ARLA/CLUSTER: HF multiband beam "MARÍA MALUCA"

[Carlos Fonseca - CT1GFQ]

HF multiband beam "MAR�A MALUCA"

Published as an article on URE's magazine "Radioaficionados" on January 2009



    Invented by José Salvador Luiz Victor Marinaro (PY2BBP) in 1957, this antenna is more than a dipole, it is a dipole with a passive element which works as a director or reflector element so there is a directional gain. Works from 20 to 6 meter bands. In 12, 10 and 6 meter the passive element works as reflector instead of director, then a 180º rotation is needed to work the same direction.



         

   

    To build the elements can be used aluminium pipes of several diameters, linked and fixed by screws, to get the needed lengths. The dipole stands its two parts by a pvc pipe and a methacrylate plate.



                                                    



    To feed this antenna a 450Ω ladder line is needed and antenna tuner too. Also a BALUN is needed which can be 1:1 or 4:1. Mine is a 1:1 current BALUN wound on a FT-240-43 core (12 bifilar turns).



                                                                         



    Ladder line length is important because according to the length you cut it and frequency, impedance values can be so high than the tuner cannot match. Minimum length is about 13.7 meters. Then I added a RG-213 to reach my radio room. This length must be also adjusted to be matched by the tuner with SWR 1:1. The following diagram shows the instalation.







    The ladder line must be insulated from metalic objects about 15 to 20 cm. Can be replaced by two parallel RG-62 (93Ω) coaxial cables, then feed line will be 186Ω.  

  



                                             

    Map shows contacts I made when testing the antenna "Maria Maluca". In black color are 20 meter band QSOs, blue are on 17m. and red are on 15m. Mode was BPSK31 in all contacts, power 30-40W. The 80% of QSOs reported RST 599.

                                            







Technical data:

Bands:                        20, 17, 15, 12, 10 y 6 meter

Gain:                         7.26 - 2.25dBi

Front/Back relation (F/B):    6.63 - 0.48dB

Bandwidth @ SWR 2:1:          20m.: 135kHz

    17m.: >100kHz

    15m.: 260kHz

    12m.: >100kHz

    10m.: 390kHz

Max power:                    1000W

Boom length:                  1.46 m.

Longest element:              7.56 m.

Turning radius:               3.9 m.

Windload:                     0.2 m² 

Weight:                       3.6 kg


http://perso.orange.es/isaac.dg/antena%20maria%20maluca.htm

73's de Carlos CT1GFQ
SKCC#466
REP#1406
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