Introduction Antenna Design Optimization of the Acid Catalyst Concentration for Synthesis of Anti‐Cancer Agent Gamavuton‐0 by Using Mathematical and Statistical Software

330 Fig. . Reflection phase has been simulated and investigated. At . Gz, the reflection phase as shown in Fig. . is degree. t means at . Gz, the unit cell has high impedance characteristic because this is in the ±π band which is high impedance surface bandwidth and also works as forbidden band gap for surface waves propagation. Figure 2. Unit cell structure dimension. Figure 3. Reflection phase simulation result of the unit cell. This unit cell is implemented on the bottom substrate layer subtract of the conventional antenna which is designed with two unit cells as shown in Fig. . The second substrate layer remains the same with radius of circular patch is . mm. 331 F igure 4. Bottom layer substrate configuration with 2 unit cell.

3. Result and Discussion

The antenna with S was fabricated and measured and shown in Fig. . The comparison between simulation and measurement results are presented in Table . a b Figure 5. Fabricated antenna top view of a first layer b second layer. Table 1. Result comparison Parameter Simulation Antenna without HIS Simulation Antenna with HIS Measurement Antenna with HIS S dB ‐ . ‐ . ‐ . S dB ‐ . ‐ . ‐ 8. S BW Gz . – . . 8 – . . – . S BW Gz . – . . 8 – . . ‐ . Gain port . dB .8 dB , dB Gain port . dB , 8 dB , dB nput mp. Ω . 8 – . i .8 – . i ,8 ‐ , i Rad. Eff port 8 . . na Rad.Eff port 8 . . na From Table , simulation result of antenna with S can be compared to simulation result conventional antenna. Simulation result of antenna with S obtained at port shows the impedance bandwidth S BW is increased to Mz and gain increases .8 dB compared to conventional antenna. Meanwhile at port the S BW increased Mz with gain of . dB higher than conventional antenna result. Therefore, from the simulation result, the antenna with S substrate has larger 1 2 332 bandwidth, improved gain, and also increased radiation efficiency . for port and ,88 for port . The S antenna also improves the input impedance to its reference impedance. The reference impedance for differential‐fed antenna is twice of the single ended antenna impedance which is Ω. a b c d Fig. 6. Radiation Pattern for a port 1 phi=0, b port 1 phi=90, c port 2 phi =0, d port 2 phi=90 Antenna with S substrate has been fabricated and measured to validate the simulation result of the antenna with S substrate. Antenna measurement has been conducted in anechoic chamber, Telecommunication Laboratory, Department of Electrical Engineering, Universitas ndonesia. Table shows similarity between measurement result and simulation result. Another result showed in Fig which shows radiation pattern comparison between measurement and simulation result. Both result and ports show directional radiation pattern. The slight differences between measurement and simulation result is due to imperfect fabrication process which affects the input impedance. 333

4. Conclusion

This paper presents a high impedance surface substrate implemented on a differential‐fed circular patch microstrip antenna. Antenna with S substrate has been fabricated and measured to validate the simulation result. Measurement result shows larger bandwidth and increased gain compared to simulation result of conventional antenna. Gain antenna shows . dB enhancements for port and . dB for port . Directional radiation pattern has been proved by measurement result. S also increases the radiation efficiency of . for port and .88 for port . Acknowledgements This work was partly supported by Penelitian Unggulan Perguruan Tinggi” from the Ministry of Research Technology and igher Education Republic of ndonesia. References A. Kumar, J. Mohan, and . Gupta, Surface wave suppression of micrpstrip antenna using different EBG designs,” nternational Conference Signal Processing and Communication, , Noida, pp. ‐ . D. Sievenpiper, Z. Lijun, R.F.J. Broas, N. G. Alexapoulus, and E. Yablonovitch, igh‐impedance electromagnetic surfaces with a forbidden frequency band”, EEE Transactions on Microwave Theory and Techniques, vol. , pp. ‐ , . F. Faishal, A. Ahmad, U. Ali, S. Ullah,”Performance Analysis of a , Gz Plannar Antenna using Different Type of Wearable Artificial Ground Planes”, th nt. Conf. on igh‐Capacity Optical Networks and EnablingEmerging Technologies, slamabad, Dec ‐ , pp. ‐ G Z. Tong, A. Stelzer, and W. Menzel, mproved Expressions for Calculating the mpedance of Differential Feed Rectangular Microstrip Patch Antennas,” EEE Microwave and Wireless Componets Letters, , pp. ‐ . Sun, An Enhanced Rectenna Using Differentially‐Fed Rectifier for Wireless Power Transmission”, EEE Antennas and Wireless Propagation Letters, , Vol. , pp. ‐ .A P. Kovacs, T. Urbanec,”EBG Structures: Practical Tips and Advice for Antenna Engineers” Z. Tong, A. Stelzer, C. Wagner, R. Feger, and E. Kolmhofer,”A novel differential microstrip patch antenna and array at Gz,” Available on: ap‐s.ei.tuat.ac.jpisapx 8pdf .pdf