Nicolas Fortino

Design Optimization of UWB Printed Antenna for Omnidirectional Pulse Radiation

The use of ultrawideband technology in many applications implies the use of a suitable radiating structure, especially for pulsed systems. The development of a triangular CPW-fed printed antenna with specific ground plane shape is presented. First the triangular element was optimized to minimize return losses and size of the antenna in the [3.1-10.6] frequency band. The evolution of radiation patterns with frequency was also studied, as changes in phase center position and radiation characteristics alter the integrity of transmitted pulses. Thus the antenna ground plane shape was modified in order to maintain almost constant radiation patterns over the entire bandwidth. Time domain measurement methods were used to characterize the antennas and validate these improvements. The procedure is presented and results are plotted in a 3D format and discussed.

Frequency and Time Domain Analysis of Different Approaches to the Backing of an UWB Slot Antenna

The presence nearby of a parallel metallic plane usually impairs the radio-electric performance of planar ultrawideband (UWB) elements such as monopole and slot antennas. Two comparative approaches to this problem are studied, in the frequency and time domains. Conservation of the UWB performance of a slot antenna is investigated in order to obtain a mono-directional quasi-planar element suitable for an UWB array. First, the addition of a planar reflector is studied: up to a certain distance, wide impedance bandwidth is maintained, but the antenna offers a non-uniform gain. Secondly, the addition of a cavity overcomes this disadvantage and makes the cavity-backed slot antenna one of the best candidates for an UWB quasi-planar array.

Comparative study using an UWB measurement system and a RAMAC GPR system for subsurface imaging of the vaucluse karst aquifer

We have presented comparative study with a realistic field-test in the tunnel of the Vaucluse aquifer, of two different microwave imaging systems - the 250 MHz RAMAC pulsed system and the ultra-wideband ETSA system. These initial results are very promising especially regarding the improved resolution of the ETSA image and the concomitant greater depth of penetration. Future work will focus on establishing a quantitative norm for comparing image quality, both in amplitude and frequency.

Dual complementary planar antennas for highly isolated Tx/Rx UWB systems

Recent advances in wideband impulse technology, low power communication along with unlicensed band have enabled ultra-wide band (UWB) as a leading technology for future applications. This paper outlines an Impulse Radio Ultra Wideband (IR-UWB) application focusing on the design of the antennas and especially on the excellent isolation between Tx and Rx antennas operating on a same PCB board. The decoupling is obtained thanks to Babine ts principle. All these studies were performed for the low band FCC, from 3 to 5 GHz (specifications: Spp<;-6dB and Spq<;-30dB with p= 1; 2 and q= 1; 2).