j-poles can be very cantankerous to tune but they work well without a ground, or you could make a 1/2 wave dipole with 2 elements about 13.2" per element. mounted in PVC pipe with a tee at the center, and you can mount the dipole vertically, but you must run the feedline perpendicular to the antenna for at least a few feet. the larger the diameter of the elements, the broader the SWR match will be, but using copper pipe has a limiting factor of weight. you will notice many VHF antennas are ground plane, colinear or discone antennas for this very reason. the ground plane acts very much like a dipole with a narrow tuning range, the colinear has a little bit broader tuning range, and the discone has a very wide tuning range, because the effective diameter of the radiating element is equal to the length (biconical antennas are even better, but more difficult to make). to have a large effective diameter, the element does not have to be a solid form. many large diameter antenna elements are made with "cage" construction. shown below are a cage antenna, a biconical antenna and a discone, just to give you an idea of the construction.