ve7hj
March 19, 2020, 10:02pm
1
I have been using a 440-900 Mhz antenna from my Handheld radio. Worked but not getting a lot of tracks. I made a home made vertical half wave antenna and hung it in my porch window facing south.
Much better ! now to move it out doors and see if it gets more tracks and longer distance.
Link Ham Radio - A quarter wave groundplane antenna for your HT - YouTube
James
Half-wave antennas need to be fed from the middle. For the setup like in the picture, more appropriate is quarter wave.
Antenna Theory - Half-Wave Dipole, The dipole antenna is cut and bent for effective radiation. The length of the total wire, which is being used as a dipole, equals half of the wavelength (i.e.,
The dipole leg goes down on the other side
Anyhow … those legs look far too long for 1090 MHz.
For 1090 Mhz, the two legs put togather should be about 13.6 cm (5.3 inches), i.e.about the size of a hand
My 1090 Mhz 1/2 Wavelength Dipole With Satellite in-line Amplifier.
Click on image to see larger size
Click again to see full size
2 Likes
Oh dear.
Half wave dipole antennae do not need to be centre fed.
It is very common to feed a haflwave dipole antenna from the end.
It is frequently used in a ground independent vertical antenna for both base station and mobile use.
It is a high impedance unbalanced feed.
There have been numerous thread here about J-pole antenna which is an end fed halfwave.
S.
If you feed a 1/2 wave long wire from an end, then it is a 1/2 wave monopole whip, not a dipole. If you have provided a ground plane also, then it is still a half wave monopole, but acts like a full wave dipole.
1 Like
I don’t want to just edit my post so take out the word dipole and therefore remove the discussion about dipoles and monopoles as it is irrelevant.
I will simply restate
I also mentioned a ground independent antenna which implied that there was no ground plane.
i.e. an half wave radiating element in free space.
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abcd567:
a 1/2 wave long wire
Could you please clarify this.
Do you mean:
a 1/2 wave - long wire
a 1/2 wave long - wire
geckoVN:
Do you mean:
a 1/2 wave - long wire
a 1/2 wave long - wire
By “a 1/2 wave long wire”, I mean:
A wire whose length is 1/2 wavelength
On mobile use, the ground connection is done mostly trough human body capacitance.
1 Like
ve7hj
March 20, 2020, 3:51pm
12
Well in my haste to make my antenna I used CM instead of MM. I have now cut the elements to the correct length.
James
ve7hj:
it’s a half wave.
For what frequency?
At 1090 Mhz half wave is only 5.3 inches / 13.8 cm, while you antena in the video seems much longer than this.