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Quick Reference Guide 

Vaisala Telemetry Antenna 

RM32 

 

0611-035 

Figure 1 RM32 Antenna Assembly 

PRODUCT OVERVIEW 

This Quick Reference Guide yields a general description of the 
Vaisala Telemetry Antenna RM32 used for receiving radiosonde 
signals in the 400 MHz meteorological band. 
 

General 

Vaisala Telemetry Antenna RM32 is an antenna system intended 
to be used with Vaisala DigiCORA® Sounding System. It is 
well suited for fixed installations, but it can also be used in 
portable systems where feasible. 
RM32 has two antennas which have been selected to optimize 
the performance in all elevation angles, both near the horizon 
and at the zenith. The sounding system selects the antenna with 
the best reception through a two position antenna switch. 
 

Construction 

The Vaisala Telemetry Antenna RM32 consists of 

 

vertical antenna (1) 

 

helix antenna (2) 

 

Antenna Amplifier and Switch RAA111G (3) 

 

tubular antenna mast, tube branch and antenna cables. 

 
The numbering above refers to the figure on the cover page of 
this Quick Reference Guide.

 

 
Vertical Antenna 

The vertically polarized omnidirectional antenna performs best 
at the low elevation angles when the radiosonde is near the 
horizon. The maximum gain of 5dBi is just below zero elevation. 

 
Helix Antenna 

The helix antenna is an omnidirectional antenna with 

 

approximately hemispheric coverage with a maximum gain of 3 
dBic at the zenith. 
 

Antenna Amplifier and Switch RAA111 

All the amplifier parts are housed in a watertight box at the base 
of the antenna mast. The amplifier runs on +12 VDC voltage, 
supplied by the UHF receiver. 
 

Antenna Mast and Tube Branch 

The vertical antenna is installed on top of a tubular mast, and the 
amplifier box is mounted on the base of the mast. 

The helix antenna is attached to a flange in the tube branch. 
A mounting sleeve is provided for mounting the whole antenna 
on top of an external mast. 

INSTALLATION 

Select an installation site that is open, in other words, clear of 
obstacles such as buildings, dense forests, or high metal masts.  
 

1.

 

Fit the Antenna Amplifier and Switch RAA111G on 
the tubular mast. 

2.

 

Attach the tube branch to the tubular mast using the 
clamp included as shown in Figure 2. 

 

 

0611-037 

Figure 2 Attaching the Tube Branch to the Tubular Mast 

The distance between the antennas in the system is 
optimized to minimize mutual interference. Set the 
distance as shown in Figure 3. 

 

0611-038 

Figure 3 Distance Between the Vertical and Helix Antennas 

3.

 

Connect the vertical antenna with cables 

(DRW214802) to the ANT1 and the helix antenna to 
the ANT2 connector in the Antenna Amplifier and 
Switch RAA111G. Direct the cables through the holes 
in the antenna mast and the branch as shown in Figure 
4. 

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