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ANTENTOP- 03- 2003, # 004

Half-Loop Antennas

 

 

 

 

V APPLICATIONS The chart below present the "not so wellknown" specificities and applications of the HF tuned HF/125W loops and half-loops.  
     

GENERAL CHARACTERISTICS

 

APPLICATIONS

 

 

Very small dimensions for HF (1.5 to 3m rectangle or diameter)

Can be radomed

 

 

Difficult installations (on roof, small areas, ship,...)

Half-loop capability to communicate from a moving vehicle.

Discrete stations (fixed and mobile)

 

 

Small surface on ground.A ground plane is not necessary for loop

 

 

Easy and low cost installation.

 

 

 

Low take-off angle propagation andGround wave radiation (8-shaped pattern)+Near Vertical Incidence Skywave (NVIS)

Directivity: + 2dB in free space and +5dB or +6 dB on a conductive ground Gain: - 12/-15 dBi at lowest frequencies to+ 2/+ 5 dBi at highest frequencies.

 

 

Communications up to 1000km with 125W, without silent zone in azimuth nor petal nulls in elevation.

Communications of the ships along the coasts and over mountains.

One antenna only gives the equivalent services of a NVIS antenna (like horizontal dipole) and a vertical whip (at longer ranges).

Achievement of an ALE fully automated mobile station: no more need to change antennas at halt alongside the classic silent zone of whips.

 

 

 

High selectivity in the lowest range.

High reduction of outband transmissions.

High reduction of received noise and improvement of the Signal/Noise ratio(typically 6 to 10dB in reception compared to the wider band antennas like tuned whips or dipoles)

High rejection of the strong wideband signals like high voltage lines spurious, indirect effects of lightening, etc...

2 tuned loops are highly isolated (particularly when they are perpendicular with one frame in the central axis of the other one).

 

 

 

 

 

Compared to the whip antennas: Better listening comfort, reduced Bit Error Rate (BER) of data transmissions or FH synchronisation signals. Extra filters can be avoided in many applications.

Operational in industrial zones and areas of frequent lightning.

Simultaneous transmission and reception on the same narrow site (head of a star chained network, duplex station, HF-HF relay,...)

 

 

Fully capacitive tuning unit, without coil nor magnetic signature effect

 

 

Interesting for certain ships

 

 

HF/125W fast tuned frame antennas can find a number of applications for point to point, ground to air and ship to shore applications at any distance to 1000 km.

 

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August 7, 2016 20:38

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