QFH ANTENA 137MHz SATELITE METEOROLOGICO

 
QFH ANTENA 137MHz SATELITE METEOROLOGICO
BATEDOR DE OVOS
http://jcoppens.com/ant/qfh/calc.en.php




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ANTENA QFH

consulta ao site do Mestre Roland Zumerli PY4ZBZ

MAIO DE 2023
trabalho no cefet rj sobre recepcao de satelites meteorologicos em 137MHz
montagem da antena qfh de tubos de cobre 9mm (3/8")


Sandro Almeida 2B ELT 2023, Gabriel Dourado 2B ELT 2023, Omar 3B ELT 2023 e eu, Aridio.

















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http://www.g4ilo.com/qfh.html

A QFH antenna for the weather satellite band







































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CALCULO DA ANTENA QFH

Input the data

Thanks to suggestions of Kevin and Barry Fittler, and the insistence of many others, I've finally made a bit of time to do 'repair work' on the calculator. Please report problems, if any.

Design frequencyMHz
Number of turns (twist)
Length of one turn wavelengths
Bending radiusmm
Conductor diametermm (optimum: 20.5 mm)
Width/height ratio

Results

Wavelength2181.8 mm
Compensated wavelength2336.7 mm
Bending correction6.4 mm

Larger loop

Total length
2397.4 mm
Vertical separator
889.6 mm
Total compensated length
2423.2 mm
Compensated vertical separation
859.6 mm
Antenna heightH1=731.8 mm
Internal diameterDi1=315 mm
Horizontal separatorD1=322 mm
Compensated horiz. separationDc1=292 mm

Smaller loop

Total length
2278.3 mm
Vertical tube
845.8 mm
Compensated total length
2304 mm
Compensated vertical tube
815.8 mm
Antenna heightH2=695.8 mm
Internal diameterDi2=299.1 mm
Horizontal separatorD2=306.1 mm
Compensated horiz. separatorDc2=276.1 mm

Generate a drilling template

To generate a drilling template in PDF form, please enter the following extra data:

Vertical support tube diameter: mm
Horizontal support tube diameter: mm
Select paper size:
For more information on the construction technique corresponding to this template, visit this page.

Legend

This calculator generates a lot of data! Take care in the use of the information in order not to make mistakes...

Here's a little explanation:

Design frequency
Evident?
Number of turns (twist)
What's the twist of the antenna? (normally 0.5 (180 degrees)
Length of one turn
A few variations of the antenna exist. Normally the circumference (length of the loop) is 1 wavelength, but 1.5 wavelength and 2 wavelength versions exist.
Bending diameter
As it's impossible to bend the corner abruptly at 90 degrees, this value is needed for the calculations. It's measured from the bending center to the center of the tube.
Conductor diameter
External diameter of the tube or coax cable.
Diameter/height ratio
Most frequently this ratio is 0.44, but slightly lower values (0.3 to 0.4) give better horizon coverage.
Wavelength
Wavelength, corresponding to the selected frequency.
Compensated wavelength
Wavelength, compensated according to the conductor diameter.
Bending correction
Correction value needed according to the bending diameter.
Total length
Total length of the loop, before compensation.
Total loop cmpensated length
Total length of the loop, compensated for the bending effect, and the fact that the loop must be slightly larger (or smaller). This is the amount of tubing necessary for this loop.
Compensated vertical separation
Vertical separation (without the 'bends').
Compensated horizontal separation
This is in fact the horizontal part without the 'bends', and corresponds to the horizontal pipe necessary to support the cable.
Antenna height
Height of the loop (twisted!).
Internal diameter
The diameter of the (imaginary) cylinder on which the loop would be wound.
(c) John Coppens ON6JC/LW3HAZ










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