A pole can be made at home, very easily. (if you know how)
You just need to get pipes from scrap metal, or in a worse case, you can buy them.
The first comfortable and non-anchored pole can be a discarded street lamp, the bigger, the better. The best is a ready-made lamp from the railway, complete with steps.
Also good are those that occur on the exits from the city, which carry 2 lamps on the upper 'Ypsilon'. Two such poles can be assembled into a non-anchored pole of 22m; just extend the last piece, or weld 2-3 pipes on the outside to prevent torsional movement, or thicker rebar, or scraps of strip steel, sheet metal thickness 15-25mm.
Steps can be welded from rebar or, as needed, also from pipes.
The load capacity will be deeply underestimated because the end Ypsilon with lamps weighs about 180kg, and the torsional pressures in the wind are much greater than what a rotator with a small antenna can handle. Usually, in extremely strong winds, the antenna elements will fly off first, then the boom, and in between, it will tear the brake off the rotator.

However, a very deep and strong concrete foundation with a welded network structure using significantly thicker pipes must be used for the construction, into which the entire pole will be inserted.
The problem will be raising it if a truck crane is not available.
Of course, it is possible, but if you haven't worked on a lamp post and don't have the tools for constructing a supporting 'X' and a winch, you probably won't get it into that cemented pipe.

The second type is a quasi-truss welded pole made of pipes, where 3 thicker pipes are welded together, and in the center, as a spacer insert, pieces of the same diameter pipe about 20cm are welded with a gap of about 70cm.
In cross-section, imagine it as a flower with three petals and a center.
Such a structure is very resistant to torsional oscillations in a non-anchored pole.
If you want to build to a height of about 15m, you should divide such a pole into 3 equal parts, with the bottom part having a foundation in concrete at least 2m deep.
The foundation should consist of at least 50mm (2″) water pipes, the second stage 1.5″ and the last 1″

Galvanized pipes can also be used, but they are very difficult to weld due to galvanization; the weld area must be ground or welded using WIG/TIG.

If you want to have very strong reinforcement, it can be threaded from the outside with roxor partitions.

For all these constructions, you just need a garden, an electrical connection, a large angle grinder, and a strong unidirectional welder (150A), a few packs of basic electrodes, a little time, a few friends for construction, supports for leveling, a construction winch.. a mixer will help a lot.

From practice for practice, but it is better to use a classic lattice mast, or a smooth, ready-made one, have it installed by electricians, it won't be expensive and it's a quick build, only the price will be higher than for a DIY construction.

For example, in Bratislava, all the traction support lattice masts are currently being replaced at the main station, I think it won't be a problem to agree.

It is good to have a building permit for peace of mind.
As a reason, you need to state the need to have a mast for your own public lighting in the garden on the building application, the type and number of the mast, the type of lamp according to what they currently have in scrap metal, or at the lamp factory near your residence, usually all documentation and building plans, as well as situational plans, and if necessary, the stamp of the contractor can be obtained at the district lamp factory for plum brandy, if you are lucky.
They won't give you big problems at the building office if everything is properly documented from the usual building agenda of the public lighting company, railways, etc.
See according to the area of construction.
http://www.zoznam.sk/katalog/Sluzby-remesla/Komunalne-sluzby/Verejne-osvetlenie/

Well, yes, but if you take that you put 'just a pipe' in the garden without anchoring, then the minimum is a 50mm water pipe in a distribution length of 6m, which can possibly be obtained or welded from two more transportable 4m pieces, has serious deficiencies...

The problem without anchoring with a load at the end of the rotator+antenna (about 18-30kg plus or minus I estimate) will have a swing of 80cm at the end and torsional oscillation of about 2 degrees.
That wouldn't seem to matter, but from a structural point of view, that pipe is not designed for that, it's soft iron that will gradually bend like iron barbed wire.

Another problem will be that lifting it with the antenna will not be easy, it must have at least a good ladder, or supporting X and a winch, because without that it cannot be lifted easily, it requires a lot of hands.
The foundations must also be solid.
If you just erect a 50mm pipe in the garden and try to add a ladder 5m high to it, climb on it and install the antenna at the top, you will immediately find that it is unstable and wobbles, bends under the weight of the system, etc.

The result will be a shaky and swaying pipe with a low antenna in the garden, where the time spent installing, work with transport, and effort in construction =
=the same plus 20% on top and there is a street lamp installed with welded steps, or at least hooks for placing a horizontal ladder, which will withstand the weight of stacked antennas without anchoring.

Even for a similar price, if not less, a solid installation can be made into a pre-concreted pit with stones expected with concrete, a homemade concrete installation for a telegraph or electric wooden pole, which is screwed in, normally a new one can be bought at a height of 6m.. (it's better to have it installed for a few bottles and some old stuff)
If it is painted with tar from time to time, or tar is sprayed on the through screws to the concrete I profile where the pole is screwed, it will last for ages, without claiming any demanding constructions.
No building permit is needed for that, it was simply there and that's it.
It can carry the given antenna without problems.

I have seen such poles even 10m high, but I would already be scared to climb that with steps.

Then it is easier not to build anything permanently, but to put a magirus there, properly anchor it, and just pray that the brown Slovaks don't take it away like a metal deposit.