Bruno Piovano

CAD and optimization of compact ortho-mode transducers

We describe a new, efficient, computer-aided optimization technique for compact ortho-mode transducers (OMT). As an example, we refer to the full-wave design of an OMT operating in the 17-18.5 GHz frequency band; this design has been entirely carried out at computer level and demonstrates a significant advantage in terms of development times and no need of post manufacturing adjustments. The very satisfactory agreement between experimental and theoretical results further confirms the validity of the proposed technique.

Full-wave design and optimization of circular waveguide polarizers with elliptical irises

We describe the design and optimization of a new polarizer structure realized in circular waveguide with insertion of elliptical irises. The device is compact, showing a considerable reduction in size and weight when compared to previously known realizations. It requires manufacturing by milling techniques only and, since it is composed entirely by waveguides with separable cross sections, it is also well suited for electromagnetic modeling. Measured and theoretical results for a polarizer with a 90/spl deg//spl plusmn/1/spl deg/ differential phase shift and a return loss better than 35 dB for both polarizations over the operating frequency band confirm the validity of the proposed design.

Switched Beam Antenna Employing Metamaterial-Inspired Radiators

We present a novel switched beam antenna (SBA) consisting of four identical metamaterial-inspired electrically short printed monopoles, vertically placed at the corners of a grounded square board. The antenna is designed to operate in the frequency range 1600-2700 MHz, with global dimensions 120 mm × 120 mm × 30 mm. The SBA has been first numerically simulated and optimized and, then, fabricated and tested. Numerical and experimental results show a good agreement. The obtained switched beam capabilities, the achieved realized gain levels, and the synthesized radiation pattern shapes on the horizontal plane, make the proposed SBA a good candidate as a radiating element of a receiving module for wireless telecommunication systems (DCS, UMTS, Wi-Fi, LTE) in areas with reduced signal coverage and/or high interference levels.

Electromagnetic Field Zones Around an Antenna for Human Exposure Assessment: Evaluation of the human exposure to EMFs.

The regulatory framework on human exposure to electromagnetic fields (EMFs) is a crucial task that the telecommunication operators and the authorities have to face. Some procedures have been introduced in standards, based on both computations and measurements, for the assessment of the compliance of the radio transmitters to the given EMF limits. The procedures could vary depending on the position of the observation point around the transmitting antennas. In this article, the definitions of EMF zones and the zones boundaries around an antenna are revised and tailored for the evaluation of human exposure to the EMFs. The space around the antenna is sectioned into three regions: reactive, radiating near field, and far field. The analytical and numerical results are used to support the proposed regions boundaries. Some examples of region boundaries are given for a few antenna types.

CAD of Waveguide Butler Matrices Including Mechanical and Thermal Constraints

Modern CAD tools make feasible to perform an integrated design of microwave networks that accounts also for mechanical and thermal constraints. In this contribution we examine the application of such design approach to Butler matrices, frequently employed in advanced satellite antennas. By using the proposed technique it is shown that Butler matrices implemented in nonstandard waveguide and with compensated bends in order to reduce size and weight can successfully rival microstrip implementations at X-band and pave the way to sophisticated antenna designs at Ka-band.