DESIGN, DEVELOPMENT AND PERFORMANCE ANALYSIS OF RECONFIGURABLE LOG PERIODIC ANTENNA FOR RF FRONT-END MULTI STANDARD TRANSCEIVER

Transcription

1 International Journal of Electronics and Communication Engineering and Technology (IJECET) Volume 9, Issue 6, November-December2018, pp , Article ID: IJECET_09_06_004 Available online at ISSN Print: and ISSN Online: IAEME Publication DESIGN, DEVELOPMENT AND PERFORMANCE ANALYSIS OF RECONFIGURABLE LOG PERIODIC ANTENNA FOR RF FRONT-END MULTI STANDARD TRANSCEIVER Dhiraj Tulaska Research Scholar, Dept. of E and TC Shri Sant Gajanan Maharaj COE Shegaon , India (MS) Dr..K.B.Khanchandani Professor, Dept. of E and TC Shri Sant Gajanan Maharaj COE, Shegaon , India (MS) ABSTRACT In this paper a novel design of Reconfigurable Log-Peiodic Antenna presented. It is designed on FR4 substrate (ϵ r =4.4) and simulated in Keysight s Advance Design System Momentum Microwave Software. The resonant frequency band of the designed antenna is 1.0 to 4.0 GHz. It covers the all the available multi standards. The return loss for designed antenna over the given band is less than -10 db, with gain from 4 to 6dB.This antenna can give the best performance for recent RF Front-end multistandard transceivers. Keywords: Planer Reconfigurable Antenna, FR4, Multistandard, Front-End, Transceivers Etc. Cite this Article: Dhiraj Tulaska and Dr. K.B.Khanchandani, Design, Development and Performance Analysis of Reconfigurable Log Periodic Antenna For RF Front-End Multi Standard Transceiver. International Journal of Electronics and Communication Engineering and Technology, 9(6), 2018, pp INTRODUCTION In 1957, R.H. Du Hamel and D.E. Isbell [12] available the first work on what was to become known as the log periodic array. A Planar Reconfigurable Log Periodic Antenna structure is shown in figure 1.1.These antennas are also called as V-antennas. They are also known as frequency independent antennas. Log periodic antennas are uneven, simple and versatile. It consists of metal strip whose edges are specified by the angle α/2.these are remarkable 30 editor@iaeme.com

2 Dhiraj Tulaskar and Dr. K.B.Khanchandani antennas which exhibit relatively uniform input impedances, VSWR, and radiation characteristics over a wide range of frequencies. [13]The design is so simple that in retrospect it is remarkable that it was not made-up earlier. In essence, log periodic arrays are a group of dipole antennas of varying sizes strung together and fed alternately through a common transmission line. Still, despite its simplicity, the log periodic antenna remains a subject of considerable study even today. The log periodic antenna works the way one intuitively would expect. Its active region, is that portion of the antenna which is actually radiating or receiving radiation efficiently. It shifts with frequency.[14] The longest element is active at the antenna s lowest usable frequency where it acts as a half wave dipole. As the frequency shifts upward, the active region shifts forward. The upper frequency limit of the antenna is a function of the shortest elements.[1-2] Figure 1.1 Designed Prototype 2. DESIGN & ANALYSIS The main design parameters of Log Periodic Dipole Array are τ, α, and σ.these parameters should be accurately calculated in order to tune to the desired band of frequency. Two factors, tau (τ) and sigma (σ), are for the most part the only factors we need to consider. Tau, as mentioned, is the ratio of the length of one element to its next longest neighbor. Sigma is known as the relative spacing constant and along with τ determines the angle of the antenna s apex, α. The designed angle α is calculated by 1 4σ α cot (2.1) = 1 τ =22.61 For EMC work, we would like to keep the antenna as compact as possible, and we can do so by selecting a low tau. We also would like to keep the gain fairly low so as to avoid too narrower beam width. We will choose a sigma of 0.12 and a tau of 0.8, which should produce an antenna with a gain of approximately 6.5 db over isotropic [3-4]. Fig 2.1- The parameters tau and sigma can be chosen from this graph. We chose a tau of 0.8 and a sigma of 0.12 for a predicted gain of 6.5 dbi. The line for optimum sigma is for those designers to have maximum gain.[12, 14] editor@iaeme.com

3 Design, Development and Performance Analysis of Reconfigurable Log Periodic Antenna For RF Front-End Multi Standard Transceiver Here, Geometric ratio or scale factor is given by f1 Rn τ = = (2.2) f2 Rn+ 1 = 0.8 Spacing factor is given by σ = Rn + 1 Rn 2ln+ 1 (2.3) d σ = 2l n n σ = [ ] ( ) Active Re gion Bandwidth Bar = τ cot α 2 [ ] ( ) Bar = τ cot α =1.839 F F max Designed Bandwidth = Bs = Bar = Fmax Bs = Bar F min min (2.4) (2.5)..(2.6) λ = max µ f min Where µ is light velocity = 3x10 8 m/s (in vacuum) = feet Total length is calculated by (2.7) λmax 1 L = 1 cot ( α ) 4 Bs (2.8) = 0.802m=2.631 feet /6 inch = 5.253inch l = l τ 2 1. = 29.52x0.8=23.64 Center to center spacing between dipole is Z0 s = d cosh 120 (2.9) = 2.5 inch Z 0 - Characteristic impedance D - Width of dipole elements Number of dipole elements is calculated by 32 editor@iaeme.com

4 Dhiraj Tulaskar and Dr. K.B.Khanchandani ln N = 1+ ln ( Bs) ( 1 ) τ = 9 New spacing factor or relative mean spacing is given by (2.10) ' σ σ = τ (2.11) Log periodic dipole array has the parameters which are related as 1 l2 ln+ 1 R2 Rn+ 1 d2 dn+ 1 s2 sn+ 1 = = = = = = = = (2.12) τ l l R R d d s s 1 n 1 n 1 n 1 n Average characteristic impedance is calculated by ln Z a = 120 ln 2.25 dn (2.13) Log periodic designs vary, but the one most commonly used for EMC work is the Reconfigurable Log Periodic Dipole Array (RLPDA).This antenna covers the frequency bands from 1.0 to 4.0 GHz. The simplified view is shown in fig 2.2[5-6] Figure 2.2 Simplified view of general LPDA Here, each element is shorter than the element to its left.[8] Ratio of each element to each adjacent element is constant, and is referred to as tau (τ). The other critical dimension is the spacing between elements. Distance d 1,2 for example, is the distance between the left most element and its nearest neighbor.[7-8] The distance between two adjacent elements is equal to: 1 d1,2 = ( l1 l2 ) cotα (2.14) editor@iaeme.com

5 Design, Development and Performance Analysis of Reconfigurable Log Periodic Antenna For RF Front-End Multi Standard Transceiver Table 2.1 (a) Designed parameters of LPDA for 1.0 to 4 GHz Element Formula Length (inches) Final design values (inches) l 1 (492/200) ft. (29.52/6) inch 4.92 l 2 l 1 τ l 3 l 2 τ l 4 l 3 τ l 5 l 4 τ l 6 l 5 τ l 7 l 6 τ l 8 l 7 τ l 9 l 8 τ Table 2.1 (b) Designed parameters of LPDA for 1.0 to 4.0 GHz Spacing Between Elements Formula Distance (inches) Final design values (inches) d 1,2 0.5(l 1 - l 2 ) cot α (7.08/6) inch 1.18 d 2,3 d 1,2 τ d 3,4 d 2,3 τ d 4,5 d 3,4 τ d 5,6 d 4,5 τ d 6,7 d 5,6 τ d 7,8 d 6,7 τ d 8,9 d 7,8 τ Table 2.2-Width of dipole elements (1/τ=dn+1/dn) Width of dipole element In inches W W W W W W W W W PRACTICAL & SIMULATION RESULT In operation, the LPDA works as follows. Assume that in the designed prototype, we are operating at a frequency range in which the third (middle) element is resonant. Elements 2 and 4 are slightly longer and shorter, respectively, than element 3.[9] Their spacing, combined with the fact that the transmission line flips 180 degrees in phase between elements allows these two elements to be in phase and nearly (but not quite) resonant with element 3. Element 4, being slightly shorter that element 3 acts as a director shifting the radiation pattern slightly forward. Element 2, being slightly longer, acts as a reflector further shift the pattern forward. The net result is an antenna with gain over a simple dipole. As the frequency shifts, the active region (those elements that are receiving or transmitting most of the power) shifts along the array. Having select tau and sigma, we simply plug in the numbers [9-10] editor@iaeme.com

6 Dhiraj Tulaskar and Dr. K.B.Khanchandani Now comes the tricky part. We have to select the characteristic impedance of the transmission line that feeds the elements, a transmission line that also acts as the boom of the antenna. We will call this transmission line impedance Z b [13] Where, Z d is the average characteristic impedance of a simple dipole antenna. As stated previously, Z b is the characteristic impedance of the boom, itself a transmission line (referred to as the antenna feeder line).[10] Z i is the impedance of the antenna as seen from its input terminals. Those terminals are usually connected to some kind of balun which performs the balanced to unbalanced conversion and steps down the impedance Z i to match the impedance of the signal source (when transmitting) or receiver input (when receiving) ). The impedance is of this line; referred to as the coax feed line is usually 50 ohms and we will refer to it as Z 0.[11] We have chosen to make the antenna elements from 1/4 inch width. That makes the impedance Z d of the longest element: Next we choose the spacing between the two booms. The booms will consist of one- Note that each quarter inch rods to which the left and right elements are alternately attach. element is fed 180 degrees out of phase with the elements adjacent to it. For reasons that will become apparent shortly, we will need to choose a relatively high impedance to feed the booms (Z i ). We will choose 200 ohms. This impedance is four times the characteristic impedance of our coaxial line (Z 0 = 50 ohms) and is readily produced through the use of a balun with a 2:1 ratio of windings. The spacing between the two booms needs to be [13] Where, diam = diameter of each boom in inches. S = center-to-center spacing between the booms in inches editor@iaeme.com

7 Design, Development and Performance Analysis of Reconfigurable Log Periodic Antenna For RF Front-End Multi Standard Transceiver Fig7.3 (a) Measured S11 for 1.0 to 4.0GHz band (b) Measured VSWR for 1.0 to 4.0 GHz band 4. CONCLUSION A Reconfigurable Log Periodic antenna is designed on FR4 substrate using ADS momentum. The layout is simulated in momentum microwave simulator. The designed antenna gives a resonant frequency over the band from 1.0 to 4.0 GHz with good return loss. The simulated results match with the measured results. REFERENCES [1] Hailin Design and simulation of pattern reconfigurable antenna based on RF-MEMS by the American Institute of Aeronautics and Astronautics pp1-9 by 2012 [2] Kalyani P. Dakhale, And M.S. Narlawar Design Of Novel Vivaldi Antenna For Cognitive Radio Application In Ultra WideBand International Journal of Industrial Electronics and Electrical EngineeringVolume-3, Issue-3, March-2015 [3] InsuYeomet.al. Analysis of RF Front-End Performance of Reconfigurable Antennas with RF Switches in the Far Field Hindawi Publishing Corporation International Journal of Antennas and Propagation Volume editor@iaeme.com

8 Dhiraj Tulaskar and Dr. K.B.Khanchandani [4] MunyongChoiet.al. A Compact Frequency Reconfigurable Antenna for LTE Mobile Handset Applications Hindawi Publishing Corporation International Journal of Antennas and Propagation Volume 2015 [5] MunyongChoiet.al. A Compact Frequency Reconfigurable Antenna for LTE Mobile Handset Applications Hindawi Publishing Corporation International Journal of Antennas and Propagation Volume 2015 [6] Harish Rajagopalan et.al. MEMS Reconfigurable Optimized E-Shaped Patch Antenna Design for Cognitive Radio Ieee Transactionson Antennas And Propagation, Vol.62, No.3,March2014 [7] Joseph Costantine et.al. Reconfigurable Antennas: Design and Applications Proceedings of the IEEE Vol. 103, No. 3,pp-424 to 437 March 2015 [8] Walizade et.al. Design Of Reconfigurable active Integrated Antenna by IET Microw. Antennas Propag., 2015, Vol. 9, Iss. 9, pp & The Institution of Engineering and Technology 2015 [9] Miroslav Joler and JoskoKucan Impact of Slot Parameters on the Three Resonant Frequencies of a Rectangular Microstrip Antenna IEEE Antennas & Propagation Magazine August 2015 [10] M. Borhani, P. Rezaei, and A. Valizade Design of are configurable miniaturized microstrip Antenna for switch able multi band systems Ieee antennas and wireless propagation letters,vol.15,2016 [11] Le Huy Trinh et.al. Influence of component ESR on a 4G frequency reconfigurable antenna Proceedings of the IEEE pp [12] The ARRL Antenna Book, The American Radio Relay League, Newington, CT, [13] R. H. DuHamel and D. E. Isbell, Broadband Logarithmically Periodic Antenna Structures, 1957 IRE National Convention Record, Part 1. [14] R. L. Carrell, The Design of Log-Periodic Dipole Antennas, 1961 IRE International Convention Record, Part editor@iaeme.com