Design and Analyis of Compact Ultra-wideband Inverted F-L Microstrip Patch Antenna For Intelligent Transportation Communication Systems Yasser M. Madany Darwish A. Elaziz Wael A. Elkrim Communications and Electronics Depart., Arab Academy for Science &Technology, Alexandria, Egypt waelaboomar@yahoo.com Member IEEE, Communications and Electronics Depart., Alexandria University Alexandria, Egypt ymadany@ieee.org Member IEEE, Communications and Electronics Depart., Arab Academy for Science &Technology, Alexandria, Egypt darwish4650@yahoo.com Abstract-UItra-wideband (UWB) radio is a technology that has a wide range of applications including range measurement, materials penetration, and low probability of interception and interference communication systems. UWB signals are unusual, because they have a bandwidth greater than 25 percent of center frequency compared to less than unity percent for conventional radio signals. Recent developments make it possible to build a transmitter and receiver on a single chip at low cost. The intelligent transportation system (ITS) applications will use very low radiated power levels, usually less than a milli-watt. These capabilities are possible with current solid state electronics and low-cost chips can be made to perform a wide range of applicat- ions. The proposed compact ultra-wideband antenna structure has been analyzed using a commercial software and the radiation characteristics, such as, return loss, VSWR, input impedance, radiation patterns and the surface current densities have been introduced and fabricated, which offered excellent performance and have measured lower return loss up to -31.4 dB with percentage bandwidth 22.34 %. Keywords-Ultra-wideband communications; inverted F-L patch antenna; ITS appcations; finite element method I. INTRODUCTION Ultra-wideband technology is a field of communications and radar that uses ultra-short pulses of energy and complex pulse trains for sensing and communication. The distinguishing characteristic of uItra-wideband signals is their large ratio of instantaneous bandwidth to center equency [1]. For comparison, normal narrowband signals have bandwidth-to- center equency ratios that are around 0.0 I or less, and wideband signals (e.g., spread spectrum signals) have bandwidth-to-center equency ratios that are about 0.01-0.25. However, UWB signals have bandwidth-to-center equency ratios that are 0.25 or larger by the American definition. Russian texts classi UWB as having a bandwidth 100 percent of center equency [2]. The large bandwidth means that UWB signals can carry more information, such as, range resolution, target interaction, and data, than can narrowband signals. UItra- wideband impulse signals can be produced by generating an electromagnetic energy pulse that may be about a nanosecond in duration. This makes the pulse duration on the same order as one  cycle at one GHz. There are many references described the applications that assumed ultra-wideband impulses signals, sometimes called non-sinusoidal signals. There are other UWB waveforms that may have ITS applications in the far ture. In addition to the short duration pulses, these devices can be made 978-1-4673-0292-0112/$31.00 ©l012 IEEE with very high pulse repetition equencies on the order of one MHz (one S pulse repetition interval). Varying the interval between impulses can modulate the signal to carry information [3]-[5]. By using correlation of pulse interval coded signals, these devices can both communicate and measure distances very exactly. The phrase intelligent transportation system (ITS) describes a number of different concepts that will apply advanced technology such as remote sensors, computers, communication, and automatic control to highway transport- ation problems. Some nctions of an ITS include the collection, distribution, and use of various information technologies to improve the transportation system's safety, efficiency, and mobili. Most ITSs will have the same basic components. All ITSs will need sensors and communication transceivers to collect and distribute information. As currently foreseen, the UWB devices for an ITS will be relatively simple and use off-the-shelf technology. Therefore, UWB devices can offer accurate location and sophisticated communication at an affordable price. In this paper, compact ultra-wideband inverted F-L (IFL) microstrip antenna with slotted structures arrangement and tuning stub has been introduced, which has been designed to meet the requirements for UWB comm- unications ITS applications. The proposed antenna design has been fabricated and the radiation characteristics measured using network analyzer HP8719ES whose equency range om 0.05 to 13 GHz. The enhancement design and its varieties have been analyzed using SS simulator [6] and the radiation characteristics, such as, return loss, VSWR, input impedance, radiation pattes and the surface current densities for some equencies have been introduced to illustrate the performance compared with different conventional IFL antenna [7]-[12]. II. ANTENNADESIGNSTRUCTURE The compact ultra-wideband inverted F-L microstrip patch antenna with slotted structures arrangement on the ground plane side and tuning stub on the inverted L-patch has been introduced and analyzed. The proposed antenna is designed and fabricated on Rogers R03010 substrate with a dielectric constant of 10.2, a thickness of 0.635 mm and a loss tangent of 0.0035. The 3D, bottom and top sides view without dielectric substrate of the proposed compact antenna and its mechanical parameters in millimeter are shown in Fig.l. For the best performance of the proposed antenna to operate at the desired ultra wide resonant equency band, the effect of the slots on the ground plane must be understood, as shown in Fig.2. Thus,