Antennas can be combined ONLY under LIMITED conditions:
For ALL frequencies of interest, they must match in phase and amplitude. This is done by people who know radio frequency engineering well, and will hurt performance if you don't kno what you're doing.
This makes your attempt very risky. You'll likely add multipath interference with adding the second antenna.
Try a rotater on your big antenna?
Or switch between the two antennas, A/B switch?
I am an RF engineer, and I do know how to combine antennas. It is not trivial. You get two antennas of the same model, put a low noise preamp on each one at the antenna, use coaxial cables of identical length into a splitter used in reverse as a combiner, and the single output goes to the TV.
The antennas must be on the same mast, pointed the same direction, and at the proper distance apart (~wavelength/2.) And, this will only add 3 dB (2x) signal for all the work and expen$e. The preamps (not cheap for quiet ones) are used to ensure cable and combiner losses don't negate the hard work to do this.