VK5DJ's YAGI CALCULATOR
Yagi design frequency =1478,64 MHz
Wavelength =203 mm
Parasitic elements contacting a square section metal boom 15,00 mm across.
Folded dipole mounted same as directors and reflector
Director/reflector diam =4 mm
Radiator diam =2 mm
REFLECTOR
109 mm long at boom position = 30 mm (IT = 47,0 mm)
RADIATOR
Single dipole 94 mm tip to tip, spaced 41 mm from reflector at boom posn 71 mm (IT = 39,5 mm)
Folded dipole 108 mm tip to tip, spaced 41 mm from reflector at boom posn 71 mm (IT = 46,5 mm)
DIRECTORS
Dir Length Spaced Boom position IT Gain Gain
(no.) (mm) (mm) (mm) (mm) (dBd) (dBi)
1 95 15 86 40,0 4,8 6,9
2 94 36 122 39,5 6,5 8,6
3 92 44 166 38,5 7,8 9,9
4 91 51 217 38,0 8,9 11,0
5 90 57 273 37,5 9,8 11,9
6 89 61 334 37,0 10,5 12,7
7 89 64 398 37,0 11,2 13,3
8 88 67 465 36,5 11,7 13,9
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 +/- 1 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 495 mm including two overhangs of 30 mm
The beam's estimated 3dB beamwidth is 41 deg
A half wave 4:1 balun uses 0,66 velocity factor RG-174 (PE) and is 67 mm long plus leads
FOLDED DIPOLE CONSTRUCTION
Measurements are taken from the inside of bends
Folded dipole length measured tip to tip = 108mm
Total rod length =240mm
Centre of rod=120mm
Distance BC=CD=42mm
Distance HI=GF=39mm
Distance HA=GE=59mm
Distance HB=GD=78mm
Distance HC=GC=120mm
Gap at HG=5mm
Bend diameter BI=DF=25mm
If the folded dipole is considered as a flat plane (see ARRL Antenna Handbook) then its resonant frequency is less than the flat plane algorithm's range of 10:1
Pierwszy raz będę robić antenkę i proszę was byście mi trochę pomogli. To obliczyłem na szybko, na pewno będą tam bardzo duże błędy. Użyłbym 2 mm drut. Do tej antenki będzie potrzebny 50 ohm przewód czy 75 ohm. Dziękuję
