When I was in radio school we cut a removed from service co linear antenna in half.
I was surprised when I seen how simple the innards were.
These type of antennae are usually vertical polarized and depending on the number of sections, can really squeeze the pattern flat to the horizon with resulting gain.
This PDF has a simple design using sections of coax soldered together in an alternating fashion.
73
Mike N0QBH
N0QBH Mike Berg