Low-Power 60-GHz CMOS Radios for Miniature Wireless Sensor Network Applications - Ultra-Wideband and 60 GHz Communications for Biomedical Applications - page 192

Fig. 10 The dimensions of
the 60-GHz patch antenna

Fig. 11 Radiation pattern of
the 60-GHz on-chip patch
antenna

to that of an infinite ground plane [ 25 ]. Figure 10 illustrates the final dimensions of
the patch antenna. The resonant frequency is mainly determined by the width and
length that can be verified by back calculating for f 0 from Eqs. 1-3 when W and
L are known. The 3 σ process variation parameters on length and width of the top
metal layer are on the order of 400 ppm, resulting in the same order of accuracy of
the resonant frequency of the patch antenna, determined by the first-order antenna
theory. The simulated antenna radiation pattern is shown in Fig. 11 . The simulation
results include the effects of required dummy filling for meeting local metal density
requirements, and show that the center frequency is 60.54 GHz with a bandwidth
of 920 MHz. The peak antenna gain is − 3 dB while the efficiency at resonance is

15.6 %.

Resonant Frequency Detection

Another advantage of the integrated patch antenna at 60 GHz is the ability to design
circuits that monitor the standing wave pattern along the edge of the radiator. This
allows for detecting the resonant frequency of the antenna, and ultimately using it as
a replacement for a crystal reference. To detect the resonant frequency, we will need
to understand the physical phenomena on the patch antenna when it is resonating.