Miniaturized Laminated Resonator Antenna Array Loaded With Periodic Irises in LTCC

A miniaturized laminated resonator antenna (LRA) array with periodic irises is proposed in this article. By means of the distinguished slow wave property of the periodic iris-loaded waveguide (IWG), a compact LRA element with a dimension of only
$0.36\lambda _{0} \times 0.26\lambda _{0} \times 0.08\lambda _{0}$
is designed, where
$\lambda _{0}$
is the wavelength in the free space at 60 GHz. The small transverse size makes it possible to construct an antenna array with the element spacing of less than
$0.5\lambda _{0}$
, which is rather beneficial to the scanning arrays and multiple-input–multiple-output (MIMO) systems. For demonstration, a series-fed
$1\times6$
antenna array in the E-plane with the element spacing of
$0.38\lambda _{0}$
is designed and fabricated with the low-temperature co-fired ceramic (LTCC) process. The measured relative impedance bandwidth is 9.2% (from 56.3 to 61.8 GHz). The measured peak gain and 3-dB gain bandwidth are 10.6 dBi and 5.3 GHz, respectively. Furthermore, the scanning arrays are fabricated to demonstrate the scanning performance, with an element spacing of
$0.45\lambda _{0}$
in the H-plane. They support a measured maximum scanning angle of 43° while the gain drop is within 2.5 dB.