Luca Marcaccioli

Design of large mm-wave beam-scanning reflectarrays

Beam scanning reflectarrays represent an attractive alternative to MMIC-based phased array antennas, particularly at mm-wave frequencies, thanks to their potential low costs and high performance. In this paper a simple but effective reconfigurable reflecting element is presented and the design procedure is described. An architecture for 2-D electronic beam steering with reduced number of control signals, suitable for large reflectarray antennas, is presented. To demonstrate the feasibility of the proposed solution a prototypal reflectarray antenna operating at 25 GHz has been designed and fabricated. Comparison with measured results shows very good agreement and confirms the capability to electronically steer the antenna beam

A novel rotman lens in SIW technology

This paper presents a novel Rotman lens in low-cost substrate integrated waveguide (SIW) technology. An original solution is proposed for the design of the adsorbing load at the sidewalls of the lens and for the phase-shifters at the output ports. A three beam prototype feeding an 8-element array working at Ku band has been fabricated and tested.

Waveguide Pseudoelliptic Filters Using Slant and Transverse Rectangular Ridge Resonators

This paper presents a novel class of resonators suitable for the design of waveguide pseudoelliptic filters. The basic structure is a rectangular ridge arbitrarily located and oriented within a rectangular waveguide sized to allow the propagation of the fundamental TE10 mode. The ridge has the capability to provide both a reflection and a transmission zero, thus behaving as a singlet. The coupling coefficients of the resonator can be controlled by varying the position and orientation of the ridge, or by additional elements such as irises or ridge taps. Compact pseudoelliptic filters can be designed by cascading multiple ridges and half a wavelength waveguide sections. A practical design procedure is presented. The experimental results of a fifth-order filter with three resonant ridges validate the proposed approach.

A Novel Class of Compact Dual-Mode Rectangular Waveguide Filters Using Square Ridge Resonators

A novel dual-mode resonator for the design of compact waveguide filters is proposed in this paper. The resonator consists of a nearly-square ridge realized into a rectangular waveguide that supports the fundamental TE10 mode. With this configuration two degenerate modes can resonate along orthogonal directions within the gap between the ridge and the opposite waveguide wall. By combining multiple ridges, higher order filters with pseudo-elliptic response can be realized within compact waveguide sections. A 4th order filter with two transmission zeros has been designed, manufactured and tested proving the feasibility of the proposed class of filters.

Electronic steerable MEMS antennas

Recent advances in the technology of radiofrequency (RF) circuits, such as RF-microelectromechanical systems (MEMS) make it possible to practically implement electronically reconfigurable antenna arrays paving the way to innovative communication systems including applications such as next generation mobile communications, radar applications, remote sensing and imaging. This paper reviews the basic implementations of such antenna systems, namely phased arrays and reflectarrays, as well as the algorithms allowing for beam shaping, beam steering, null placing etc., as well as the typical RF-MEMS circuitry for both amplitude and phase control.

A Novel Compact Dual Band Reconfigurable Power Divider for Smart Antenna Systems

This paper presents a novel compact dual band reconfigurable power divider for smart antenna systems. The circuit employs two cascaded dual band hybrid couplers connected through two dual band discontinuities. The dual band discontinuities, consisting of a diplexer and two varactor diodes, can be tuned through two different biasing voltages thus allowing an independent and arbitrary choice of the power ratio in the two frequency bands. A prototype has been designed to operate in the dual band WLAN frequency range, and fabricated in microstrip technology on a 25 mils CER10 substrate. Measured scattering parameters exhibit good performance in terms of return loss, insertion loss and isolation in both WLAN bands, confirming the feasibility of the proposed architecture. The compactness of the circuit makes it suitable for employment in array configurations.

A novel phase-only method for shaped beam synthesis and adaptive nulling

A new method for phase-only synthesis of linear array antennas is proposed. The phase distribution of the array excitation can be described by a weighted sum of proper basis functions. By optimizing the weights of this sum, rather than the phase of each element, the problem becomes almost independent of the size of the array. The present work shows that with this method both beam shaping and interference nulling can be achieved. The very fast convergence of the optimization makes it suitable even for real-time applications.

An original resonant Y-junction for compact waveguide diplexers

This paper presents an innovative resonant Y-junction for the design of compact rectangular waveguide diplexers. The junction contains an elliptic ridge which serves as common dual-mode resonator for both channel filters. The junction itself constitutes therefore the first resonators of the filters, thus allowing for considerable size reduction with respect to the conventional diplexer implementation. The orientation of the input branch and the insertion of irises and ridge taps are used to control the coupling coefficients within the junction. An X-band diplexer employing the proposed junction in combination with H-plane cavity filters has been designed, manufactured, and successfully tested.

Flat Array Antennas for Ku-Band Mobile Satellite Terminals

This work presents the advances in the development of an innovative flat array antenna for Ku-band mobile satellite terminals. The antenna is conceived to allow a bi-directional high data rate satellite link. The available circular surface (diameter 110 cm) integrates both a transmitting and a receiving section, operating in orthogonal linear polarizations. The TX frequency range is fully covered while the RX bandwidth is around 300 MHz arbitrarily allocated on the DVB range depending on requirements. The beam is steered in elevation through a phased array architecture not employing costly phase shifters, while the steering in azimuth is mechanical. Active BFNs in printed circuit technology allow excellent performance in terms of EIRP (42 dBW/1MHz, ITU-R S.728.1) and G/T (13 dB/°K at 40° in elevation), maintaining extremely low profile (< 5 cm, radome included). Gain as high as 32 dBi is achieved thanks to the use of slotted waveguide technology, while low fabrication costs are ensured by the employment of innovative SIW (substrate integrated waveguide) structures. In the design fabrication cost is considered as a driving factor, yet providing high performance with a flat profile and thus resulting in a great commercial potentiality.

Design of a Broadband MEMS-based reconfigurable coupler in Ku-band

A broadband reconfigurable coupler has been realized at Ku band making use of RF-MEMS switches. The coupler is directly printed on the same Silicon substrate on which the MEMS are built. The device works at 16-20 GHz, and it is designed to provide two different coupling levels of -10 dB and -17 dB, maintaining good matching and isolation in both states. Performance significantly matches the simulations, verifying how close the MEMS switches perform to the predicted behavior. This also demonstrates that the MEMS fabrication process is repeatable and predictable.