Investigations of Heat Sink Property of a Novel Dual Linear Polarized Low Cross-Polarization X-Band Phased Array Antenna Employing Silicon RFICs-Based Beamforming Network

In this paper, investigations on heat sink property of a 4x2 wideband dual linear polarized phased array antenna comprised of 3D metal printed all metallic radiators, serving also as heat sink, is presented for X-band frequency. Two single radiators, each with a height nearly equal to
${\lambda }$
/2 corresponding to center frequency (9.50 GHz), shaped intuitively and placed orthogonal to each other and surrounded by a metal ring of square cross-section with overall dimension of
${\lambda }/2\times {\lambda }$
/2, constitutes the dual linear polarized radiating element. Both radiators are fed by an orthogonal arrangement of stripline feeds through a trapezium shaped metal plate, which in turn helps to integrate the antenna aperture with the beamforming network (BFN). A set of via fences are placed beneath each antenna element, which work as a thermal path between the BFN and antenna aperture. This radiating element resembles heat fins, and designed to cover 8.5-11.5 GHz impedance bandwidth. Good radiation pattern with low cross-polarization is obtained over the entire bandwidth, while the peak broadside gain is varying between 14–11 dBi. Beam scans are viable ±50° in
${\varphi }=0^{0}$
plane and ±30° in
${\varphi }=90^{0}$
plane. The array antenna aperture is built using 3D metal printing technology. The BFN is comprised of commercial silicon Radio Frequency Integrated Circuit (RFIC) chips which have been integrated with the antenna aperture. A beamforming algorithm is applied through serial peripheral interface (SPI) controller to achieve beam steering during the measurement process. The temperature reduction of 60°C is achieved with the heat sink structure when the temperature distribution of BFN with and without heat sink are compared for the 4x2 array. The temperature of the heat sink antenna is only 41°C and the temperature distribution is validated with an infrared (IR) camera.