Uniden 125XLT Scanner Antenna: Half Wave vs Full Wave Dipole, Distance Between Tubes, Signal Loss

Hello,

I am asking for advice.
I have purchased a Uniden 125XLT scanner and I am satisfied with it. I also made a homemade antenna for it, it's a half wave dipole.
The first question is what should be the distance between the two tubes of the dipole? I got about 1 cm, but I read that it should be 2 cm.
Is there such a thing as a whole wave dipole and does such a dipole have better parameters than a half wave dipole?
My antenna is located in the attic, I want to move it to the roof, so I will have to run about 15 m of cable, will this cable cause large losses in the signal?
Currently, I have this antenna for approx. 3 m of cable.
My question is probably trivial, but I'm not an expert on the subject :)

Regards and thank you for the answers.
Jurek

Hello, I used to have an antenna like in the attachment, calculated for the center of the frequencies that interested me.

andy014 wrote:

Hello, I used to have an antenna like in the attachment, calculated for the center of the frequencies that interested me.

Thank you for the information.
And what is the distance between the various parts of the antenna and is 15 m of cable not too much?

Greetings,
Jurek

And what antenna cable to use, 50 ohm or 75 ohm? Until now, I was convinced that it was 50 ohms, but I read somewhere that the best solution for a dipole was 75 ohms.
Please advise.
Greetings,
Jurek

jurekw88 wrote:

And what antenna cable to use, 50 ohm or 75 ohm?

Until the reception itself, it does not matter. Such a small mismatch is practically imperceptible.

And if in the future I want to transmit from this antenna, maybe I should buy and route a better fitting cable right away?
Does it also matter if 75 or 50 ohms?
I know the CB recommends 50 ohms.

Greetings,
Jurek