MIL MFDL 0517 

Medium Wave Drive Test Antenna

 

The development of new standard such Digital Radio Mondiale (D.R.M.) on medium wave, requires to perform specific drive test in order to guarantee network quality in accordance to the international norms. Field measurements on travelling veichules, are not easy at this frequencies especially when done with electrical field antennas (eg. rods), because they ten to change the pattern depending from the ground distance and from the metal surface of the chassis, typically non ideal due the small dimensions.
The use of crossed magnetic loops antennas, avoids this issues because less sensitive to the ground capacitive effect and the reflection plane size. Due to this charapteristics, they have been largely used for years with MF and HF receivers and direction finders installed on ships and aircrafts.
MIL MFDL 0517  is an active crossed loop antenna, designed to measure the field coverage and propagation of medium wave networks (AM - DRM) and compatible to the ITU RECOMM. N° ITU-R 8S.703 (Annex 1 to Appendix 1).
The antenna consists of a couple of crossed shielded loops for HF, two independent pass band filters, two low noise amplifiers and one 90° hybrid combiner, to achieve the omni directional radiation pattern (see block diagram - picture 1). The size of the loops has been calculated to achieve the necessary gain over the noise and to permit an easy installation of the assembly onto cars and vans, allowing measurements when travelling.

More specification can been achieved by reading its complete data sheet (click to download)

                                                                                                                                       Typ. radiation pattern at 1100 KHz

 antenna circ

 

 

Schematic block diagram                                                                                                             Eg. of typ. D.R.M . receiver plot with MFDL 0517 antenna

Main Specifications 

Electrical
Frequency range 500-1700 KHz
Typ. Gain 20 dB  (a precise antenna factor table is given by default  together the technical documentation)
Typ. Return Loss 20 dB
Rejection out of the band > 30 dB @ 150 KHz
> 30 dB @ 3500 KHz
IP3 30 dBm input (measured at each singular amplifier input)
NF 9.5 dB (measured at each singular amplifier input)
Power +12 VDC @ 100mA
Connectors
DC Power MIL ST. 3 poles
RF output  N precision bulkhead female
Mechanical
Loops Diameter 600 x 600 mm
Metal box size 210W x 245L x 95 mm (IP65 - aluminium)
Weight 8 Kg
Accessories and parts delivered by default
DC Power cable (3  mt including MIL ST. connector)