame retardants, fillers, and accelerators are added to the resin to tailor the performance of the board. Multiple prepregs are thermally pressed to obtain a core or laminate C-stage resin.

Copper foil is then typically electrodeposited to obtain a copper clad laminate. Thus, a final product of FR4 material substrate has come to market. Figure 3 shows the effect of the different substrate materials on the return loss of the proposed antenna.

It can be clearly seen that the proposed antenna provides a wider bandwidth and acceptable return loss value compared with the three other reported materials. The dielectric constant and loss tangent of epoxy resin fibre is comparatively low so bandwidth is increased. Although the antenna with a ceramic-PTFE composite material substrate gives a lower frequency return loss value because of the higher dielectric, the desired resonances are shifted and it is extremely expensive compared with the proposed material.

Table 2 shows the dielectric properties and achieved bandwidth from the proposed design with different materials. Figure 4 depicts the reflection coefficient of the different types of slots in the ground plane. By using the square slot, there is no resonance. There is a little resonance in that operating band for the triangular slot.

However, a better operating band is achieved by using the pentagon and hexagon slots. The maximum bandwidth is achieved by etching the rotating square slot with diagonal points P 1 and P 2 in the middle of the strip line.

Figure 5 shows the simulated reflection coefficient of the proposed antenna for different values of L 1. The other parameter values used in this simulation remain unchanged. It can be seen that resonance frequencies are shifted upward when L 1 increases and downward when L 1 increases. An important feature of the proposed antenna design is the stimulus of impedance matching caused by the coupling effects between wide slot and feed length and width.

The other parameter remains unchanged as in Table 1. Due to the variety of Lf , both lower and upper resonances have large changes.

This is because increasing the length of Lf significantly increases the total capacitive effect and thus lowers the lowest resonance frequency while decreasing the operating band. The impedance bandwidth changes significantly for variation of Lf because of the sensitivity of the impedance matching to this parameter. However, with the decrease in the length of Lf , the upper resonance shifts upward and impedance bandwidth decreases.

With the length of Lf chosen to be The width of the strip line has a minor effect on the lower resonant mode but a large effect on the upper resonant mode, as shown in Figure 7. It can be clearly seen that there is a minor effect in the reflection coefficient but a major improvement in terms of gain. The insertion of L -shaped slots in the ground plane created some sort of discontinuity which caused the electric current launched by the primary radiator to reroute its path along the conducting surface of the ground.

As a result, the electrical length of the ground is increased. With the strong coupling from the radiator, the ground slots cause a considerable impact on the input impedance. This positive coupling effect is responsible for increasing gain. Figure 10 shows the axial ratio of the proposed antenna.

Generally, the axial ratio is considered to determine antenna polarization. At the six resonant frequencies of 3. It can be understood that the axial ratio decreases with higher frequency due to the low current intensity in the upper side of the patch and opposite direction.

The input impedance and the voltage standing wave ratio are validated in the Smith chart shown in Figure Three of the resonances are in the 2: The Rx values in the Smith chart table represent the input impedance. The curve has a tight resonant loop close to the centre of the Smith chart. This means that the proposed antenna greatly enhances the impedance bandwidth. The markers m1 and m2 represent the start and ending frequencies of the operating band.

Figure 12 shows the surface current distribution of the radiating patch element of the proposed antenna at 3. It has been observed that at the lower band the current intensity is much weaker. The current is more exciting in strip line and wide slotted diagonal points. Specially, the left and right arms of wide slot are more excited. Besides, L slots in ground plane are also more excited than plane area.

Therefore, from the relationship between gain, power and current of the proposed antenna can be validated from the current distribution. Figure 13 shows the radiation efficiency of the proposed antenna. It can be seen that The radiation efficiency at the lower resonant frequencies of 3.

On the other hand, at the upper resonant frequencies of 5. The performance of the proposed antenna was analysed and optimized using a FEM-based high-frequency 3D full-wave electromagnetic simulator, Ansoft's HFSS, and plotted using the scientific graphing and data analysis software OriginPro and Excel. The results of the proposed antenna prototype were measured in a rectangular-shaped 5.

A double ridge guide horn antenna was used as a reference antenna. A turn table with a diameter of 1. Figure 14 shows a photograph of the proposed antenna prototype. Figure 15 shows the simulated and measured return loss of the optimized proposed antenna. A slight discrepancy occurred, which led to the differences between simulated and measured return loss value due to the effect from soldering of the SMA Sub Miniature Version A connector and the loss from the connecting cable.

The results show that the antenna provides a very wide impedance bandwidth of over Detailed numerical and experimental investigations confirm that the achieved impedance bandwidth is limited by the impedance match between the microstrip line height and width, the rotated square slot diagonal points with respect to feed, and the wide square slot arm's length. Figure 16 shows the measured gain of the proposed antenna.

The highest peak gain of the proposed antenna is 4. The average peak gain of the proposed antenna is 4. Figure 17 shows the measured E XZ -H YZ plane normalized radiation pattern of the proposed antenna prototype at different frequencies. It can be undoubtedly seen that good omnidirectional characteristics are obtained for the proposed antenna excited at all other frequencies across the operating band.

Furthermore, the effect of cross-polarization is much smaller than the copolarization desired. Although at higher frequencies, more harmonics are observed mainly in the cross-polarization radiation field, the antenna has a good stable radiation without gain degradation.

Table 3 compares the proposed and some existing antennas. The table shows that the proposed antenna achieves wider bandwidth and higher gain with smaller size compared with the reported antennas, although some of the reported antennas obtain a wide bandwidth and higher gain compromising the overall size and structure. By introducing rotated square slot diagonal points in the middle of the strip line, the impedance bandwidth of the proposed wide-slot antenna can be significantly enhanced.

In addition, the size of the proposed antenna can be reduced. Moreover, the four L -shaped slots are embedded in the ground to increase the gain of the antenna. The proposed structure reveals an average peak gain of 4.

By properly choosing the suitable slot shape position and tuning their dimensions parameter with simulation software, the proposed design with wide operating bandwidth, relative small size, peak gain, and improved radiation pattern is obtained.

The authors declare that there is no conflict of interests regarding the publication of this paper. National Center for Biotechnology Information , U.

Journal List ScientificWorldJournal v. Published online Feb Mandeep , and N. Received Dec 13; Accepted Jan 6. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

This article has been cited by other articles in PMC. This principle relates the radiated fields and impedance of an aperture or slot antenna to that of the field of a dipole antenna. The polarization of a slot antenna is linear. The impedance of the slot antenna Z s is related to the impedance of its complementary dipole antenna Z d by the relation:. The band width of a narrow rectangular slot is equal to that of the related dipole, and is equal to half the bandwidth of a cylindrical dipole with a diameter equal to the slot width.

Although the theory requires an infinite spread conductive surface, the deviation from the theoretical value is small when the surface is greater than the square of the wavelength. The feeding of the slot antenna can be done with ordinary two-wire line. The impedance is dependent on the feeding point, as in a dipole. A shift of the feed point from the center to the edge steadily decreases the impedance.

The application of slot antennas can be versatile. They can replace dipoles e. If a dipole is used for feeding of a parabolic antenna to generate a vertically orientated but horizontally polarized fan beam , then this dipole must be orientated horizontally. This would mean that the edge surfaces of the parabolic reflector will not be sufficiently illuminated, but a lot of energy above and below the reflector would be lost.

In addition, the length of the dipole is extended in a plane, in which is demanding a point like source of radiation for the focus of the parabolic reflector. If this dipole is replaced by a slot antenna, in this case don't appear these disadvantages.

Slot antennas in waveguides provide an economical way of the design of antenna arrays. The position, shape and orientation of the slots will determine how or if they radiate. If slots are cut into the walls, so the current flow is affected more or less depending on the location of the slot. If the slots are sufficiently narrow so the slots B and C Fig.

These two slots radiate not or very little. The slots A and D represent barriers to the current flow. Thus, this current flow acts as an excitation system for the slot, this one acts as radiator. Since the wave in the waveguide moves forward, these drawn lines migrate in the direction of propagation. The slot gets one always alternating voltage potential at its slot edges depending on the frequency in the waveguide.

The power that the slot radiates can be altered by moving the slots closer or farther from the edge.

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Radar Basics. Basics. Slot Antenna. Slot radiators or slot antennas are antennas that are used in the A shift of the feed point from the center to the edge. A microstrip-fed slot antenna was designed using Antenna Magus for the following specifications: 5 GHz centre frequency; 50 Ω input impedance. CPW-FED SQUARE SLOT ANTENNA WITH LIGHTENING-SHAPED FEEDLINE FOR BROADBAND CIRCULARLY POLARIZED RADIATION The slot antenna with enhanced impedance and AR bandwidth was.