Wide-Scan Active Highly Integrated Phased Array Antenna for Tx/Rx Application at K-Band

A new wide-scan active direct-integrated phased array antenna (AIPAA), designed for Tx/Rx mm-Wave applications, is introduced in this paper. This novel AIPAA offers seamless switching performance between transmitting (Tx) and receiving (Rx) modes without the need for lossy intermediate RF components, such as RF switches, circulators, and duplexers. The unitcell of the AIPAA consists of three miniaturized tapered slot elements operating in the K-band frequency range. In the Tx mode, a GaN high electron mobility transistor serves as the power amplifier (PA), while in the Rx mode, a GaAs MMIC low noise amplifier (LNA) is employed. The unticell's center antenna element is reshaped to match closely to the optimal load impedance of the PA (
$\mathrm{Z}_{opt}=6+\mathrm{j} 36 \Omega$
) while the other elements are tuned to maintain a
$50 \Omega$
input impedance suitable for the LNA. This direct integration approach enhances system efficiency and reduces the cost and size by eliminating the need for any intermediate impedance matching networks and RF switching components. The proposed Tx/Rx AIPAA achieves a matching at both the PA (optimum load) and LNA (
$50 \Omega$
) ports with a 6% and 16% fractional bandwidth over ±50° scan coverage, respectively. The switching capability is incorporated by utilizing the ON/OFF modes of the PA and LNA DC-biasing. The proposed AIPAA's cell size is
$9.2 \times 6.5 \times 1.8\ \text{mm}^{3}(0.67 \times 0.5 \times 0.13 \lambda^{3})$
.