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FM Transmitter Module
Application Information
Antenna Design
The design and positioning of the antenna is as
crucial as the module performance itself in achieving
a good wireless system range. The following will
assist the designer in maximising system
performance.
The antenna should be kept as far away from
sources of electrical interference as physically
possible. If necessary, additional power line
decoupling capacitors should be placed close to the
module.
The antenna ‘hot end’ should be kept clear of any
objects, especially any metal as this can severely
restrict the efficiency of the antenna to receive power.
Any earth planes restricting the radiation path to the
antenna will also have the same effect.
Best range is achieved with either a straight piece of
wire, rod or PCB track @ wavelength (15.5cm @
433.92MHz). Further range may be achieved if the
wave antenna is placed perpendicular in the middle
of a solid earth plane measuring at least 16cm radius.
In this case, the antenna should be connected to the
module via some 50 ohm characteristic impedance
coax.
Helical Antenna
MKT5-XXX
Version 3.0
Page 4 of 5
Advancing radio solutions from 100 to 1000 MHz
We manufacture high quality transmitters, receivers and transceivers
Application Circuit
The application circuit shows how the MKT5 transmitter
can easily be integrated into a system to form a wireless
link
T5
A0
A1
A2
A3
A4
A5
A6
A7
VSS
AD8
AD9
AD10
AD11
TE\
OSC2
OSC1
DOUT
VDD
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
HT12E
R
OSC
+5V
4
5
1
2
3
+5V
ANTENNA
Figure 3: MK Transmitter Application Circuit
RF
RF
Whip Antenna
34mm @ 433MHz
17 turns equally spaced
= 5mm (inside)
15.5cm @ 433MHz
Figure 2: Antenna Configurations To Be Used
With The MKT5 Transmitter Modules