A Low-Profile LTCC Phased Array Antenna With Wideband and High-Gain for X-Band Satellite Communications

This communication presents a low-profile, wideband, and high-gain X-band low temperature cofired ceramics (LTCCs) phased array antenna (PAA). The overall profile is only 2.4 mm that is around <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.12\lambda $ </tex-math></inline-formula> (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> is the free space wavelength at the highest working frequency) based on element sizes of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$14.3\times 18.2$ </tex-math></inline-formula> mm (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.57\lambda \times 0.73\lambda $ </tex-math></inline-formula>) and a wide operating frequency bandwidth achieved by loading the matching vias between the patches of the dipole arms and the ground. The equivalent circuit model (ECM) of this element is given to comprehensively analyze the function of the matching vias to extend the impedance bandwidth. To further improve the scanning performance of the PAA, metal walls around the dipole patches and choke grooves on the substrate are introduced. Thus, the loop-mode resonance and surface waves that caused deterioration of the active voltage standing wave ratio (VSWR) near the lowest and highest operating frequencies are suppressed. To achieve higher gain, the proposed antenna element is compactly arranged with a larger distance (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.57\lambda \times 0.73\lambda $ </tex-math></inline-formula>) to construct an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> array integrated in an LTCC package and the maximum gain at the highest frequency can reach 23.7 dBi. Moreover, the array can achieve a good beam scanning capability over a wide band of 40% with a maximum scanning angle up to ±45° (around 92.9% of the theory limit) in H-plane and ±20° (around 91.2% of the theory limit) in E-plane. Meanwhile, the active VSWRs almost always remain below 2.5, enabling perfect impedance matching when scanning at all angles. With these advantages, the proposed design has potential for application in satellite communication systems.