This paper presents the investigation based upon the resonant circuit approach to characterize the rectangular

microstrip patch antenna from the low-pass prototype lumped

element. The physical layout of the rectangular microstrip patch antenna based on single-mode and dual-mode will be established. An improvement on bandwidth of the antenna can be achieved by increasing the number of modes. In the paper, the understanding of microwave filter synthesis technique is applied in order to obtain the resonance at 2 GHz. A notch technique is used in the design to produce dual-mode frequencies on the microstrip patch antenna. The prototype circuit and proposed physical layout of the single and dual-mode microstrip patch antennas are demonstrated through the analysis of circuit and EM simulations in order to proof the proposed concept. This

study would be useful to realize antenna for broadband applications as well as to investigate the appropriate technique

for integrating antenna and microwave filter

Abd Aziz, Mohamad Zoinol Abidin

Meor Said, Maizatul Alice

Sam, Weng Yik

Zakaria, Zahriladha

English

Universiti Teknikal Malaysia Melaka (UTeM) Repository

(b) (a) Rectangular Microstrip Patch Antenna Based on Resonant Circuit Approach  Z. Zakaria, W. Y. Sam, M. Z. A. Abd Aziz and M. A. Meor Said Centre for Telecommunication Research and Innovation (CeTRI), Department of Telecommunication Engineering Faculty of Electronic and Computer Engineering, Universiti Teknikal Malaysia Melaka (UTeM)  Hang Tuah Jaya 76100 Melaka, Malaysia.  E-mail: zahriladha@utem.edu.my, samwengyik2@hotmail.com, mohamadzoinol@utem.edu.my, maizatul@utem.edu.my  Abstract—This paper presents the investigation based upon the resonant circuit approach to characterize the rectangular microstrip patch antenna from the low-pass prototype lumped element. The physical layout of the rectangular microstrip patch antenna based on single-mode and dual-mode will be established. An improvement on bandwidth of the antenna can be achieved by increasing the number of modes. In the paper, the understanding of microwave filter synthesis technique is applied in order to obtain the resonance at 2 GHz. A notch technique is used in the design to produce dual-mode frequencies on the microstrip patch antenna. The prototype circuit and proposed physical layout of the single and dual-mode microstrip patch antennas are demonstrated through the analysis of circuit and EM simulations in order to proof the proposed concept. This study would be useful to realize antenna for broadband applications as well as to investigate the appropriate technique for integrating antenna and microwave filter.  Keywords-Rectangular microstrip patch antenna; Single-mode Antenna; Dual-mode Antenna; Microwave Filter. I. INTRODUCTION The rapid development of wireless applications ranging from Bluetooth, WLANs, GSM, LTE, satellite and military applications requires more efficient, low profile and flexible antennas. Microstrip patch antennas are generally used in communication systems for their benefit of ease of fabrication, low profile, lighter in weight and low cost [1]. However, there is a limitation on its performance for a microstrip patch antenna in term of narrow bandwidth [1][2]. The most well-known method was proposed to overcome the limitation is by increasing the height of the substrate [3]. However, this method increases the complexity and suffers from the power loss. In [4], the antenna was designed with modified circle-like slot was used on the elements. However, etching two L-shaped slots on the ground are slightly complex to design on the antenna especially come to 50 Ω impedance matching. In this paper, a development of the rectangular microstrip patch antenna based on microwave filter circuit theory is presented. The rectangular microstrip patch antennas are designed at resonant frequency of 2 GHz for single and dual-mode. The advantages of this technique are the realization of microstrip patch antenna that can be transformed for broadband applications and also can be applied to the integration technique between antenna and microwave filter. II. EQUIVALENT CIRCUIT DESIGN In this section, a low-pass filter prototype equivalent circuit is used to produce single-mode antenna equivalent circuit as shown in Fig. 1. The inverter, K01 represents the coupling mechanism between the input port and the resonance circuit [5]. In Fig 2 (a) shows the equivalent circuit of single-mode based on the low-pass prototype circuit shown in Fig. 1. Similarly the dual-mode antenna equivalent circuit as shown in Fig. 2 (b) can be developed based on the second order of the low-pass prototype circuit. The dual-mode antenna equivalent circuit can also be developed based on a combination of two single-mode equivalent circuit.   Figure 1.  Low-pass equivalent circuit of rectangular microstrip patch antenna    Figure 2.  (a) Single-mode circuit of the rectangular microstrip patch antenna (b) Dual-mode circuit of the rectangular microstrip patch antenna The impedance inverter Kr, r+1 and the capacitance Cr value of the low-pass prototype can be determined using [6]:                                      ܥ௥ ൌ ଶఎ sin ቂሺଶ௥ିଵሻగଶே ቃ                            (1)                              ܭ௥,௥ାଵ ൌ  ൣఎమା௦௜௡మሺ௥గ/ேሻ൧భ/మఎ                         (2) 2012 IEEE Symposium on Wireless Technology and Applications (ISWTA), September 23-26, 2012, Bandung, Indonesia978-1-4673-2210-2/12/$31.00 ©2012 IEEE 220where N, is the number of order of the ndefined as [6]:                                ߟ ൌ ݏ݄݅݊ ቂଵே ݏ݄݅݊ିଵ ቀଵఢቁቃ  while ߳ is the ripple of insertion loss. The acircuit can be transformed from the loequivalent circuit using [6]:                                          ܮᇱ௥ ൌ  ଵఈ஼ೝఠ೚                                                      ܥᇱ௥ ൌ ఈ஼ೝఠబ              where ߱௢  is the geometric midband freqbandwidth scaling factor and the r is the numresistances, R acts as load of the prototype ciIII. RECTANGULAR MICROSTRIP PATThe transformation from the antenna eqphysical realization is implemented umicrostrip patch antenna technology. The drectangular microstrip patch antenna can dwidth, w, and the length, L, as shown in Fig.                                  ݓ ൌ  ௖ଶ௙೎ ටଶఌೝାଵ                                             ܮ ൌ ଵଶ௙೎ඥఌ೐೑೑√ఓೝఌೝ       where ௖݂  is center frequency and ߝ௘௙௙permeability. ΔL extended incremental lengtbe calculated using the equation below [7]:                              ∆௅௛ ൌ 0.412൫ఌ೐೑೑ା଴.ଷ൯ቀೢ೓ା଴.ଶሺఌ೐೑೑ି଴.ଶହ଼ሻቀೢ೓ା଴h is the thickness of the dielectric substracalculated using this formula [7]:                                  ݕ௢ ൌ ௅గ ܿ݋ݏିଵ ቂଵହ଴ோ ቃଵ/ଶ    Figure 3.  Top view rectangular microstrip pwhere R is the impedance and ݕ௢  is the ishown in Fig. 3. The dual-mode frequenetwork and η, is                        (3) ntenna equivalent w-pass prototype                         (4)                         (5) uency; ߙ  is the ber of order. The rcuit. CH ANTENNA uivalent circuit to sing rectangular imensions of the etermined by the 3, using [7]:                         (6)                         (7)  is the efficient h of the patch can ଺ସቁ.଼ቁ          (8) te and ݕ௢  can be                         (9)  atch antenna nset feed line as cy of rectangular microstrip patch antenna is renotch concept that will be explaIV. SIMULAA. Single mode In this section, the single-mhas been designed at 2 GHz usthe coupling value, K01 of 50, inductance, C’ = 63.98 pH. Fig. 4 shows the simulated rcircuit. It shows that the returndB and a -10 dB bandwidth achieved.  Figure 4.  Simulation results of equimThe antenna equivalent circubeen simulated using AdvancCST Microwave Studio in oconcept. The device is construdielectric substrate thick with The thickness of copper is 0.00.019. The dimension of theantenna can be determined usinlength, L, and width, w, of the 48.79 mm respectively. The anwith 50 Ω feed line.  Fig. 5 shows the effect ovarying the length, L, of the miEM simulations using CST. 32.7184 mm gives good reresonance of 2 GHz. This iindicates that at 2 GHz the rewith a -10 dB bandwidth approobtained. alized by simply introducing a ined in next section. TION RESULTS ode antenna equivalent circuit ing equations (1) – (5) to obtain capacitance, L’ = 98.98 pF and esults of the antenna equivalent  loss, S11, with better than -30 of around 31 MHz have been  valent ideal circuit antenna for single-ode it and the physical layout have ed Design System (ADS) and rder to validate the proposed cted using FR-4 on a 1.6 mm permeability constant ߝ௥  = 4.6. 35 mm and the loss tangent is  rectangular microstrip patch g equations (6) – (9). Thus, the patch antenna are 32.4 mm and tenna is connected to input port n the resonant frequency by crostrip patch antenna based on It shows that the length of sponse on the return loss at s summarized in Table I. It turn loss has achieved -30 dB ximately of 39.9 MHz has been 2012 IEEE Symposium on Wireless Technology and Applications (ISWTA), September 23-26, 2012, Bandung, Indonesia221Figure 5.  EM Simulation results of microstrip patch anTABLE I. SIMULATION RESULTS FOR SINGLE-MMICROSTRIP PATCH ANTENNA Frequency (GHz) Return loss (dB) Length, L(mm) 1.937 -19.12 34.2184 1.958 -21.38 33.7184 1.987 -25.05 33.2184 2.000 -29.16 32.7184  B. Dual mode Similarly for the dual-mode and using eqthe antenna equivalent circuit can be designcoupling values, K01 of 50, and K12 of 55capacitance, C1’ = C2’ = 42.436 pF and indu149.225 pH. Fig. 6 shows the simulated resuequivalent circuit. It shows that the return lothan -12 dB and a -10 dB bandwidth of aroubeen achieved. The antenna equivalent circuit and the phbeen simulated using Advanced Design SyCST Microwave Studio in order to validconcept. The device is constructed using Fdielectric substrate thick with permeabilityThe thickness of copper is 0.035mm and t0.019. The dimension of the rectangular antenna can be determined using equations (length, L, and width, w, of the patch antenna70.6 mm respectively. The antenna is connewith 50 Ω feed line. The size of the notch tomode response is 18 mm x 2 mm is showfound that antenna having an appropriaresonates at two different frequencies but won the bandwidth as shown in Fig. 8. -40-35-30-25-20-15-10-501.6 2.0S11 (dB)Frequency (GHz)  tenna for single-mode ODE RECTANGULAR  Bandwidth (MHz) 37.14 38.57 40.19 39.90 uations (1) – (5), ed at 2 GHz with .2765, while the ctance, L1’ = L2’ = lts of the antenna ss, S11 with better nd 82 MHz have ysical layout have stem (ADS) and ate the proposed R-4 on a 1.6mm  constant εr =4.6. he loss tangent is microstrip patch 6) – (9). Thus, the  are 30.5 mm and cted to input port  produce a dual - n in Fig. 7. It is te size of notch ith improvement Fig. 8 shows the effect ovarying the length, L, of the miEM simulations using CST. It smm gives a good response to th1.988 GHz and 2.023 GHz resthe variations of length, L, withcenter frequency of 2 GHz, the-23 dB and a -10dB bandwidthave been obtained. Figure 6.  Simulation results of equmFigure 7.  The physical layer of micdual-Figure 8.  EM Simulation results of m2.4L = 32.7184 mmL = 33.2184 mmL = 33.7184 mmL = 34.2184 mm-35-30-25-20-15-10-501.5S11 (dB)Freqn the resonant frequency by crostrip patch antenna based on hows that the length, L, of 30.5 e return loss and resonances at pectively. Table II summarizes  its response. It indicates that at  return loss, S11 with better than h approximately of 76.87 MHz  ivalent ideal circuit antenna for dual-ode  rostrip patch antenna with a notch for mode  icrostrip patch antenna for dual-mode 2 2.5uency (GHz)L = 30.5mmL = 30.6mmL = 30.7mmL = 30.8mm2012 IEEE Symposium on Wireless Technology and Applications (ISWTA), September 23-26, 2012, Bandung, Indonesia222TABLE II.     SIMULATION RESULTS FOR DUAL-MODE RECTANGULAR MICROSTRIP PATCH ANTENNA Dual-Frequency (GHz) Return loss (dB) Length, L (mm) Bandwidth (MHz) 1.988 & 2.023 -44.25 & -31.60 30.5 76.87 1.989 & 2.018 -27.23 & -42.01 30.6 73.24 1.990 & 2.012 -21.81 & -26.65 30.7 69.03 1.989 & 2.008 -18.04 & -21.41 30.8 64.53 Fig. 9 shows the radiation pattern for the single-mode antenna at 2 GHz. The pattern represents the main lobe magnitude of 4.9 dB at 2.0 degree direction from the origin point. While Fig. 10 shows the radiation pattern for the dual-mode antenna at the resonance of 2 GHz. The main lobe magnitude of 4.7 dB at 1.0 degree direction from the origin point can be observed.  Figure 9.  Simulated radiation pattern for single-mode at frequency 2 GHz  Figure 10.  Simulated radiation pattern for dual-mode at center frequency 2.003 GHz The comparison between single- and dual-mode antennas can be seen in Table III. It shows that the bandwidth of the microstrip patch antenna can be improved through dual-mode response. However further analysis and investigation on the fabrication of the single- and dual-mode antennas need to be carried out in future works. TABLE III.     COMPARISON RESULTS BETWEEN SINGLE-MODE AND DUAL-MODE FOR RECTANGULAR MICROSTRIP PATCH ANTENNA Single-Mode Dual-mode Prototype Circuit Physical layout Prototype Circuit Physical layout Center Frequency (GHz) 2.000 2.000 2.000 2.000 Return loss (dB) -79.53 -29.16 - 12.1 - 23.5 -10 dB Bandwidth (MHz) 31 39.9 76.87 76.87 V. CONCLUSION A new technique to produce dual-mode rectangular microstrip patch antenna based on resonant circuit approach has been developed. The EM simulated results show good agreements with the ideal circuit. The main advantage of this technique is the antenna can be systematically designed to improve the bandwidth of the response. This study is also useful for the design of broadband antenna applications as well as to realize integration between the antenna and microwave filter in a single device. ACKNOWLEDGMENT W. Y. Sam would like to thank UTeM and MyBrain15 program for sponsoring his study. REFERENCES [1] Vishwakarma, R.K.; Kumar, R.; ,"Rectangular notch microstrip antenna for dual-band operation," Recent Advances in Microwave Theory and Applications, 2008 International Conference on Microwave, pp.675-677, 21-24 Nov. 2008. [2] Chew, W.C.; Liu, Q.; , "Resonance frequency of a rectangular microstrip patch," IEEE Transactions on Antennas and Propagation, vol.36, no.8, pp.1045-1056, Aug 1988. [3] Dubey, M.; Bharadwaj, D.; Saini, J.S.; Saxena, V.K.; Jain, R.; Bhatnagar, D.; , "Dual frequency rectangular patch antenna with a rectangular notch for improved bandwidth performance," Recent Advances in Microwave Theory and Applications, 2008 International Conference on Microwave., pp.809-811, 21-24 Nov. 2008. [4] Emadian, R.; Mirmozafari, M.; Ghobadi, C.; Nourinia, J.; , "Bandwidth enhancement of dual band-notched circle-like slot antenna," Electronics Letters , vol.48, no.7, pp.356-357, March 29 2012. [5] Abunjaileh, A.I.; Hunter, I.C.; Kemp, A.H.; , "Application of dual-mode filter techniques to the broadband matching of microstrip patch antennas," Microwaves, Antennas & Propagation, IET , vol.1, no.2, pp.273-276, April 2007. [6] Ian Hunter, Theory and Design of Microwave Filters, The Institution of Electrical Engineers, 2001. [7] C. A. Balanis, Antenna Theory: Analysis and Design, 3rd edition, Wiley, 2005. 2012 IEEE Symposium on Wireless Technology and Applications (ISWTA), September 23-26, 2012, Bandung, Indonesia223

Rectangular Microstrip Patch Antenna Based on

Resonant Circuit Approach

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Rectangular Microstrip Patch Antenna Based on Resonant Circuit Approach

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