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Yagi FM 9
G = 9.5 dB
Yagi design frequency =98,00 MHz
Wavelength =3059 mm
Parasitic elements contacting a square section metal boom 25 mm across.
Folded dipole mounted same as directors and reflector
Director/reflector diam =7 mm
Radiator diam =10 mm
REFLECTOR
1505,0 mm long at boom position = 30 mm (IT = 740,0 mm)
RADIATOR
Single dipole 1447,7 mm tip to tip, spaced 612 mm from reflector at boom posn 642 mm (IT = 711,5 mm)
Folded dipole 1484,6 mm tip to tip, spaced 612 mm from reflector at boom posn 642 mm (IT = 730,0 mm)
DIRECTORS
Dir Length Spaced Boom position IT Gain Gain
(no.) (mm) (mm) (mm) (mm) (dBd) (dBi)
1 1389,9 229,4 871,3 682,5 4,8 6,9
2 1377,3 550,6 1421,9 676,0 6,5 8,6
3 1365,6 657,7 2079,6 670,5 7,8 9,9
4 1354,9 764,8 2844,4 665,0 8,9 11,0
5 1344,8 856,5 3700,9 660,0 9,8 11,9
6 1335,6 917,7 4618,7 655,5 10,5 12,7
7 1327,0 963,6 5582,3 651,0 11,2 13,3
COMMENTS
The abbreviation "IT" means "Insert To", it is the construction distance from the element tip to the edge of the boom for through boom mounting
Spacings measured centre to centre from previous element
Tolerance for element lengths is +/- 9 mm
Boom position is the mounting point for each element as measured from the rear of the boom and includes the 30 mm overhang.The total boom length is 5612 mm including two overhangs of 30 mm
The beam's estimated 3dB beamwidth is 44 deg
A half wave 4:1 balun uses 0,75 velocity factor RG-6 (foam PE) and is 1147 mm long plus leads
FOLDED DIPOLE CONSTRUCTION
Measurements are taken from the inside of bends
Folded dipole length measured tip to tip = 1485mm
Total rod length =3011mm
Centre of rod=1506mm
Distance BC=CD=717mm
Distance HI=GF=710mm
Distance HA=GE=749mm
Distance HB=GD=788mm
Distance HC=GC=1506mm
Gap at HG=15mm
Bend diameter BI=DF=50mm
If the folded dipole is considered as a flat plane (see ARRL Antenna Handbook) then its resonant frequency is 96,1MHz and K is 0,952
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