Description
Technical parameters
Design details
B P L U S T V a . s .
B PLUS TV a. s., Po
ž
árnická 140, 742 83 Klimkovice, Czech Republic
phone: +420 556 420 360, fax: +420 556 420 301
e-mail: [email protected], http://www.btv.cz
MLA-M
Frequency range
Input impedance
Max. power
SWR after tuning
Input connector
Dimmensions
Weight of antenna
Diameter of the loop
630 x 750 x 180 mm
PL
3,5 - 28 MHz
10 W
1:1; max. 1:1,2
2,6 kg
600 mm (<2ft)
50 Ohm
page 1
MLA-M
Magnetic Loop Antenna MLA-M supplied by the BTV corporation (http://www.btv.cz ) is „plug and play“
type product. Antenna is given up to the QRP service on all HF radioamateur bands except for the 160 m. In
spite of the fact, that the diameter of the MLA is only 60 cm (less than 2 ft), it is possible to use this antenna
with minimalistic design for communication on 8 HF bands 3,5, 7, 10, 14, 18, 21, 24 and 28 MHz.
In the case of small magnetic loop antenna you can not suppose the same efficiency in transformation of HF
current into HF (electro)magnetic field as for let`s say half-wave dipole. Power loss is min. abt. 10 dB. But
antenna MLA-M is supposed to be acceptable compromise which enables to carry on the radioamateur hobby,
not only for portable QTH, but for example in condominium with restricted possibilities of building classic
antennas, in conservation urban areas etc.
MLA-M is ideal for the communication through digital modes with sofisticated protocoles convinient for very
low signals. The loss of abt. 10 dB due to using indoor antenna is in comparison with another influences of
ionosphere atc. negligible.
Perfect impedance adaptation of the antenna in all HF radioamateur bands from 3,5 to 28 MHz is achieved
by the industrial protected solution developed by the corporation BTV. Point of such wide range of tuning of
magnetic antenna is based on two-turns construction of the main antenna circuit inductivity with the
possibility of partly short-circuiting see fig. 1-3.
Possible switching of the antenna
1. Mode 3,5 MHz
Loop consists of two turns, jumper J1 is switched off and the
jumper J2 connecting parallel capacity is switched on, see fig. 1.
2. Mode 7-10 MHz
Loop consists of two turns, jumper J1 is switched off and the
jumper J2 connecting parallel capacity is switched off, see fig. 2.
fig. 1
fig. 2
J2
J2
J1
J1
