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

This communication presents a low-profile, wideband, andhigh-gain X-band low temperature cofired ceramics (LTCCs) phasedarray antenna (PAA). The overall profile is only 2.4 mm that is around0.12 lambda(lambda is the free space wavelength at the highest working frequency)based on element sizes of 14.3x18.2 mm (0.57 lambda x0.73 lambda) and a wideoperating frequency bandwidth achieved by loading the matching viasbetween the patches of the dipole arms and the ground. The equivalentcircuit model (ECM) of this element is given to comprehensively analyzethe function of the matching vias to extend the impedance bandwidth.To further improve the scanning performance of the PAA, metal wallsaround the dipole patches and choke grooves on the substrate areintroduced. Thus, the loop-mode resonance and surface waves that causeddeterioration of the active voltage standing wave ratio (VSWR) nearthe lowest and highest operating frequencies are suppressed. To achievehigher gain, the proposed antenna element is compactly arranged with alarger distance (0.57 lambda x0.73 lambda) to construct an 8x8 array integrated inan LTCC package and the maximum gain at the highest frequency canreach 23.7 dBi. Moreover, the array can achieve a good beam scanningcapability over a wide band of 40% with a maximum scanning angle up to +/- 45 degrees(around 92.9% of the theory limit) in H-plane and +/- 20 degrees(around91.2% of the theory limit) in E-plane. Meanwhile, the active VSWRsalmost always remain below 2.5, enabling perfect impedance matchingwhen scanning at all angles. With these advantages, the proposed designhas potential for application in satellite communication systems.