The antenna choice and position directly controls the system range. Keep it clear of other metal in the
system, particularly the 'hot' end. The best position by far, is sticking out the top of the product. This is
often not desirable for practical/ergonomic reasons thus a compromise may need to be reached. If an
internal antenna must be used, try to keep it away from other metal components, particularly large
ones like transformers, batteries and PCB tracks/earth plane. The space around the antenna is as
important as the antenna itself.
410mm @ 173MHz
R
F
Whip antenna
wire, rod, PCB track
or a combination of these
length(mm) = 71250 / freq(MHz)
R
F
Helical antenna
35-40 turns wire spring
length 120mm, dia 10mm
trim wire length or expand coil for
best results
RF
C
tune
C
match
RF GND
track width = 1mm
2
min. area 500mm
capacitors may be variable or fixed
(values depend on loop dimensions)
Loop antenna
Figure 7: Antenna types
Ordering Information:
Part No.
LMT1-173-5
LMR1-173-5
LMT1-151-5
LMR1-151-5
LMT1-173-5-12k5
LMR1-173-5-12k5
LMT1-151-5-12k5
LMR1-151-5-12k5
LMT1-173-10
LMR1-173-10
LMT1-xxx-5
LMR1-xxx-5
Description
Transmitter
Receiver
Transmitter
Receiver
Transmitter
Receiver
Transmitter
Receiver
Transmitter
Receiver
Frequency band
(MHz)
173.225 - 173.325
173.225 - 173.325
150.825 - 152.450
150.825 - 152.450
173.225 - 173.325
173.225 - 173.325
150.825 - 152.450
150.825 - 152.450
173.225 - 173.325
173.225 - 173.325
RF power
(mW)
10
100
Channel spacing
(kHz)
25
25
25
25
12.5
12.5
12.5
12.5
25
25
25
25
Data rate
kbps
5
5
5
5
5
5
5
5
10
10
5
5
10
100
10
Where xxx is any 2MHz band
from 130MHz to-180MHz
10/100
Radiometrix Ltd
LMT1/LMR1 Data Sheet
page 9
RADIOMETRIX [ RADIOMETRIX LTD ]
