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
wire, rod, PCB track
or a combination of these
F
Whip antenna
length(mm) = 71250 / freq(MHz)
35-40 turns wire spring
length 120mm, dia 10mm
R
F
trim wire length or expand coil for
best results
Helical antenna
track width = 1mm
min. area 500mm2
RF
capacitors may be variable or fixed
(values depend on loop dimensions)
Cmatch
C
tune
RF GND
Loop antenna
Figure 7: Antenna types
Ordering Information:
Part No.
Description
Frequency band
(MHz)
RF power
(mW)
Channel spacing
Data rate
kbps
(kHz)
LMT1-173-5
LMR1-173-5
LMT1-151-5
LMR1-151-5
Transmitter 173.225 - 173.325 10
Receiver 173.225 - 173.325
Transmitter 150.825 - 152.450 100
Receiver 150.825 - 152.450
25
25
25
25
5
5
5
5
LMT1-173-5-12k5 Transmitter 173.225 - 173.325 10
LMR1-173-5-12k5 Receiver 173.225 - 173.325
LMT1-151-5-12k5 Transmitter 150.825 - 152.450 100
LMR1-151-5-12k5 Receiver 150.825 - 152.450
12.5
12.5
12.5
12.5
5
5
5
5
LMT1-173-10
LMR1-173-10
Transmitter 173.225 - 173.325 10
Receiver 173.225 - 173.325
25
25
10
10
LMT1-xxx-5
LMR1-xxx-5
Where xxx is any 2MHz band
from 130MHz to-180MHz
10/100
25
25
5
5
Radiometrix Ltd
LMT1/LMR1 Data Sheet
page 9
RADIOMETRIX [ RADIOMETRIX LTD ]
