Wireless Security Remote Control Development Kit User’s Guide
FIGURE 3-2:
PCB TOP LAYER PHOTO
Figure 3-3 shows the bottom layer of the PCB. The bottom layer shows the PCB loop
antenna and the PCB traces for the conductive push buttons from the plastic enclosure.
FIGURE 3-3:
PCB BOTTOM LAYER PHOTO
3.4
PCB ANTENNA DESCRIPTION
The PCB antenna is a combination of top and bottom PCB layer traces, as shown in
Figure 3-4. The feed point from the transmitter is on the right side of the figure. It is a
top layer trace shown in red. It taps into the PCB loop antenna on the bottom layer
shown in blue. The antenna loops to the left side of the PCB and is terminated to ground
by a capacitor.
The PCB antenna is an “electrically small loop antenna.” That is, the wavelength of the
antenna is very much less than the one-quarter wavelength that antennas are normally
designed to. This type of antenna has an extremely high quality factor (Q). Therefore,
it is very susceptible to parasitic impedances and very challenging to impedance match
to the transmitter.
DS41646A-page 22
2012 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
