Description:TECHNICAL FIELD
[0001] The present disclosure relates, in general, to wideband and multi-frequency slot antennas, and more specifically, relates to a multi-frequency rectangular slot antenna for wireless communication applications.

BACKGROUND
[0002] Recently, the use of wireless communication systems has increased rapidly. With the advent of wireless communication system, it is preferable to accommodate as many standards such as fourth-generation (4G) long term evolution (LTE), worldwide interoperability for microwave access (WiMAX), wireless area network (WLAN) and S/C/X-band standards into a single wireless device. Hence, at microwave frequencies, the microstrip slot antenna is an appropriate choice for implementing such systems. It is also capable of supporting multiple frequency bands with enhanced bandwidth. Also due to its compact size, it is easier to accommodate with other devices.
[0003] Few existing structures in the field of multiband microstrip antennas may include coplanar waveguide (CPW)-fed antenna that is designed using four L-shaped, two U-shaped, and two F-shaped slots for radio-frequency identification (RFID)/Worldwide Interoperability for Microwave Access (WiMAX) and WLAN applications. However, the CPW-fed antenna may suffer from the limitation of lower gain and bands obtained have a narrow bandwidth. Another existing structure may include an inverted T-shaped stub and T-shaped feed patch is designed to create multi-band operation for Global Positioning System (GPS)/WiMAX/WLAN standards. However, the proposed antenna has low return loss in the upper two bands and narrow bandwidth in the lower two bands.
[0004] Therefore, there is a need in the art to provide a means to design a compact antenna that resonates at numerous homogeneous and heterogeneous frequency bands with enhanced bandwidth simultaneously catering to numerous wireless communication applications.

OBJECTS OF THE PRESENT DISCLOSURE
[0005] An object of the present disclosure relates, in general, to wideband and multi-frequency slot antennas, and more specifically, relates to a multi-frequency rectangular slot antenna for wireless communication applications.
[0006] Another object of the present disclosure is to provide an antenna device that supports multiple frequency bands.
[0007] Another object of the present disclosure is to provide an antenna device that can be fabricated easily at low cost.
[0008] Another object of the present disclosure is to provide an antenna device that resonates at numerous homogeneous and heterogeneous frequency bands with enhanced bandwidth simultaneously catering to numerous wireless communication applications.
[0009] Another object of the present disclosure is to provide an antenna device that achieves multiple resonating bands with enhanced impedance bandwidth.
[0010] Yet another object of the present disclosure is to provide an antenna device that is capable of covering all the bands with greater bandwidth.

SUMMARY
[0011] The present disclosure relates, in general, to wideband and multi-frequency slot antennas, and more specifically, relates to a multi-frequency rectangular slot antenna for wireless communication applications.
[0012] In an aspect, the present disclosure provides an antenna device for wireless communication, the device including a rectangular slotted patch configured on a substrate, at least two E-shaped stubs embedded on any or a combination of left side and right side of the rectangular slotted patch, an inverted T-shaped stub having at least two horizontal strips folded on both sides is embedded in an upper edge of the rectangular slotted patch, and a feed line is employed at backside of the substrate, one or more patches of different size is added to form a combination of staircase shaped feed line, the feed line operable to excite the antenna device, wherein upon excitation, the at least two E-shaped stubs and the inverted T-shaped stub generate a plurality of frequency bands with enhanced impedance bandwidth for communication.
[0013] In an embodiment, the antenna device can include a radiating patch on one side of the substrate and ground on the other side of the substrate.
[0014] In another embodiment, the radiating patch can include at least two E-shaped stubs and the inverted T-shaped stub.
[0015] In another embodiment, the plurality of frequency bands can include any or a combination of S-band, C-band and X-band.
[0016] In another embodiment, the antenna device is fabricated using FR-4 substrate with dimensions of 56 × 44 mm2
[0017] In another embodiment, the at least two E-shaped stubs can include inner E-shaped stub and outer E-shaped stub embedded on left side and right side of the rectangular slot.
[0018] In another embodiment, the inner E-shaped stub is smaller in dimension than the outer E-shaped stub.
[0019] In another embodiment, the inverted T-shaped stub comprises inner inverted T-shaped stub and outer inverted T-shaped stub, wherein the inner inverted T-shaped stub is smaller than the outer inverted T-shaped stub.
[0020] In another embodiment, the inner inverted T-shaped stub is embedded in the upper edge of the rectangular slot results in the better return loss and improved bandwidth for all bands.
[0021] In another embodiment, the antenna device comprises a rectangular element embedded to staircase feed line and a slot is etched in the middle of staircase feed line to achieve enhanced bandwidth and lower return loss.
[0022] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The following drawings form part of the present specification and are included to further illustrate aspects of the present disclosure. The disclosure may be better understood by reference to the drawings in combination with the detailed description of the specific embodiments presented herein.
[0024] FIG. 1A illustrate exemplary front view and rear view of the antenna device, in accordance with an embodiment of the present disclosure.
[0025] FIG. 1B illustrate an exemplary dimension of the antenna device, in accordance with an embodiment of the present disclosure.
[0026] FIG. 1C illustrate an exemplary view of the E-shape stub of the antenna device, in accordance with an embodiment of the present disclosure.
[0027] FIG. 1D illustrate an exemplary view of the Inverted T-shape stub of the antenna device, in accordance with an embodiment of the present disclosure.
[0028] FIG. 1E illustrate exemplary view of the feed line of the antenna device, in accordance with an embodiment of the present disclosure.
[0029] FIG. 1F illustrate exemplary side view of the antenna device, in accordance with an embodiment of the present disclosure.
[0030] FIG. 2A illustrates an exemplary view of different elements in the rectangular slot, in accordance with an embodiment of the present disclosure.
[0031] FIG. 2B illustrates an exemplary view of addition of smaller E-shaped stubs in the rectangular slot, in accordance with an embodiment of the present disclosure.
[0032] FIG. 2C illustrates an exemplary view of addition of rectangle shaped element to staircase feedline, in accordance with an embodiment of the present disclosure.
[0033] FIG. 2D illustrates an exemplary view of addition of a smaller stub in inverted T-stub, in accordance with an embodiment of the present disclosure.
[0034] FIG. 3A illustrates an exemplary view of effect of varying length L5 on the various bands, in accordance with an embodiment of the present disclosure.
[0035] FIG. 3B illustrates an exemplary view of effect of varying length L10 on the various bands, in accordance with an embodiment of the present disclosure.
[0036] FIG. 3C illustrates an exemplary view of effect of varying length L7 on the various bands, in accordance with an embodiment of the present disclosure.
[0037] FIG. 4 illustrates an exemplary view of simulation and measured return loss, in accordance with an embodiment of the present disclosure.
[0038] FIG. 5 illustrates an exemplary view of radiation efficiency of the antenna device in percent, in accordance with an embodiment of the present disclosure.
[0039] FIG. 6 illustrates an exemplary view of simulated and measured gain of the antenna device, in accordance with an embodiment of the present disclosure.
[0040] FIGs.7A-7D illustrate the surface current distribution at the desired resonant frequencies, in accordance with an embodiment of the present disclosure.
[0041] FIG. 8 illustrates an exemplary view of simulation and measured radiation pattern at different frequencies, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0042] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[0043] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0044] The present disclosure relates, in general, to wideband and multi-frequency slot antennas, and more specifically, relates to a multi-frequency rectangular slot antenna for wireless communication applications. The present disclosure relates to compact antenna that is designed using two additional E-shaped stubs, an inverted T-shaped stub on the main radiating patch slot. The antenna is excited using staircase shaped feed line on the rectangular reduced ground plane to achieve improved impedance matching. The present disclosure can be described in enabling detail in the following examples, which may represent more than one embodiment of the present disclosure.
[0045] FIG. 1A illustrate exemplary front and rear view of the antenna device, in accordance with an embodiment of the present disclosure.
[0046] Referring to FIG. 1A, antenna device 100 (also referred to as device 100, herein) configured for 4G-LTE/WiMAX/WLAN and S/C/X-band applications. The device 100 may include rectangular slotted patch 102 also interchangeable referred to as rectangular slot 102, at least two E-shaped stubs 104, an inverted T-shaped stub 106 and a staircase shaped feed line 108. The antenna device 100 can achieve multi-band resonance with enhanced bandwidth. The antenna device 100 can cover all the bands with greater bandwidth. The radiation patterns for the designed antenna are measured in an anechoic chamber and are found to agree well with simulated results.
[0047] In an exemplary embodiment, the total size of the antenna device 100 is around 56 × 44 mm2 and the radiating portion of the antenna device 100 has a dimension of around 48 × 18 mm2. The antenna device 100 can be fabricated using FR-4 substrate 112 (as illustrated in FIG. 1F) with dimensions of 56 × 44 mm2. The FR-4 is glass-reinforced epoxy laminate material, which is flame resistant and is easily available in sheet form. The thickness of the FR-4 sheet is chosen to be 1.6 mm with relative permittivity (er) of 4.4 and a loss tangent of 0.02. The antenna device 100 may include radiating patch on one side of the substrate 112 and ground 114 on the other side of the substrate 112. The patch is formed of perfect electrical conductor (PEC) material with a thickness of 0.035 mm. The photolithography and wet etching process used to manufacture the proposed multi-frequency rectangular slot antenna.
[0048] FIG. 1B illustrate an exemplary dimension of the antenna device, in accordance with an embodiment of the present disclosure. As shown in FIG. 1B, rectangular slot 102 with dimension of 48 × 18 mm2 is cut from the radiating patch. The rectangular slot 102 can be configured on the substrate 112.
[0049] FIG. 1C illustrate an exemplary view of the E-shape stub of the antenna device, in accordance with an embodiment of the present disclosure. As shown in FIG. 1C, at least two E-shaped stubs 104 are attached to both left side and right side of the rectangular slot 102. At least two E-shaped stubs 104 can include an inner E-shaped stub and an outer E-shaped stub embedded on the left side and right side of the rectangular slot 102. The inner E-shaped stub is smaller in dimension than the outer E-shaped stub.
[0050] FIG. 1D illustrate an exemplary view of the inverted T-shape stub of the antenna device, in accordance with an embodiment of the present disclosure. As shown in FIG. 1D, the inverted T-shaped stub 106 with its two horizontal strips folded on both sides is embedded in the upper edge of the rectangular slot 102. The inverted T-shaped stub 106 can include an inner inverted T-shaped stub and outer inverted T-shaped stub, where the inner inverted T-shaped stub is smaller than the outer inverted T-shaped stub. The inner inverted T-shaped stub is embedded in the upper edge of the rectangular slot 102 results in better return loss and improved bandwidth for all bands. The proposed structure can achieve multiple resonating bands with enhanced impedance bandwidth.
[0051] FIG. 1E illustrate exemplary view of the feed line of the antenna device, in accordance with an embodiment of the present disclosure. As shown in FIG. 1E, the staircase feed line 108 of thickness 0.035 mm and width (wf) of 1.76 mm is implemented on the backside side of the substrate 112 which helps to achieve an impedance of 50 O. The different size of one or more patches can be added one after another forming a staircase shaped feed line 108 structure. A slot is etched in the middle of the feed line patch to further improve impedance matching.
[0052] FIG. 1F illustrate exemplary side view of the antenna device, in accordance with an embodiment of the present disclosure. As shown in FIG. 1F, the antenna device 100 may include radiating patch on one side of the substrate 112 and ground 114 on the other side of the substrate 112. The patch is formed of perfect electrical conductor (PEC) material with a thickness of 0.035 mm.
[0053] The initial design may include a rectangular patch with dimensions calculated using basic design equations based on transmission line model. The solid rectangular patch is then cut from its center to form a slotted patch antenna. The different elements such as at least two E-shaped stubs 104, the inverted T-shaped stub 106 are added to the slotted patch design to achieve the desired resonating bands and are referred as structural variations.
[0054] In another embodiment, the slotted patch, stubs have been employed as radiating elements to excite the quad resonance mode. For the proposed antenna, the effective dielectric constant (eeff) and the ith resonance frequency (fri) corresponding to various stubs employed are calculated using Equations (1) and (2) as follows:
(1)
(2)
[0055] where er is the dielectric constant of substrate, c is speed of light, and Lsi is the total length of the stub elements responsible for resonance. The theoretical resonant frequencies can be calculated using Equations (1) and (2). The effective dielectric constant using Equation (2) is calculated to be 2.7. To achieve desired resonance, the total length of the radiating element must be quarter of the guided wavelength (?g) in the medium. Now, total length (Ls1) of the rectangular slot is calculated using Equation (3)
[0056] (3)
where, the length Ls1 using Equation (3) is calculated to be 56 mm as given in Table 2. The first theoretical resonance frequency fr1 calculated using Equation (1) is found to be 1.38 GHz, and the CST simulated resonance is found to be 1.67 GHz.
[0057] The antenna device 100 is capable of operation at 2.24, 4.2, 5.25, and 9.3 GHz frequency bands. The antenna device 100 is useful for 4G LTE/WiMAX/WLAN wireless standard. It also supports space to earth communications and direct to home satellite (DTH) services in S-band, aeronautical and radio navigation in C-band. Also, fixed satellite, earth explorer satellite, mobile satellite, meteorological satellite, mobile satellite, space research, radiolocation, aeronautical radio navigation, maritime radio navigation, meteorological, amateur aids is operating in X-band band.
[0058] The embodiments of the present disclosure described above provide several advantages. The one or more of the embodiments provide the antenna device 100 that includes inverted T-shaped stub 106 and two E-shaped stubs 104 are used to generate multiple frequency bands for 4G LTE, WiMAX, WLAN, and S/C/X-band applications. The antenna device 100 can resonate at numerous homogeneous and heterogeneous frequency bands with enhanced bandwidth simultaneously catering to numerous wireless communication applications. The antenna device 100 can achieve multiple resonating bands with enhanced impedance bandwidth and can be capable of covering all the bands with greater bandwidth. Further, the antenna device 100 can be fabricated easily at low cost.
[0059] FIG. 2A illustrates an exemplary view of different elements in the rectangular slot, in accordance with an embodiment of the present disclosure.
[0060] Referring to FIG. 2A, in the slotted patch, the at least two E-shaped stubs 104 and one inverted T-shape stub 106 are embedded in the upper edge of the rectangular slot 102. The staircase shaped feed line 108 can be employed at the backside of substrate 112 to excite the antenna device 100 resulting in generation of multiple bands at 1.42, 2.1, 3.01, and 4.26 GHz. The simulated return loss (S11) and impedance bandwidth (MHz) are given in the Table 1
Band-1
(1.37-1.48 GHz) Band-2
(2.13-2.45 GHz) Band-3
(2.90-3.40 GHz) Band-4
(4.16-6.27 GHz)
Resonant frequency 1.42 2.1 3.01 4.26
Return loss (dB) -20.47 -24.62 -14.07 -29.42
Bandwidth (MHz) 110 320 500 2560
Table 1: First step simulation-based return loss and bandwidth
[0061] The total length, Ls2 corresponding to added E-shaped stubs are calculated using Equation (4)
(4)
[0062] FIG. 2B illustrates an exemplary view of addition of smaller E-shaped stubs in the rectangular slot, in accordance with an embodiment of the present disclosure. Referring to FIG. 2B, smaller E-shaped stub is embedded on either side of the E arm. The structure of inner E arm stubs is same as previous but smaller in dimension. It changes the path length of the structure, which causes the currents to redistribute on the structure resulting in the shifting of band 3 and band 4 toward higher frequency. No change is made in the structure or geometry of the inverted T-shaped stub 106 and the staircase shaped feed line 108. The return loss parameter (S11) and impedance bandwidth is measured and given in the Table 2.
Band-1
1.37-1.45 GHz Band-2
(1.72-1.82 GHz) Band-3
(5.12-5.77 GHz) Band-4
(6.99-7.42 GHz)
Resonant frequency 1.4 1.77 5.26 7.13
Return loss (dB) -13.78 -17.89 -18.38 -15.67
Bandwidth (MHz) 80 100 650 430
Table 2: Second step simulation-based return loss and bandwidth
[0063] FIG. 2C illustrates an exemplary view of addition of rectangle shaped element to staircase feedline, in accordance with an embodiment of the present disclosure. Referring to FIG. 2C, rectangle shaped element can be added to staircase feedline 108. In the third step, one more rectangular element is embedded to staircase feed line 108 and a slot is etched in the middle of staircase feed line 108 to achieve enhanced bandwidth and lower return loss. Further, the dimension of smaller E-shaped stub has been optimized to achieve the desired bandwidth of band 1 and band 4. The return loss parameter (S11) and impedance bandwidth is measured and given in the Table 3.
Band-1
(2.25-2.95 GHz) Band-2
(4.04-4.24 GHz) Band-3
(4.99-5.31 GHz) Band-4
(7.96-10.17 GHz)
Resonant frequency 2.66 4.13 5.14 9.3
Return loss (dB) -23.94 -18.35 -33.64 -35.99
Bandwidth (MHz) 674 208 318 2207
Table 3: Third step simulation-based Return loss and Bandwidth
[0064] FIG. 2D illustrates an exemplary view of addition of a smaller stub in inverted T-stub, in accordance with an embodiment of the present disclosure. Referring to FIG. 2D, at least one smaller inverted T-shaped stub is embedded in the antenna design. The addition of stub results in the better return loss and improved bandwidth for all bands. The return loss parameter (S11) and impedance bandwidth of various bands are given in the Table 4.

Band-1
(2.12-2.90 GHz) Band-2
(4.07-4.31 GHz) Band-3
(5.08-5.40 GHz) Band-4
(7.90-10.19 GHz)
Resonant frequency 2.24 4.2 5.25 9.3
Return loss (dB) -37.17 -20.81 -21.22 -39.21
Bandwidth (MHz) 780 240 320 2290
Table 4: Final step simulation-based return loss and bandwidth
[0065] FIG. 3A illustrates an exemplary view of effect of varying length L5 on the various bands, in accordance with an embodiment of the present disclosure. To investigate the effect on bandwidth and return loss, the length L5 of the outer E-shaped stubs is varied on either side of the rectangular slot from 6.5 to 7.5 mm with a step of 0.5 mm. It is evident from the varying length L5 has major effect on the band 3 and band 4 but minor impacts on band 1 and band 2.
[0066] FIG. 3B illustrates an exemplary view of effect of varying length L10 on the various bands, in accordance with an embodiment of the present disclosure. To understand the effect of varying the length of lower end of staircase feedline 108 on the resonant frequency, the length L10 is varied from 16 to 18 mm in steps of 1 mm. The parameter L10 has major effect on all the resonant bands.
[0067] FIG. 3C illustrates an exemplary view of effect of varying length L7 on the various bands, in accordance with an embodiment of the present disclosure. To observe the effect of varying the length of the inner E-shaped stubs on the resonant frequency, the length L7 is varied from 5.5 to 6.5 mm in steps of 0.5 mm. the parameter L7 has major effect on the band 3 and band 4 but minor effect in the band 1 and band 2.
[0068] FIG. 4 illustrates an exemplary view of simulation and measured return loss, in accordance with an embodiment of the present disclosure. The simulation and measured return loss of the antenna device 100 illustrated. The simulated results in terms of S11 parameter are obtained using CST microwave studio version and are compared with the measured results obtained after testing the fabricated antenna using vector network analyzer (VNA).
[0069] FIG. 5 illustrates an exemplary view of radiation efficiency of the antenna device in percent, in accordance with an embodiment of the present disclosure. As illustrated in FIG. 5, it is observed that the antenna device 100 exhibits efficiency of nearly 55% at 2.24, 4.2, and 5.25 GHz whereas it is 63% at 9.3 GHz.
[0070] FIG. 6 illustrates an exemplary view of simulated and measured gain of the antenna device, in accordance with an embodiment of the present disclosure. FIG. 6 characterize the overall performance of the antenna device 100. It is observed that both the results agree to each other, however, a slight deviation is observed in the lower band (2.2 GHz) which may be attributed to soldering inaccuracies.
[0071] FIGs.7A-7D illustrate the surface current distribution at the desired resonant frequencies, in accordance with an embodiment of the present disclosure. It is evident from FIG. 7A that the surface current is mainly distributed at the edges of the rectangular slot and the gap between the inverted T-shaped stub and the upper edge of the slot at 2.24 GHz band. FIG. 7B shows that the surface current is mainly concentrated at the upper portion of the E-shaped stubs present on either side of the rectangular slot and on the slots etched in the staircase feed line at 4.2 GHz band. From FIG. 7C, it is observed that the surface current at 5.25 GHz band is distributed in the gap between the inner and outer E-shaped stubs on either side as well as on the slots etched in the staircase feed line. For 9.3 GHz band, FIG. 7D shows that the surface current is distributed somewhat in the central portion of the inner and the outer E-shaped stub. It is observed from the return loss measurements that multiband enhanced bandwidth antenna has four frequency bands resonating at 2.24, 4.2, 5.25, and 9.3GHz bands, respectively. Hence, the proposed multiband antenna resonates at the following bands such as S-Band (2.17-2.82 GHz), C-Band (4.1-4.38 GHz), C-Band (5.04-5.61 GHz) and X-Band (7.9-10.28 GHz).
[0072] FIG. 8 illustrates an exemplary view of simulation and measured radiation pattern at different frequencies, in accordance with an embodiment of the present disclosure. The proposed antenna structure is observed to resonate at 2.24, 4.2, 5.25, and 9.3 GHz, respectively covering Wi-MAX (802.16e), space to earth communications, 4G-LTE, IEEE 802.11b/g WLAN systems defined for S-band applications. Additionally, the proposed antenna also covers aeronautical and radio navigation applications (4.1-4.38 GHz), uncoordinated indoor systems (4.2-4.28 GHz), IEEE 802.11a WLAN system (5.04-6.1 GHz) defined for C-band applications and X-band applications (7.9-10.28 GHz).
[0073] It will be apparent to those skilled in the art that the antenna device 100 of the disclosure may be provided using some or all of the mentioned features and components without departing from the scope of the present disclosure. While various embodiments of the present disclosure have been illustrated and described herein, it will be clear that the disclosure is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without departing from the scope of the disclosure, as described in the claims.

ADVANTAGES OF THE PRESENT DISCLOSURE
[0074] The present disclosure provides an antenna device that supports multiple frequency bands.
[0075] The present disclosure provides an antenna device that can be fabricated easily at low cost.
[0076] The present disclosure provides an antenna device that resonates at numerous homogeneous and heterogeneous frequency bands with enhanced bandwidth simultaneously catering to numerous wireless communication applications.
[0077] The present disclosure provides an antenna device that achieves multiple resonating bands with enhanced impedance bandwidth.
[0078] The present disclosure provides an antenna device that is capable of covering all the bands with greater bandwidth.

We Claims:

1. An antenna device (100) for wireless communication, the device comprising:
a rectangular slotted patch (102) configured on a substrate (112);
at least two E-shaped stubs (104) embedded on any or a combination of left side and right side of the rectangular slotted patch;
an inverted T-shaped stub (106) having at least two horizontal strips folded on both sides is embedded in an upper edge of the rectangular slotted patch; and
a feed line (108) is employed at backside of the substrate (112), one or more patches of different size is added to form a combination of staircase shaped feed line, the feed line operable to excite the antenna device,
wherein upon excitation, the at least two E-shaped stubs and the inverted T-shaped stub generate a plurality of frequency bands with enhanced impedance bandwidth for communication.
2. The antenna device as claimed in claim 1, wherein the antenna device (100) comprises a radiating patch on one side of the substrate (112) and ground (114) on the other side of the substrate.
3. The antenna device as claimed in claim 1, wherein the radiating patch comprises at least two E-shaped stubs (104) and the inverted T-shaped stub (106).
4. The antenna device as claimed in claim 1, wherein the plurality of frequency bands comprises any or a combination of S-band, C-band and X-band.
5. The antenna device as claimed in claim 1, wherein the antenna device (100) is fabricated using FR-4 substrate with dimensions of 56 × 44 mm2
6. The antenna device as claimed in claim 1, wherein the at least two E-shaped stubs (104) comprise inner E-shaped stub and outer E-shaped stub embedded on left side and right side of the rectangular slotted patch (102).
7. The antenna device as claimed in claim 1, wherein the inner E-shaped stub is smaller in dimension than the outer E-shaped stub.
8. The antenna device as claimed in claim 1, wherein the inverted T-shaped stub (106) comprises inner inverted T-shaped stub and outer inverted T-shaped stub, wherein the inner inverted T-shaped stub is smaller than the outer inverted T-shaped stub.
9. The antenna device as claimed in claim 1, wherein the inner inverted T-shaped stub is embedded in an upper edge of the rectangular slotted patch (102) results in the better return loss and improved bandwidth for all bands.
10. The antenna device as claimed in claim 1, wherein the antenna device comprises a rectangular element embedded to staircase feed line and a slot is etched in the middle of staircase feed line to achieve enhanced bandwidth and lower return loss.