I removed the elements for 21MHz and 28MHz and used them as a single element. Since 15m+10m=25m, it should be resonant somewhere around 12MHz.
At 7026kHz, the measurement using a bridge tells that V1=2.569 V, V2=0.869 V, and V2delay=24.20 nS, which means Z=2.629+j8.624 ohm, and SWR=19.6.
Considering the cable length of 20m, Zant=14.861-j108.951 ohm.
At 10110kHz, V1=3.083 V, V2=5.222 V, and V2delay=4.40 nS, which gives Z=54.274+j131.008 ohm, and SWR=8.20, and Zant=29.910+j95.210 ohm.
At 14010kHz, V1=2.599 V, V2=2.495 V, V2delay=-9.40 nS, which gives Z=8.131-j30.425 ohm, and SWR=8.47, and Zant=5.906-j1.093 ohm.
For stub matching at 7026kHz, we need a 3490.4 mm cable and a 962.6mm short-circuited cable both 75 ohm to obtain Z=49.383+j0.774 ohm.