Constructing Simple VHF Dipole Antenna: Cable Interference, Antenna Shortening & 149 MHz 5/8 Wave

Hello
I'm starting to build a simple transmit / receive VHF dipole. I came across the construction www.marph.pl/sq3mve/sprzet_anteny.php
Vertical dipole 1/2 ?. I mean the structure itself, will the cable running along the antenna not interfere with the signal while transmitting? The second question that bothers me is a plastic tube in which the antenna would be ultimately mounted. How will it affect the operation of the set and what will be the antenna shortening factor? The antenna is to be at the exact frequency of 149 MHz 5/8 wave mounted on a tower about 11 meters above the ground, about 9 meters of radio cable.
Thank you very much for any additional information.

My colleague MVE with the proposal of a dipole made in this way probably took some time.
Look for another "more normal" proposal for execution if you have a problem with figuring out what and how to put it together so that it is efficient, tight and correct.

I make a dipole from 8-10mm aluminum tubing, an electrical box and a 1/2 "section of PVC tubing from cold water as a carrier (horizontal element) inside which an antenna cable can be led. This horizontal element should be 1 / 2? long, but if you do 1 / 4, you will not notice any difference in the antenna operation anyway, but the dipole will certainly work better than the proposed one, where the lower arm runs parallel to the antenna cable.
You can make a balun on this horizontal pipe by wrapping it around several turns of the antenna cable.
Rather, follow this construction
Link

I have almost the entire structure ready so there is no problem with my own idea. I did not add information in the post that the antenna is to be made of copper pipes, the whole thing would be almost 2.5 meters high. It would be more convenient for me to release the cable inside, as it was done in that project, and stuff everything into one tube. So with your help it turns out that it is not worth putting in one tube, but making an elbow and after the problem

As you need a normal straight vertical antenna, then make a Slim Jim or a J-type copper wire on a PVC pipe, or from a 300Ohm symmetrical cable, or solder a 15mm copper tubing.
There is also something called a sleeve dipole, but the bottom tube should have a diameter clearly larger than the diameter of the power cable, if I remember correctly, it must be at least 4x the diameter of the cable that you will use to power this antenna.
The construction can be found in 5 seconds on googles, so I do not paste the links.