antenna that obtained from simulation and measurements of fab- ricated purposed antenna are shown. It shows an acceptable and almost flat gain on the frequency bandwidth of antenna. In the frequency about 5.5 GHz, the gain of the antenna drastically drops that causes the antenna do not radiate in this frequency bandwidth. 5. MEASURED RESULTS OF ANTENNA AND COMPARISONS Figure 9 shows VSWR results from measurement and simulation of purposed antenna. With respect to the result, it is obvious there is a good agreement between measurement and simulation values. The negligible mismatches between these values are nor- mal because of human, fabrication, measurement, soldering errors and existence of the noise. The measurements of VSWR curve is done by Agilent 8722EES Analyzer apparatus. The photograph of the fabricated slot antenna is shown in Figure 10. In the Table 1 physical dimensions of purposed antenna with some prototype of PMA with suppressing bandwidth property that discussed in reputable publications recently are compared. As we can see in the table, the smallest antenna is [5] that approximately is 248% larger than our purposed antenna. 4. CONCLUSION In this article, steps of antenna design evolution, analysis and fabrication of a miniaturized planar UWB slot antenna with an interference suppressing capability is shown. This antenna has a microstrip fed line which with printing and fabrication technol- ogy that fabricated and tested on substrate. The results of this miniaturized antenna for IBW 3.05–13.12 GHz and eliminated unwanted bandwidth 4.98-5.96 GHz are measured. Finally, designed antenna with dimensions of 20 3 18 3 1.6 mm 3 in contrast with antennas that have same characteristics is more smaller, efficient and suitable option to wideband systems with- out worn about the interference bandwidth. ACKNOWLEDGMENT The authors thank the Antenna Measurement Laboratory at Iran Telecommunication Research Center (ITRC) for fabricating and testing the antenna presented in this article. REFERENCES 1. Federal Communications Commission: First report and order, Revi- sion of part 15 of the Communication’s rules regarding ultra-wide- band transmission system, Washington, DC, 2002. 2. H. Xie, Y. Jiao, Z. Zhang, and Y. Song, Band-notched ultra- wideband monopole antenna using coupled resonator, Electron Lett 46 (2010), 1099–1100. 3. T. Mandal and S. Das, Ultra wide band printed hexagonal monopole antennas with band rejection, Microwave Opt Technol Lett 54 (2012), 1520–1525. 4. K. Zhang, Y. Li, and Y. Long, Band-notched UWB printed monop- ole antenna with a novel segmented circular patch, IEEE Antennas Wireless Propag Lett 9 (2010), 1209–1212. 5. J.B. Jiang, Y. Song, Z.H. Yan, X. Zhang, and W. 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Azarmanesh, A novel planar UWB monopole antenna with variable frequency band-notch function based on etched slot-type ELC on the patch, Microwave Opt Tech- nol Lett 52 (2010), 229–232. 11. C. Hong, C. Ling, I. Tarn, and S. Chung, Design of a planar ultrawi- deband antenna with a new band-notch structure, IEEE Trans Anten- nas Propag 55 (2007), 3391–3397. V C 2016 Wiley Periodicals, Inc. DESIGN AND INITIAL MEASUREMENTS OF K-BAND FMCW RAIN RADAR WITH HIGH RESOLUTION Ki-Bok Kong, 1 Woo-Ram Jeong, 1 and Seong-Ook Park 2 1 Kukdong Telecom, 78-43 Beagilheon-Ro, Bujeok-Myun, Nonsan- City, Chungnam, Republic of Korea; Corresponding author: kbkong@kdtinc.co.kr 2 Microwave and Antenna Laboratory Department of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-Ro, Yuseong-Gu, Daejeon 305-701, Republic of Korea Received 13 August 2015 ABSTRACT:: This paper presents an FMCW K-band rain radar with the property of high resolution. The radar system was designed for mea- surement of localized torrential rain. Using DDS and FPGA control, heterodyne modulation was used to generate the FMCW down-chirp sig- nal with 50 MHz bandwidth, and emitted a K-band signal with nominal power of 125 mW in the vertical direction. To obtain high resolution for the Doppler spectrum, the radar system used a coherent signal process- ing method. Several experiments were conducted and the results were compared with data from the meteorological administration. V C 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:817–822, 2016; View this article online at wileyonlinelibrary.com. DOI 10.1002/ mop.29677 Key words: rain radar; FMCW; 24 GHz; long range radar; high resolution 1. INTRODUCTION The frequency-modulated continuous wave (FMCW) technique is widely used for weather radar systems [1–4]. Recently, FMCW compact rain radar has designed to measure the local- ized heavy rain [5,6]. It is important to improve the high resolu- tion in order to archive good quality of precipitation measurement [1]. In this paper, we designed a 24 GHz rainfall radar system that radiates electromagnetic waves in the vertical direction, and analyzes the distribution of reflectivity resolved into a 1024 range gate with a vertical rage resolution of 3 m. FMCW radar uses less expensive and lower power RF compo- nents than those of pulse radar. On the other hand, because FMCW radar systems continuously emit electrical signals, leak- age of transmitter signals occurs. Thus high isolation between the transmitter and the receiver is required to improve sensitiv- ity. In order to improve the isolation property, a separation wall with a serration edge structure between the transmitter and the receiver antennas was used [7]. To obtain the Doppler informa- tion with high resolution frequency, coherent operation was used to combine the consecutive range spectra of 1024 numbers. As a result, the frequency resolution is increased and the radar is able to detect relatively slow moving target. The radar system DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 58, No. 4, April 2016 817