UWB Excitation Pulse for Rectangular Patch Antenna

International Journal of Sciences and echniques of Automatic control & comuter engineering IJ-SA, Volume 1, N, Secial Issue ESA, July 16, 13 18. UWB Excitation Pulse for Rectangular Patch Antenna Houda Werfelli, Mondher Chaoui, Mongi Lahiani and Hamadi Ghariani Laboratory of Electronics and echnology of Information (LEI) National Engineers school of Sfax Sfax, unisia werfelli.houda@yahoo.fr Abstract A design rocess of excitation ulse for rectangular atch antenna is resented. he Ultra Wide Band ulse generator is based on multilying the triangular ulse enveloe to a sinusoidal wave in order to generate the nanosecond ulse. his new ulse shae, having maximum amlitude of 154 mv, ulse duration about 1 ns and the ulse reetition eriod PRP is 1 ns, is ex- cited the rectangular atch antenna in the frequency range of 3.1 GHz to 5.1 GHz. he roosed antenna has been devise using Glass Eoxy substrate (FR4) with dielectric constant є r 4.4 and loss tangent tan δ equal to.. he excitation and radiation ulse for UWB rectangular atch antenna is characterized by the bandwidth of GHz, centered at frequency of 4.1 GHz, and the limited Power Sectral Density (PSD) is -41.3 dbm/mhz. Index erms Ultra Wide Band (UWB), ulse, transmitter, generator, multilier, triangular ulse generator, antenna, microstri, rectangular atch, return loss, ADS momentum. A I. INRODUCION ccording to Federal Communication Commission (FCC), Ultra Wide Band communication system is defined as any system that has a bandwidth larger than 5 MHz at - 1dB. he FCC regulation also fixed the maximum average equivalent radiated isotroic Power Sectral Density (PSD) of 41.3dBm /MHz [1]. he radar system can be exloited in a variety and great number of various alications such as military field, detection and localization of the moving object. In later years, the radar is used for non contact measuring of some organs of arameters target such as heart motion and resiration []. Figure 1 makes the synotic of UWB medical radar resenting the most imortant comonents: UWB generator sends a short duration ulse to moving in the direction of target and then detecting the reflected ulse resonse with a UWB receiver [3]. We can identify various shaes of UWB ulses generated: rectangular ulse, raised- cosine ulse and the seudo-raised cosine that can be classified into two large grous. Fig.1. Block diagram of UWB radar One category includes a ulse generated without requiring frequency translation. he ulse width is defined by delay elements that are tunable. he UWB signal generated by such transmitter is tyically referred to as carrier-free imulse or mono-ulse UWB signal [4]. he other category resented a ulse generated at base band and u-convert by frequency translation using a local oscillator. In such transmitters, the bandwidth and center frequency of the generated signal can be adjusted searately by the width and the frequency of the inut oscillator signal [5]. Also, by tuning the center frequency of the oscillator, the transmitter can oerate over multile frequency bands [6] [7]. In the UWB radar system, an antenna is designed to emitting a short signal and receiving echo carrying information to be rocessed. here are several shaes of microstri atch antenna: circular, square radiating element, triangular, semicircular..., but the most common is rectangular element [8] [9]. In this aer, we begin first with a general architecture of the Ultra Wide Band generator. After, we study the design of some blocks of UWB generator. hen, we interested in the his aer was recommended for ublication in revised form by the Editor Staff. Edition: CPU of unis, unisia, ISSN: 1737-7749

UWB Excitation Pulse for Rectangular Patch Antenna H. WERFELLI, M. CHAOUI, M. LAHIANI and H. GHARIANI 14 design and simulation of the rectangular atch antenna. Finally, the various simulation results of this circuit and conclusions are made. f f H f L (3) II. SUDY OF UWB RANSMIER In the literature, there are different ulse shaes for UWB transmitter such as gaussian ulse and its derivatives, triangular, rectangular, and cosine enveloe. he new ulses are generated by converting the triangular enveloe to the 4.1 GHz center frequency via a multilier. he descrition and design for UWB generator circuit is resented in Fig.. A theoretical study of UWB ulse generated and its PSD are resented in this section. he ulse shae is characterized by some arameters, such as the eriod reetition ulse PRP, ulse durations ( ), the bandwidth (B) and the maximum amlitude (V ) [1] [11]. By multilying the outut sine wave of oscillator and triangular ulse, the multilier generates an imulse signal (V OU (t)) whose shae is defined by the following exression: V OU t ( t ) V sin( Π f t) (4) o calculate the distance (D) between radar and obstacle, the time delay ( t) between emission and recetion is measured. his time delay is exressed by the following equation: C t (5) D Where C: seed of light (3.1 8 m/sec). For a short distance (D1 m), ulse should be able to move and return in 6.6 ns. According to equation (5), we deduced the value of eriod reetition ulse PRP1 ns. he maximum imulse amlitude can be calculated as a function of R, PRP and FCC limit values (Γ). he maximum amlitude (V ) of the UWB signal is calculated by the following exression: V Γ 9 1. R. PRP.1 Π (6) Fig.. Proosed architecture of UWB generator In this section, we are interested to study the three blocks of UWB transmitter: oscillator generated a sine wave at frequency 4.1GHz, ulse triangle and multilier. he outut sine wave of oscillator circuit (V (t)) is given by this exression: V (t) V cos (π f t) (1) Where, V and f are the amlitude and the frequency of outut signal resectively. yically, the center frequency f is set equal to 4.1 GHz and the eriod is 44 s. he triangular ulse generator roduces the signal (V 1 (t)) defined by the following exression: V 1 ( t) t 1 ; t ; otherwise t () Where R is the imedance of antenna (R5 ohm) and the maximum of the ower sectral density of the FCC mask limit (Γ 41.3 dbm/mhz). In this research, the arameters of UWB signal are bandwidth B GHz, f 4.1 GHz, maximum amlitude is.154 V, ulse duration 1 ns and eriod reetition ulse PRP1 ns. III. SIMULAION RESULS OF UWB PULSES GENERAOR he roosed architecture of UWB generator deicted in Fig.3 has been designed and simulated using the tool of modeling Agilent Advanced. he duration of triangle enveloe ( 1 ns) is secified by this exression:

15 IJ-SA, Volume 1, N, Secial Issue ESA, July 16. Fig.5. Outut signal of UWB generator he PSD of the UWB ulse generated is shown in Fig.6. he maximum PSD is equal to -41.3 dbm/ MHz and the band width is GHz. From the sectral shae, it is clear that, the outut imulse generated comlies with FCC mask with high sectral iciency. -4-6 m1 m1 freq 4.1GHz dbm(vsecran1)-4.1e1-8 -1 Fig.3. UWB generator model Figure 4 illustrates the outut signals of oscillator (1) and the triangular ulse (). he oscillator circuit generates a signal at 4.1 GHz with amlitude about 154 mv. he triangular signal roduced a ulse of 1 ns duration and the ulse reetition eriod of 1 ns which satisfy the required arameters of our UWB generator architecture. 1, mv, V 1-1 - 1..5-1 -14 4 6 8 1 freq, GHz Fig.6. Pulse PSD in comliance FCC Mask IV. MICROSRIP ANENNA FOR UWB COMMUNICAIONS his section describes the design and analysis of a rectangular microstri atch antenna for UWB alication (Fig.7). he microstri antenna is designed using electromagnetism ADS Momentum with various secifications such as a resonant frequency equal to 4.1 GHz, frequency range [3.1-5.1] GHz, dielectric of Glass Eoxy substrate (FR4) εε rr 4.4, height of substrate h 1.6 mm, loss tangent. [1].. 1 3 4 5 6 7 8 9 1 11 1 13 14 15 time, nsec Fig.4. Inut signals of UWB generator he outut signal of generator (3) is illustrated in Fig.5. he amlitude of the outut signal generator is 76 mv, the ulse width is 1 ns and the ulse reetition eriod is 1 ns. Fig.7. Microstri atch antenna Before designing a rectangular atch antenna, there are several arameters needed to be considered which will affect the antenna bandwidth as well as the resonant frequency. he length (L) and the width (W) are essential arameters of the rectangular atch antenna which calculated by the following exressions [13] [14]: L L L (7) W C f r ε r + 1 (8) Where: C: Velocity of light, 3*1 8 m/s;

UWB Excitation Pulse for Rectangular Patch Antenna H. WERFELLI, M. CHAOUI, M. LAHIANI and H. GHARIANI 16 ε r : Dielectric constant of the substrate; f r : Resonant frequency; L : Effective length; ΔL: Extended length; he ective length, ective dielectric constant and extended length of the microstri antenna are calculated using the following equations: ε L L h *.41 C fr ε (9) ε r + 1 ε r 1 + * ( ε +.3) 1 h 1+ W W +.64 h W ( ε.58) +.8 h (1) (11) Mag. [db] -5-1 S11-15 4 6 Frequency Fig.9. Return loss (S11) Figure 1 shows the simulated result of Voltage Standing Wave Ratio (VSWR) which varies generally from 1.5 to. Starting at simulated result, the rectangular atch antenna resented the best characteristics of VSWR in the frequency range 3 GHz to 5 GHz. It comlies with the VSWR equal to1.8. A. Simulation Results In this section, the roosed Ultra Wide Band microstri antenna was designed using ADS momentum based on rectangular atch with dimensions of width and length.6 mm and 16.95 mm resectively. he width and length of the feeding line is 3.1 mm and 1.4 mm. he roosed geometry design of rectangular atch antenna using ADS Layout is illustrated in Fig.8. VSWR1 5 4 3 1.5 3.5 4.5 5.5 6. freq, GHz Fig.1. VSWR simulation result he radiation attern of UWB antenna is deicted below (Fig.11). We are getting one lobe (main lobe) which corresonds to the theoretical radiation attern of atch antenna radiant. Fig.8. Basic geometry of the rectangular atch antenna Figure 9 shows the return loss amlitude as a function of the frequency (S11) of the designed UWB antenna. he obtained result indicate that the antenna has UWB characteristics with a return loss below -1 db in the frequency band from 3 GHz to 5 GHz and the resonance frequency is centered at 4.3 GHz. (a) (b) Fig.11. 3D radiation attern: (a) Front view, (b) Oosite view able 1 shows the simulation of directivity and gain of microstri antenna of the rectangular atch. Directivity, Gain and ower radiated are imortant arameters to determine the iciently of antenna. Gain of 3.48 is achieved.

17 IJ-SA, Volume 1, N, Secial Issue ESA, July 16. able 1. Antenna Parameters Power radiated (Watts).4949 Effective angle ( degrees) 159.6 Directivity (db) 6.543 Gain (db) 3.488 Maximum intensity (Watts/ Steradian).1776 /MHz that comlies with the FCC mask and the band width is GHz at -1 db. 4, mv 6 4 - B. ime - Frequency Domain Characteristics of Microstri Antenna UWB Radar system is used to determine the velocity, range or detection of any target. UWB radar transmits a short ulse that reflects from range any target in the channel and detected by UWB receiver to find the roerties of target. he UWB ulse generator is connected to the microstri antenna (Fig.1). he radiated ulse is reflected by the object and detected with the receiver antenna. dbm(s) -4-6 8 9 1 11 1 13 14 15-4 -6-8 -1 time, nsec (a) -1-14 1 3 4 5 6 7 8 9 1 freq, GHz (b) Fig.14. Radiation ulse : (a) time domain, (b) frequency domain Fig.1. Microstri antenna connected to UWB ulse generator In this simulation (Fig.13), the excitation ulse is characterized by amlitude about 7 mv, duration of the ulse is aroximately 1 ns and the frequency range [3-5] GHz. 1 5-5 -1 9. 9.5 1. 1.5 11. 11.5 1. time, nsec Fig.13. Excitation signal Figure 14 (a) shows, in time domain, the radiated UWB ulse for rectangular atch antenna which is characterized by maximum amlitude of 53 mv. Figure 13(b) resented, in frequency domain, the PSD of the ulse radiated by the atch antenna.we note the maximum PSD is less to -41.3 dbm V. CONCLUSION Ultra Wide Band radar is a detection system which used a short ulse in order to detect or identify a moving target. he roosed UWB ulse generator has been studied at the frequency of 4.1 GHz and frequency range from 3.1 to 5.1 GHz. his new shae of UWB generator contains a triangular ulse, sine wave oscillator and multilier. Firstly, we have designed a ulses generator circuit using the tool Advanced Design system. Secondly, the design and simulation of rectangular microstri atch antenna that oerates in UWB frequency range 3.1 5.1 GHz] was successfully designed using advanced design system Momentum. When this antenna is imlemented it could be used to transmit or receive signals in the frequency range of the UWB system. hus, we have simulated the global architecture of UWB transmitter containing the designed generator circuit and UWB microstri antenna. he results shows the erformance of this circuit which is generated and radiated a UWB signal centered at frequencies of 4.1 GHz, the bandwidth of GHz and the PSD of -41.3 dbm/mhz. he biomedical alications of Ultra Wide Band radar system romise a very imortant means to remotely monitor hysiological signal. As future research work, we interested on the design of UWB ulse roagation into a layered model

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