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Bandwidth Enhancement and Frequency Scanning Array Antenna Using Novel UWB Filter Integration Technique for OFDM UWB Radar Applications in Wireless Vital Signs Monitoring MuhibUr Rahman 1 , Mahdi NaghshvarianJahromi 2,3, * , Seyed Sajad Mirjavadi 4 Abdel Magid Hamouda 4 1 2 3 4

*

and

Department of Electrical Engineering, Polytechnique Montreal, Montreal, QC H3T1J4, Canada; [email protected] Department of Electrical and Computer Engineering, McMaster University, Hamilton, ON L8S4L8, Canada Health Technology Incubator, Jahrom University of Medical Sciences, 74148-46199 Jahrom, Iran Department of Mechanical and Industrial Engineering, College of Engineering, Qatar University, Doha 2713, Qatar; [email protected] (S.S.M.); [email protected] (A.M.H.) Correspondence: [email protected]; Tel.: +1-289-680-3832

Received: 1 September 2018; Accepted: 14 September 2018; Published: 19 September 2018







Abstract: This paper presents the bandwidth enhancement and frequency scanning for fan beam array antenna utilizing novel technique of band-pass filter integration for wireless vital signs monitoring and vehicle navigation sensors. First, a fan beam array antenna comprising of a grounded coplanar waveguide (GCPW) radiating element, CPW fed line, and the grounded reflector is introduced which operate at a frequency band of 3.30 GHz and 3.50 GHz for WiMAX (World-wide Interoperability for Microwave Access) applications. An advantageous beam pattern is generated by the combination of a CPW feed network, non-parasitic grounded reflector, and non-planar GCPW array monopole antenna. Secondly, a miniaturized wide-band bandpass filter is developed using SCSRR (Semi-Complementary Split Ring Resonator) and DGS (Defective Ground Structures) operating at 3–8 GHz frequency band. Finally, the designed filter is integrated within the frequency scanning beam array antenna in a novel way to increase the impedance bandwidth as well as frequency scanning. The new frequency beam array antenna with integrated band-pass filter operate at 2.8 GHz to 6 GHz with a wide frequency scanning from the 50 to 125-degree range. Keywords: frequency scanning fan beam array antenna; wide-band applications; miniaturized band-pass filter; DGS (Defective Ground Structures); grounded coplanar waveguide (GCPW); grounded reflector; SCSRR (Semi-Complementary Split Ring Resonator)

1. Introduction The Federal Communication Commission have assigned 3.1 GHZ to 10.6 GHz frequency band for Ultra-Wide Band (UWB) wireless communication [1]. Within this technology, two subsets of UWB exist, termed as (i) UWB orthogonal frequency division multiple access (OFDM-UWB) having frequency band of (3.43–4.48 GHz) and (6.60–10.2 GHz), (ii) Direct sequence UWB (DS-UWB) (3.1–4.85 GHz) and (6.20–9.70 GHz) [2]. In this regard, different array antennas with sub-radiators and extended reflector for different applications have been developed in the past decade [3–8]. The non-parasitic reflector is first presented in References [8,9]. In Reference [8], they simulated a fan beam array antenna to operate in Ku band while in [9] they developed a millimeter wave antenna having lightweight for the 60 GHz frequency

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band. These antennas achieve higher gain having more than 13 dBi, however, they suffer from narrower input impedance. Therefore, it is necessary to develop a new fan beam array antenna with wider impedance bandwidth performance. In References [10,11], the authors reported fractal antennas, for broadening impedance bandwidth using CPW feeding technique. In Reference [11], the authors applied the GCPW concept on the fractal antenna to achieve a wider bandwidth. Also, designing a frequency scanning antenna is a hot topic and many frequency scanning antennas have been developed in the literature [12–14]. Recently, in Reference [15] they reported an antenna for frequency scanning by utilizing a strip-line as an intended transmission line for the coupler structure. This antenna can be shifted to different angles based on the coupler structure which limits the antenna performance. Nevertheless, an antenna having the capability of both scanning and enhanced bandwidth is reported so far. Different bandstop filters integrated with microstrip antennas have been reported in References [16–19] for band-notching purposes, however, no integrated filter with fan beam array antenna has also been reported so far. This manuscript will introduce the concept of bandpass filter integration in array antennas for enhancing bandwidth performance. The concept of bandwidth enhancement and antenna miniaturization using reactive impedance surface (RIS) has been introduced in Reference [20]. They designed different planar antennas such as patch and dipole on RIS and compared their characteristics with the same antennas over PMC and PEC. Similarly, in Reference [21] bandwidth and gain enhancement of Microstrip antenna is achieved using planar patterned metamaterial concept. Also, in Reference [22] wide bandwidth antenna as a passive antenna sensor is implemented and tested for temperature sensing without any electronics in the design. In this paper, we first introduced a fan beam array antenna that has the capability to operate at the 3.3 GHz and 3.5 GHz frequency bands. This antenna basically comprises of three components having a CPW fed line, GCPW radiating element, and grounded reflector. It is displayed that the grounded reflector greatly minimizes the back lobe level. Secondly, a miniaturized wideband bandpass filter is designed and fabricated which operate from 3 GHz to 8 GHz frequency band. This filter is specially designed for integration purposes. Finally, the fan beam array antenna and a bandpass filter is integrated in a very novel way to enhance the bandwidth and increase frequency scanning. The technique of integration is based on the placement of the filter in CPW fed line, but opposite to the excitation side of the feedline. The filter is matched with the array antenna and operate from 2.8 GHz to 6 GHz frequency range. It is seen that a wide frequency scanning is achieved by placing the proposed filter at the CPW fed line. The equivalent circuit of the integrated bandpass filter as well as proposed antenna, is also provided for validation purpose. The comparison between the proposed antenna and some related designs in terms of designing technique, frequency scanning, and bandwidth enhancement is summarized in Table 1. Table 1. Comparison between proposed work and related work published in literature. Operating Freq.

Frequency Scanning

Technique Implemented

[9]

60 GHz

N/A

Reflector back array technique

[11]

4.65–10.5 GHz

N/A

GCPW Technique

[20]

1.8–1.95 GHz

N/A

RIS Technique

[23]

1.7–2.2 GHz

N/A

Non-parasitic grounded reflector Technique

This work

2.8–6 GHz

75 degree

Bandpass filter integration Technique with combination of GCPW, grounded reflector, and CPW feed line

The arrangement of the manuscript is carried out in the following manner: Section 2 deals with the development of fan beam array antenna. Section 3 deals with the design guidelines of the developed fan beam antenna array. The measured and simulated results of the developed fan beam antenna array are shown in Section 4. The development of a miniaturized wideband bandpass filter with simulated

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and measured response is carried out in Section 5. The development of bandwidth-enhanced frequency scanningSection proposed fan beam antenna isofcarried out in Section 6. Section deals withwhich measured antenna. 8 deals with array the application the proposed antenna in target7 detection, is and simulated and results of the proposed frequency scanning fan beam array antenna. Section 8 deals followed by the Conclusion. with the application of the proposed antenna in target detection, which is followed by the Conclusion. 2. Development of Fan Beam Array Antenna 2. Development of Fan Beam Array Antenna Three different concepts are combined to develop a fan beam antenna having a non-parasitic Three grounded-reflector, different concepts are combined to develop fan beam antennaelement having a structured CPW feed network, anda GCPW radiation asnon-parasitic shown in structured grounded-reflector, CPW feed network, and GCPW radiation element as shown Figure 1. Figure 1. The developed linear fan beam array antenna is designed to operate at 3.5 GHz in WiMAX The developed linear fan beam array antenna is designed to operate at 3.5 GHz application. Figure 1 display the perspective outlook of the fan beam antenna arrayWiMAX with andapplication. without Figure 1 display the perspective outlook of the fan beam antenna array with and without reflector. a reflector. The reflector and radiating element are perpendicularly linked to the CPW line asashown The reflector and radiating element are perpendicularly linked to the CPW line as shown in Figure 1b. in Figure 1b.

Figure1.1.CPW-feed CPW-feednon-planar non-planarlinear lineararray array(a)(a)Fan Fan beam antenna array without reflector (perspective Figure beam antenna array without reflector (perspective view); (b) Fan beam antenna array with reflector (perspective view). view); (b) Fan beam antenna array with reflector (perspective view).

The array factor for the far zone of the linear array is made in-line with the X-axis using the The array factor for the far zone of the linear array is made in-line with the X-axis using the following equation [18–24] following equation [18–24] 2π M

AF (θ, φ) =

∑ M



jn(

λ

d sin θ cos φ+α)

an e jn ( 2π d sin θ cosφ +α ) λ

(1)

(1) AF (θ , φ ) = an e where, represents the angles b/w the intended n =1axis of the designed array and observer radial vector with respect to the origin, a is the excitation amplitude, α represents wave progression between array where, represents the anglesn b/w the intended axis of the designed array and observer radial vector elements, d is the distance between any two array elements, and is the designed wavelength of the with respect to the origin, an is the excitation amplitude, α represents wave progression between array array elements, and λ is the designed wavelength of the array. elements, d is the distance between any two array elements, and λ is the designed wavelength of The four elements linear aligned array is developed by selecting d = 0.5λ and α = −π/6. Figure 2 the array. represents the array factor developed in the xy-plane with max. SLL (Side lobe level) of −11.31 dB with The four elements linear aligned array is developed by selecting d = 0.5λ and α = −π / 6 . Figure a 26.7 degree of beam width. Figure 2 also shows the simulated pattern of the monopole element array 2 represents the array factor developed in the xy-plane with max. SLL (Side lobe level) of −11.31 dB backed by the reflector and without a reflector. It is clear from Figure 1 that the grounded-reflector has with a 26.7 degree of beam width. Figure 2 also shows the simulated pattern of the monopole element greatly minimized back lobe which is very advantageous. array backed by thethe reflector andlevel, without a reflector. It is clear from Figure 1 that the groundedPreviously in Reference [23], a fan-beam antenna is realized utilizing six elements conventional reflector has greatly minimized the back lobe level, which is very advantageous. planar monopole array antenna and feed network. Dolph-Tschebyscheff is employed Previously in Reference [23], a fan-beam antenna is realized utilizing sixdistribution elements conventional and a broadband array feed network is designed to satisfy beneficial input impedance bandwidth planar monopole array antenna and feed network. Dolph-Tschebyscheff distribution is employed requirements in the frequency range 1.70–2.20 GHz However, all input of these antennasbandwidth are designed and a broadband array feed network is designed to [23]. satisfy beneficial impedance using planar radiation elements. In addition, planar monopole elements need a symmetrical reflector. requirements in the frequency range 1.70–2.20 GHz [23]. However, all of these antennas are designed Therefore, spatial dimensions can be reduced by conventional non-planar monopole antenna as a using planar radiation elements. In addition, planar monopole elements need a symmetrical reflector. radiation elements, and this is mainly because the image theory [24], monopole so the reflector height Therefore, spatial dimensions can be reduced by of conventional non-planar antenna as a is reduced to half. Even so, non-planar array antennas do not possess easy installation, lightweight, radiation elements, and this is mainly because of the image theory [24], so the reflector height is or cheaptocharacteristics, mainly because their feed Ineasy order to addresslightweight, these problems, reduced half. Even so, non-planar array of antennas do network. not possess installation, or n =1

cheap characteristics, mainly because of their feed network. In order to address these problems, we

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have combined a grounded coplanar waveguide (GCPW) radiating element with a CPW fed line, have combined a grounded coplanar waveguide (GCPW) radiating element with a CPW fed line, which is the bestachoice to address suchwaveguide feeding network problems. have combined grounded coplanar (GCPW) radiating element with a CPW fed line, which is combined the best choice to address such feeding network problems. we have a grounded coplanar waveguide (GCPW) radiating element with a CPW fed line, which is the best choice to address such feeding network problems. which is the best choice to address such feeding network problems.

Figure 2. Radiation pattern at f = 3.5 GHz for a linear array having four elements in case of isotropic, Figure 2. Radiation pattern at f = 3.5 GHz for a linear array having four elements in case of isotropic, actual monopole, grounded the proposed frequency scanning fan beam array Figure pattern at f = 3.5reflector Figure 2. 2. Radiationand GHz forofa linear array having four elements in case of isotropic, actual monopole, and grounded reflector of the proposed frequency scanning fan beam array antenna. actual grounded reflector of the frequency scanning fan beam array antenna. actual monopole, monopole,and and grounded reflector of proposed the proposed frequency scanning fan beam array antenna. antenna.

3. Design Guidelines of Fan Beam Array Antenna 3. Design Guidelines of Fan Beam Array Antenna 3. Design Guidelines of Fan Beam Array Antenna The fan beam array is developed and its CPW fed line is shown in Figure 3a while the 3. Design Guidelines of antenna Fan Beam Array Antenna The fan beam array antenna is developed and its CPW fed line is shown in Figure 3a while the radiating element in and Figure 3b. The is comprised of3a three main The fan beamwith arrayreflector antennaisisrevealed developed its CPW fedantenna line is shown in Figure while the radiating element in and Figure 3b. The is comprised three main The fan beamwith arrayreflector antenna isis revealed developed its CPW fedantenna line is shown in Figureof3a while the components having GCPW radiating element, CPW feed line,antenna and grounded reflector. The CPW radiating element with reflector is revealed in Figure 3b. The is comprised of three main components havingwith GCPW radiating element,inCPW feed3b. line, and grounded reflector. The CPWmain feed radiating element reflector is revealed Figure The antenna is comprised of three feed line and having radiating element part iselement, designed using Rogers RO4003 substrate with loss of components GCPW radiating CPW feed line, and grounded reflector. Thetangent CPW feed line and radiating element is designed using Rogers substrate with loss tangent of 0.0027 components having GCPWpart radiating element, CPW feedRO4003 line, and grounded reflector. The CPW feed 0.0027 and dielectric constant 3.38. Theusing otherRogers parameters are: d1 = 42.86 Gcpw = 0.20 mm, line and radiating element part of is designed RO4003 substrate withmm, loss tangent of 0.0027 and dielectric constant of 3.38. other parameters are: RO4003 d1 = 42.86substrate mm, Gcpwwith = 0.20 mm, wg = 30.0 mm, line and radiating element partThe is designed using Rogers loss tangent of 0.0027 w = dielectric 30.0 mm, constant lg = 165.0 mm,The wcpw = 2.80 mm, G1are: = d12.25 mm, l1 = 7.40 mm, w1w=g =1.80 mm, and of 3.38. other parameters 1 = 42.86 mm, G cpw = 0.20 mm, 30.0 g land g = 165.0 mm, constant wcpw = 2.80ofmm, 1 = 12.25 l1 = 7.40are: mm,d1w=1 42.86 = 1.80mm, mm,Gl2cpw = =11.93 dielectric 3.38.GThe othermm, parameters 0.20mm, mm, w w2g == 0.25 30.0 mm, ll2g = 165.0 11.93 mm, mm, w wcpw ==0.25 mm, w l1==11.52 l4 1== 14.83 mm,lw = 8.5 mm, 20.4 mm, 2.80mm, mm,l3G= 1 =6.22 12.25 mm, 7.40 mm, w 1.80 mm, 2= 11.93 mm, w ws2 = 0.25 l3g = 6.22 3 cpw =2 11.52 = 114.83 mm, w43l=1 =8.5 mm, ws w = 120.4 mm, h3 =l2 19.0 mm, h2 =w2.0 and 165.0mm, mm,ww = 2.80mm, mm,l4 G = 12.25 mm, 7.40 mm, = 1.80 mm, =4 11.93 mm, 2 = mm, 0.25 mm, hl33 ==6.22 19.0mm, mm,wh32 ==11.52 2.0 mm, = 35.0 fabricated frequency array is mm,and l4 = h 14.83 mm,mm. w4 = The 8.5 mm, ws = 20.4 mm, h3 =fan 19.0beam mm, antenna h2 = 2.0 mm, and 1 hl31 == 6.22 35.0 mm, mm. w The fabricated frequency fan beam antenna array is shown in Figure 4. 3 = 11.52 mm, l4 = 14.83 mm, w4 = 8.5 mm, ws = 20.4 mm, h3 = 19.0 mm, h2 = 2.0 mm, and shown Figure h1 = 35.0inmm. The4.fabricated frequency fan beam antenna array is shown in Figure 4. h1 = 35.0 mm. The fabricated frequency fan beam antenna array is shown in Figure 4.

Figure 3. (a) CPW feed line; (b) Geometrical parameters of the developed single element of the fan Figure Figure 3. 3. (a) (a) CPW CPW feed feed line; line; (b) (b) Geometrical Geometrical parameters parameters of of the the developed developed single single element element of of the the fan fan beam array. Figurearray. 3. (a) CPW feed line; (b) Geometrical parameters of the developed single element of the fan beam beam array. beam array.

Figure 4. Fabricated fan beam array antenna. Figure 4. Fabricated fan beam array antenna. Figure 4. Fabricated fan beam array antenna.

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4. Simulation and Measurements of the Developed Fan Beam Array Antenna 4. Simulation and Measurements of the Developed Fan Beam Array Antenna The fan beam array antenna isofdesigned and fabricated, and the response 4. Simulation and Measurements the Developed Fan Beam Array Antenna is measured as well. The fan beam array antenna is designed and fabricated, and the response is measured well.7 The simulated and measured S-parameter response is shown in Figure 5a. Also, Figures 6asand The fan beam array antenna is designed and fabricated, and the response is measured as well. antenna designed and fabricated, and the response is measured as well. The simulated and measured S-parameter response is shown in Figure 5a. Also, Figures 6 and 7 represents a normalized E-plane radiation pattern of the fan beam antenna array at 3.3 GHz and 3.5 The response is Also, Figures 6 and 7 simulated and measured S-parameter shown in Figure 5a. Also, Figures 6 represents a normalized E-plane pattern the side fan beam antenna at 3.3with GHzthe and 3.5 GHz, respectively. Figures 6 andradiation 7 also shows thatofone lobe is entirelyarray merged main represents aa normalized E-plane radiation pattern ofof the fan beam antenna array at 3.3 GHz and 3.5 normalized E-plane radiation pattern the fan beam antenna array at 3.3 GHz and GHz, respectively. Figures 6 and 7 also shows that one side lobe is entirely merged with the main lobe due to the grounded reflector. It also shows that the back lobe level is considerably reduced by GHz, respectively. Figures 6 and 7 It also shows that side entirely merged with the 3.5 GHz, Figures 6 and 7 also also one sidelobe lobeisis entirely merged with the main lobe due to the grounded reflector. shows thatone the back level is considerably reduced by adding a respectively. grounded reflector as judged from Figure 2. Also, Figure 8 displays the simulated and lobe due to the grounded reflector. It also shows that the back lobe level is considerably reduced by due to the grounded reflector. It also shows that the back lobe level is considerably reduced adding a grounded reflector as judged Figure The 2. Also, Figure 8 displays the antenna simulated measured antenna gain with and withoutfrom a reflector. overall performance of the canand be adding a grounded reflector as as judged from Figure 2.2.Also, Figure 88displays the simulated by adding a grounded reflector judged from Figure Also, Figure displays the simulated measured antenna gain with and without a reflector. The overall performance of the antenna canand be summarized well in Table 2. measured antenna with summarized well ingain Table 2. and without a reflector. The overall performance of the antenna can be summarized well in Table Table 2. 2.

Figure 5. (a) S11 plot of the developed antenna array having fan beam with and without reflector; (b) Figure 5. imaginary (a) S11 plotpart of the developed antenna array input havingimpedance. fan beam with and without reflector; (b) Real and beam array antennas Figure 5. (a) S11 plot of of thefan developed antenna array having fan beam with and without reflector; Figure 5. (a) S11 plot of the developed antenna array having fan beam with and without reflector; (b) Real and imaginary part of fan beam array antennas input impedance. (b) Real and imaginary part of fan beam array antennas input impedance. Real and imaginary part of fan beam array antennas input impedance.

Figure 6. Normalized E-plane pattern of the developed antenna array having fan beam at 3.30 GHz. Figure 6. 6. Normalized Normalized E-plane E-plane pattern pattern of of the the developed developed antenna antenna array array having Figure having fan fan beam beam at at 3.30 3.30 GHz. GHz. Figure 6. Normalized E-plane pattern of the developed antenna array having fan beam at 3.30 GHz.

Figure 7. 7. Normalized Normalized E-plane E-plane pattern pattern of of the the developed developed antenna antenna array array having Figure having fan fan beam beam at at 3.50 3.50 GHz. GHz. Figure 7. Normalized E-plane pattern of the developed antenna array having fan beam at 3.50 GHz. Figure 7. Normalized E-plane pattern of the developed antenna array having fan beam at 3.50 GHz.

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Table 2. Achieved Results of the fan beam array antenna (utilizing reflector and without reflector). Table 2. Achieved Results of the fan beam array antenna (utilizing reflector and without reflector). Freq. Freq.

Without reflector Without reflector With reflector With reflector Beam-width Without reflector Without reflector Beam-width (3 dB) With reflector With reflector (3 dB) Back-lobeWithout reflector Back-lobe-level Without reflector level (Max) With reflector With reflector (Max)

Relative SLL

Relative SLL

3.30 GHz 3.50 GHz 3.50 GHz HFSS Measured HFSS Measured HFSS Measured HFSS Measured Results Results Results Results Results Results Results Results −8.49 dB −9.40 dB −8.49 dB −9.40 dB −8.3 dB −9.1 dB −15.6 dB −15.1 dB −8.3 dB −9.1 dB −15.6 dB −15.1 dB 30.0° × 99.0° 29.0° × 92.5° 30.0◦ × 99.0◦ 29.0◦ × 92.5◦ 28.0° × 90.0° 26° × 79.0° 28.5° × 89.5° 27.0° × 76.0° 28.0◦ × 90.0◦ 26◦ × 79.0◦ 28.5◦ × 89.5◦ 27.0◦ × 76.0◦ 0 dB 0 dB 0 dB 0 dB −9.50 dB −12dBdB dB dB −9.50 dB −12 −−13.95 13.95 dB −−14.4 14.4 dB 3.30 GHz

Figure8.8.Measured Measuredand andSimulated SimulatedGain Gain(dB) (dB)ofofthe thedeveloped developedantenna antennaarray arrayhaving havingfan fanbeam beamwith with Figure and without a reflector. and without a reflector.

Parametric analysis analysis has has been been performed performed toto show show the the critical critical parameters parameters which which affect affect the the Parametric performanceof ofthe theantenna. antenna.The Theheight heightof ofthe thereflector reflectorhh11and anddistance distancebetween betweenlast lastarray arrayelement element performance and filter position l has been simulated for different values as shown in Figure 9. It can be seen from 1 and filter position l1 has been simulated for different values as shown in Figure 9. It can be seen from Figure 9a–c that the by changing l at same value of reflector height changes the antenna response. Figure 9a–c that the by changing l1 at1 same value of reflector height changes the antenna response. So So proper combination h1 and is very important achieve our desiredresponse. response.Also, Also,for forplanar planar proper combination of hof 1 and l1 isl1very important to to achieve our desired type of antenna reflector should be symmetrical for the best performance, so the height of reflector type of antenna reflector should be symmetrical for the best performance, so the height of reflector isis reducedhere hereusing usingthe theconcept conceptof ofimage imagetheory theoryfrom from70.0 70.0 mm mm to to 35.0 35.0 mm. mm. reduced Figure5a 5ademonstrates demonstratesS11 S11parameter parametermagnitude magnitude(dB) (dB)(simulation (simulationresults) results)employing employingAnsoft Ansoft Figure HFSS as well as the measurement results obtained for the proposed antenna and without reflector HFSS as well as the measurement results obtained for the proposed antenna and without reflector antenna.The Themeasured measured input input impedance impedance bandwidth antenna. bandwidth for for VSWR VSWRless lessthan than22isis3250–3700 3250–3700MHz, MHz,which whichis 12.94% fractional band-width for proposed antenna with grounded reflector. In addition, the Figure 5a is 12.94% fractional band-width for proposed antenna with grounded reflector. In addition, the shows that the grounded reflector improves the antenna reflection coefficient, noticeably. In addition, Figure 5a shows that the grounded reflector improves the antenna reflection coefficient, noticeably. this effect was observed previously in Reference [23] when reflector improved input In addition, this effect was observed previously in Reference [23]grounded when grounded reflector improved impedance band width through 1.55–1.75 GHz in part of operating band. The concept of improving input impedance band width through 1.55–1.75 GHz in part of operating band. The concept the of input impedance by grounded in earlyreflector attempt in to early make attempt use of the properties improving the input impedancereflector by grounded tobroad-banding make use of the broadof antennas is dealt in our References [22,23]. The real[22,23]. and imaginary part banding properties ofwith antennas is previous dealt withwork in ourofprevious work of References The real and of proposed antennas input impedance is shown in Figure 5b. This figure is a very clear example, imaginary part of proposed antennas input impedance is shown in Figure 5b. This figure is a very whichexample, shows that a grounded reflector can improve input can antenna impedance as well as clear which shows that a grounded reflector improve input bandwidth antenna impedance radiation pattern characteristics. bandwidth as well as radiation pattern characteristics.

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Figure Figure 9. 9. Parametric Parametric analysis analysis of of the the Critical Critical parameters parameters of the fan beam array antenna; (a) Different l11 Figure 9. Parametric analysis of the Critical parameters of fan beam array antenna; (a) having Different having h1 the =h160 (c) Different l1 values h1 =l1 values values having having hh11==1515mm; mm;(b) (b)Different Differentl1 lvalues having = mm; 60 mm; (c) Different l1 values having 1 values 1 = 15 mm; (b) Different l1 values having h1 = 60 mm; (c) Different l1 values having h1 = values having h 80 h1 mm. = 80 mm. 80 mm.

5. Development Development of of Wideband Wideband Bandpass Bandpass Filter Filter with with Simulated Simulated and and Measured 5. Measured Results Results 5. Development of Wideband Bandpass Filter with Simulated and Measured Results The SCSRR SCSRR based fabricated asas shown in The based miniaturized miniaturizedwideband widebandbandpass bandpassfilter filterisisdesigned designedand and fabricated shown 2 The SCSRR based miniaturized wideband bandpass filter is designed and fabricated as shown Figure 10.10. TheThe dimensions of the substrate are: are: Ws × × 26.0 mmmm while other parameters are: 2 while in Figure dimensions of the substrate WsLs×=Ls17.6 = 17.6 × 26.0 other parameters 2 while other parameters in Figure 10. The dimensions of the substrate are: Ws × Ls = 17.6 × 26.0 mm L = 2.4 mm, W = 0.6 mm, L = 1.55 mm, G = 0.55 mm, L = 1.4 mm, G = 0.25 mm, W = 2.0 mm, 1 L1 = 2.4 mm,1 W1 = 0.6 mm, 2 L2 = 1.55 mm, 2G2 = 0.55 mm, 3L3 = 1.4 mm, G11 = 0.25 mm, Wsq are: sq = 2.0 mm, are: = 2.4 mm, 1 2.0 = 0.6 mm, L2DD =1 11.55 mm, GThis 2This = 0.55 mm, Lthe 3the = 1.4 mm,to Goperate 1operate = 0.25 mm, Wsq =to mm, W =10.2 0.2 mm, mm, and 7.2 mm. filter has ability to at33 GHz GHz to2.0 GHz os =L W os mm, LLsqsqW ==2.0 mm, and ==7.2 mm. filter has ability at 77 GHz W os = 0.2 mm, L sq = 2.0 mm, and D 1 = 7.2 mm. This filter has the ability to operate at 3 GHz to 7 GHz frequency range low isolation. The The simulated and measured frequency response response of the developed frequency rangewith with low isolation. simulated and measured frequency of the frequency range with low isolation. The simulated and measured frequency response ofwell the wideband bandpass filter is shown in Figure 11, which shows that the filter operates from the developed wideband bandpass filter is shown in Figure 11, which shows that the filter well operates developed wideband bandpass filter is shown in Figure 11, which shows that the filter operates well 3 GHz to37.5 GHz range. range. from the GHz to frequency 7.5 GHz frequency from the 3 GHz to 7.5 GHz frequency range.

(a) (a)

(b) (b)

(c) (c)

Figure 10. (a) (a) Schematics Schematics and and geometrical geometrical diagram diagram of of the the SCSRR SCSRR based based bandpass bandpass filter; filter; (b) (b) Back-side Figure Figure 10. (a) Schematics geometrical diagram the SCSRR based bandpass of of theoffabricated bandpass filter. of the fabricated bandpassand filter; (c) Front-side filter. filter; (b) Back-side of the fabricated bandpass filter; (c) Front-side of the fabricated bandpass filter.

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(a) (a)

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(b) (b)

Figure 11. Measured Simulated frequency response of SCSRR based Figure Measured andand Simulated frequency response of the SCSRR miniaturized bandpass Figure11. 11.(a)(a) (a) Measured and Simulated frequency response of the thebased SCSRR based miniaturized miniaturized bandpass filter; (b) Zoom-in of part (a) from 3 GHz to 7.5 GHz. filter; (b) Zoom-in ofZoom-in part (a) from 3 GHz to 7.53 GHz. bandpass filter; (b) of part (a) from GHz to 7.5 GHz.

6. 6.6.Development Development of Bandwidth-Enhanced Frequency Scanning Fan Beam Array Antenna Developmentof ofBandwidth-Enhanced Bandwidth-EnhancedFrequency FrequencyScanning ScanningFan FanBeam BeamArray ArrayAntenna Antenna The frequency scanning fan beam array antenna is developed by The Proposed bandwidth-enhanced frequency scanning fan beam array antenna isisdeveloped TheProposed Proposedbandwidth-enhanced bandwidth-enhanced frequency scanning fan beam array antenna developed integrating the miniaturized wideband bandpass filter with fan beam array antenna in their opposite by by integrating integrating the the miniaturized miniaturized wideband wideband bandpass bandpass filter filter with with fan fan beam beam array array antenna antenna in in their their side of the excitation. The schematic sketch of the proposed antenna with integrated filter is shown opposite side of the excitation. The schematic sketch of the proposed antenna with integrated filter isis opposite side of the excitation. The schematic sketch of the proposed antenna with integrated filterin Figure 12. As can be seen from the Figure 11 that the filter is placed in CPW fed line and matched for shown shownin inFigure Figure12. 12.As Ascan canbe beseen seenfrom fromthe theFigure Figure11 11that thatthe thefilter filterisisplaced placedin inCPW CPWfed fedline lineand and 2.8 GHz to 6 GHz frequency range. This technique is very promising and this type of filter integration matched for 2.8 GHz to 6 GHz frequency range. This technique is very promising and this type matched for 2.8 GHz to 6 GHz frequency range. This technique is very promising and this typeof of within the antennawithin has not yetantenna been reported inyet thebeen literature. The in proposed bandwidth-enhanced filter the has The filter integration integration within the antenna has not not yet been reported reported in the the literature. literature. The proposed proposed frequency scanning fan beam array antenna with integrated bandpass filter is also bandpass fabricated and bandwidth-enhanced frequency scanning fan beam array with integrated isis bandwidth-enhanced frequency scanning fan beam arrayantenna antenna with integrated bandpassfilter filteris shown in Figure 13. also fabricated and is shown in Figure 13. also fabricated and is shown in Figure 13.

Figure 12. Perspective view of the Proposed Bandwidth-Enhanced Frequency Scanning Fan Beam Figure 12. view the Proposed Frequency Figure 12.Perspective Perspective viewof of theintegrated ProposedBandwidth-Enhanced Bandwidth-Enhanced FrequencyScanning ScanningFan FanBeam Beam Array Antenna with bandpass filter into the feedline. Array ArrayAntenna Antennawith withbandpass bandpassfilter filterintegrated integratedinto intothe thefeedline. feedline.

The response of the developed miniaturized bandpass filter is shown in Figure 11, which has a The of miniaturized bandpass filter isisshown in 11, has Theresponse response ofthe thedeveloped developed miniaturized bandpass filter shown inFigure Figure 11, which hasisaa very promising frequency response and can be used as a UWB bandpass filter. The size ofwhich the filter very promising frequency response and can be used as a UWB bandpass filter. The size of the filter verysmall, promising response and canfan be beam used as a UWB bandpass The size ofresponse. the filter very and itfrequency is placed in the developed array antenna havingfilter. a narrowband isis very and itit isis placed in fan array having aa narrowband very small, small, andbandpass placed in the the developed developed fan beam beam array antenna antenna having narrowband Different wideband resonators have been tested for achieving our desired response, but the response. Different wideband bandpass resonators have been tested for achieving our desired response.miniaturized Different wideband bandpass resonators haveresponse been tested for achieving our desired proposed filter provides the most promising and improves matching of the response, but miniaturized filter provides the promising and improves response, butathe theproposed proposed miniaturized filter provides themost most promising response andsmall improves antenna over wide bandwidth as shown in Figure 14. Moreover, the proposedresponse filter is very and matching of the antenna over a wide bandwidth as shown in Figure 14. Moreover, the proposed filter matching of the antenna wide bandwidth shown inthe Figure 14.size. Moreover, the proposed filter has been integrated withinover the aantenna in order toasmaintain circuit isisvery verysmall smalland andhas hasbeen beenintegrated integratedwithin withinthe theantenna antennain inorder orderto tomaintain maintainthe thecircuit circuitsize. size.

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Figure 13. Fabricated Picture of the Bandwidth-Enhanced Frequency Scanning Fan Beam Array Figure 13.13. Fabricated Picture of of thethe Bandwidth-Enhanced Frequency Scanning Fan Beam Array Figure Fabricated Picture Bandwidth-Enhanced Frequency Scanning Fan Beam Array Antenna with bandpass filter integrated into the feedline (a) Perspective view; (b) Top view. Antenna with bandpass filter integrated into the feedline (a) Perspective view; (b) Top view. Antenna with bandpass filter integrated into the feedline (a) Perspective view; (b) Top view.

00 -10 -10 S11 (dB) S11 (dB)

-20 -20 -30 -30 -40 -40

Simulation Simulation Measurement Measurement

-50 -50 3.0 3.0

3.5 3.5

4.04.0 4.54.5 5.0 5.0 Frequency (GHz) Frequency (GHz)

5.5 5.5

6.06.0

Figure 14.14. Simulated and Measured response of of the Bandwidth-Enhanced Frequency Scanning Fan Figure Simulated and Measured response the Bandwidth-Enhanced Frequency Scanning Fan Figure 14. Simulated and Measured response of the Bandwidth-Enhanced Frequency Scanning Fan Beam Array Antenna with anan integrated bandpass filter. Beam Array Antenna with integrated bandpass filter. Beam Array Antenna with an integrated bandpass filter.

7. Simulation and Measurement of the Proposed Antenna 7. 7. Simulation and Measurement ofof the Proposed Antenna Simulation and Measurement the Proposed Antenna The simulated and measured frequency response of theofproposed bandwidth-enhanced frequency The Thesimulated simulatedand andmeasured measuredfrequency frequencyresponse response ofthe theproposed proposedbandwidth-enhanced bandwidth-enhanced scanning fan beam array antenna integrated with miniaturized wideband bandpass filter is filter shown frequency scanning fan beam array antenna integrated with miniaturized wideband bandpass frequency scanning fan beam array antenna integrated with miniaturized wideband bandpass filter in Figure 14. It clearly shows that the bandwidth of the fan beam array antenna is considerably is is shown shownininFigure Figure14.14.It Itclearly clearlyshows showsthat thatthe thebandwidth bandwidthofofthe thefan fanbeam beamarray arrayantenna antennais is increased by placing by theplacing bandpass filter in the feedline. It can beIt seen from Figure 5 that 5the fan considerably increased the bandpass filter inin the feedline. can be seen from Figure considerably increased by placing the bandpass filter the feedline. It can be seen from Figure that 5 that beam array antenna without integrated bandpass filter operate up to 3.8 GHz, while by integrating the thefan fanbeam beamarray arrayantenna antennawithout withoutintegrated integratedbandpass bandpassfilter filteroperate operateupuptoto3.83.8GHz, GHz,while whilebyby the filter, the bandwidth is enhanced and the proposed antenna operates from the 2.8 GHz to 6 2.8 GHz integrating the filter, the bandwidth is is enhanced and the proposed antenna operates from the integrating the filter, the bandwidth enhanced and the proposed antenna operates from the 2.8 GHz to 6 GHz frequency range. The equivalent circuit model of the proposed bandwidth-enhanced GHz to 6 GHz frequency range. The equivalent circuit model of the proposed bandwidth-enhanced

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frequency scanning fan beam array antenna integrated with miniaturized wideband bandpass filter frequency TheSome equivalent the proposed frequency is shown in range. Figure 15. requiredcircuit valuesmodel for theofequivalent circuitbandwidth-enhanced model are calculated and listed scanning fan beam array antenna integrated with miniaturized wideband bandpass filter is shown in in Table 3. The equivalent circuit of the filter part is simulated in AWR and compared with the Figure 15. Some required forthat the equivalent circuit model are calculated simulation from HFSS andvalues it is seen the equivalent circuit response is almostand the listed same in as Table shown3. The equivalent circuit of the filter part is simulated in AWR and compared with the simulation from in Figure 16. HFSS and it is seen that the equivalent circuit response is almost the same as shown in Figure 16. Table 3. Required values for the equivalent circuit model. Table 3. Required values for the equivalent circuit model.

Type

Type Zom

Zsq Zom ZsqZos ZosZos Zos n n

Value Frequency 50 Value Ω - Frequency 179 50 Ω Ω 9.25 GHz 9.25 GHz 78.5179 Ω Ω 8.5 GHz 8.5 GHz 75.778.5 Ω Ω 6.0 GHz 75.7 Ω 6.0 GHz Z√ om / Z os Zom /Zos

-

Figure 15. Equivalent circuit model developed for the filter and antenna. Figure 15. Equivalent circuit model developed for the filter and antenna.

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Figure 16. Frequency response comparison between HFSS and AWR for filter equivalent circuit validation. Figure Frequencyresponse responsecomparison comparison between between HFSS filter equivalent circuit validation. Figure 16.16. Frequency HFSSand andAWR AWRfor for filter equivalent circuit validation.

The frequency frequency scanning scanning of of the the proposed proposed antenna antenna with with integrated integrated bandpass bandpass filter filter from from 2.8 2.8 GHz GHz The The frequency scanning of the proposed antenna with integrated bandpass filter from 2.8 GHz to 6 GHz is displayed in Figure 17. It is clear that a wide frequency scanning is achieved from 50 to to is 17. ItIt isisclear clearthat thataawide widefrequency frequencyscanning scanningisisachieved achievedfrom from5050 to66GHz GHz is displayed displayed in in Figure Figure 17. to ◦ 125125 degrees due to the grounded reflector.The Thegrounded groundedreflector reflectorgreatly greatlyreduces reducesthe theback backlobes lobes as as to C due to the grounded reflector. 125 degrees due to the grounded reflector. The grounded reflector greatly reduces the back lobes as shown in in Figure 16. It is seen GHz thethe main beam is atis50 whileatat66GHz GHz the main main shown seenthat thatat at2.8 2.8 GHz main beam at degrees 50 ◦ C while shown in Figure Figure 16. 16. ItIt isisseen that at 2.8 GHz the main beam is at 50 degrees while at 6 GHzthe the main ◦ beam is shifted to almost 125 degrees. This behavior makes the antenna additionally advantageous beam This behavior makes the antenna additionally advantageous for use beamisisshifted shiftedtotoalmost almost125 125C. degrees. This behavior makes the antenna additionally advantageous for use in OFDM-UWB communication applications. The percentage radiation efficiency of the in communication applications. The percentage radiation efficiency the proposed forOFDM-UWB use in OFDM-UWB communication applications. The percentage radiation of efficiency of the proposed developed frequency scanning fan beam array antenna with an integrated bandpass filter developed frequency scanning beam array antenna with an integrated bandpass filter is shown proposed developed frequencyfan scanning fan beam array antenna with an integrated bandpass filter is shown in The percentage radiation efficiency the proposed antenna is within range in 18.Figure The 18. percentage radiation efficiency of the of proposed antenna is within the the range of is Figure shown in Figure 18. The percentage radiation efficiency of the proposed antenna is within the range of approximately 60% to 92% within the passband. The radiation efficiency shows the bandpass filter approximately 60% to 92% within thethe passband. The radiation of approximately 60% to 92% within passband. The radiationefficiency efficiencyshows showsthe thebandpass bandpassfilter filter effect for for antenna antenna input input impedance impedancematch. match. effect effect for antenna input impedance match.

Figure Figure 17. 17. Normalized Normalized radiation radiation pattern pattern of of the the proposed proposed developed developed frequency frequency scanning scanning fan fan beam beam Figure 17. Normalized radiationbandpass pattern of the proposed developed frequency scanning fan beam array antenna with an integrated filter. array antenna with an integrated bandpass filter. array antenna with an integrated bandpass filter.

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Figure Figure18.18.Percentage Percentageradiation radiationefficiency efficiencyofofthe theproposed proposeddeveloped developedfrequency frequencyscanning scanningfan fanbeam beam Figure 18. Percentage radiation efficiency offilter. the proposed developed frequency scanning fan beam array with anan integrated bandpass filter. arrayantenna antenna with integrated bandpass array antenna with an integrated bandpass filter.

8.8.Application Detection ApplicationininRobotics Roboticsfor forTarget Target Detection 8. Application in Robotics for Target Detection The proposed frequency scanning antenna can can be beused usedforfortarget target detection in Robotics. The proposed frequency scanning antenna detection in Robotics. The The scanning operation for target location with can physical movement candetection be performed as single The proposed frequency scanning antenna be used for Robotics. The scanning operation for target location with physical movement cantarget be performed as in single sided here. sided here.achieved It is also achieved that if the proposed antenna is fed from two ends at same scanning operation for target location with physical movement can be performed as single sided here. It is also that if the proposed antenna is fed from two opposite endsopposite at same frequency, two frequency, two counter scanning beams can be achieved. Due to this property of the proposed scanning Itcounter is also achieved that if the proposed antenna is fed from two opposite ends at same frequency, two scanning beams can be achieved. Due to this property of the proposed scanning antenna, it antenna, it can be turned around thecenter, physical center, and we can establish angle target mechanism detectionit counter scanning beams can be achieved. Due thiscan property of the proposed scanning antenna, can be turned around the physical andto we establish angle target detection mechanism easily. The object can be easily tracked from received power against the turn angle by can be turned around theeasily physical center, we can establish angle detection mechanism easily. The object can be tracked fromand received power against thetarget turn angle by null pointing. null pointing. easily. The object be easily received power against the turn angle by nullfor pointing. Based on thecan above idea, tracked we havefrom implemented the proposed antenna in Robotics pipeline Based on the above idea, we have implemented the proposed antenna in Robotics for pipeline Baseddetection. on the above we have implemented the directions proposed antenna in at Robotics forend pipeline blockage Two idea, antennas excited from opposite are placed the open of the blockage detection. Two antennas excited from opposite directions are placed at the open end of the blockage detection. Two antennas excited from opposite directions are placed at the open end of the C-arm of the robot, designed for pipeline as shown in Figure 19a. We placed one antenna at the upper C-arm of the robot, designed for pipeline as shown in Figure 19a. We placed one antenna at the upper C-arm of the robot, designed for pipeline as shown in Figure 19a. We placed one antenna at the upper arm and another one at the lower arm of the robot. Excitation current is applied at the upper arm, arm and one of robot. Excitation current isisapplied the arm, arm and another oneat atthe the lowerarm arm ofthe the robot. Excitation current applied at theupper upper arm, which isanother 180 degrees out oflower phase to that of the lower arm’s applied current. So, ifat there is any target which is 180 degrees out of phase to that of the lower arm’s applied current. So, if there is any target which is 180 degrees out of phase to that of the lower arm’s applied current. So, if there is any target between the two excited antennas at the same frequency, there will be a two counter scanning beams between the excited atatthe same frequency, there be beams between the two excited antennas the same frequency, therewill willtarget beaatwo two counter scanning beams as shown intwo Figure 19b.antennas This is the easiest way of detecting the andcounter it will scanning pave the way for as shown in Figure 19b. This is the easiest way of detecting the target and it will pave the way as shown in Figure 19b. Thisantennas is the easiest waydetection of detecting the target and it will pave the wayfor for future research of scanning for target in different industrial fields. future futureresearch researchofofscanning scanningantennas antennasfor fortarget targetdetection detectioninindifferent differentindustrial industrialfields. fields.

Figure 19. (a) C-arms of the robot where both antennas is placed; (b) Simulated normalized radiation Figure 19. C-arms of robot where both antennas isisplaced; (b) Simulated radiation Figure 19. (a) C-arms ofthe the robot wherein both antennas placed; (b)of Simulated normalized radiation pattern of(a) two antennas when excited opposite direction in case target at normalized freq. of 4 GHz. pattern of two antennas when excited in opposite direction in case of target at freq. of 4 GHz. pattern of two antennas when excited in opposite direction in case of target at freq. of 4 GHz.

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9. Conclusions In this paper, we presented the bandwidth-enhanced and frequency scanning for developed fan beam array antenna utilizing novel technique of band-pass filter integration. First, a fan beam array antenna utilizing a grounded coplanar waveguide (GCPW) radiating element, CPW feed line, and the grounded reflector is developed for WiMAX applications. Secondly, a miniaturized wide-band bandpass filter is developed using SCSRR (Semi-Complementary Split Ring Resonator) and DGS (Defective Ground Structures) operating at the 3–8 GHz frequency band. Finally, the designed filter is integrated within the frequency scanning beam array antenna in a novel way to increase the impedance bandwidth as well as frequency scanning. The new frequency beam array antenna with integrated band-pass filter operates at 2.8 GHz to 6 GHz with a wide frequency scanning from the 50 to 125 ◦ C range. Author Contributions: The paper is developed in contribution of all authors including simulation, designing, fabrication, measurement, application and validation. Funding: This work is partially supported by the Qatar National Research Fund (QNRF) grant number (NPRP No.: 7-1045-2-395) for authors (S.S.M). The authors would like to thanks Health technology incubator of Jahrom University of Medical Sciences for their valuable helps during this project. Conflicts of Interest: The authors declare no conflict of interest.

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