Chapter 8
Antenna
8.1 Introduction
In order to compens ate huge propagation loss of THz signal, a nd realize wide-
band and high s ensitivity receivers, effective THz imaging/communication sys-
tems also req uire antenna an antenna array with high-direc tivity ra diation
pattern [229] and high e fficiency with sufficient bandwidth, which imposes
grand challenges for an on-chip antenna design in CMOS. Firstly, the realiza-
tion of highly directive radiation is not trivial. The conventional right-handed
antennas (patch, dipole and etc.) [230, 32] have a positive phase-and-length
relation that usually results in non-in- phase radiation and large-sized design.
Secondly, due to close distance between the top metal layer and ground, the
radiation efficiency of on-chip antenna is not high. Moreover, each antenna
element must be as compact as possible to form antenna array in limited chip
area. The previous on-chip antenna works [32, 230, 90, 231] have either low
gain or narrow bandwidth and ignored the polarization issue. For example,
given the THz source with linearly polarized radiation, the longitudinal polar-
ization may be turned into transverse direction after penetrating through the
tissue [16]. If the antenna at the receiver is also linearly polarized, the detec-
tion efficiency may be largely reduced due to the mismatch in the polarization
directions.
On-chip antennas have more stringent requirements on the antenna size
than the off-chip ones. They are us ually implemented at a frequency higher
than 200 GHz, for which a structure with equivalent electrical length of λ/4
or λ/2 can be fit into the chip scale with good efficiency.
In this chapter, two types of on-chip antennas are proposed to deliver both
high gain and compact size. In the first pa rt, the on-chip THz leak y wave an-
tenna (LWA) design is explored with periodic composite right/left-handed
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