Broadband and High-Gain Embedded Probe-Fed Low-Profile High-Order-Mode Antennas

In this communication, a low-profile high-order-mode (HOM) antenna fed by an embedded L-shaped probe is proposed for high gain and broadband operation. Mode distribution in this low-profile cavity is studied. Three feeding structures, including substrate-integrated waveguide (SIW), probe, and embedded probe, are discussed thoroughly regarding their effect on the HOM cavity. The quasi-metasurfaces (MTS) are introduced to suppress the performance deterioration of the proposed antenna. The mode
$TE_{810} $
is excited over a wide bandwidth for improved radiation. The study shows that the proposed metasurface antenna achieves a gain of 12 dBi and a
$|S_{11}|\leqslant - 10$
dB bandwidth of 35.8% (4.7–6.75 GHz) with an area of
$1.14\times 1.14\,\, \lambda _{0}^{2}$
, where
$ \lambda _{0}$
is the free-space wavelength at the center frequency of 5.72 GHz. In particular, the proposed HOM-fed antenna features a very low profile of 0.045
$ \lambda _{0}$
.