Frequency hopping does not come without challenges ~ and it is more of a means to prevent eavesdropping than a means to conceal location. The days of the Realistic police scanner are gone. With moderately capable test equipment becoming cheap enough for the radio enthusiast, if you transmit, you can be found. And with frequency hopping, the frequencies are not in the same band so now you will need multi-band antennas with the same radiation pattern on all bands.
Anyone with a spectrum analyzer can drive around and find where the signals get stronger, even if they are not tuned into and listening to any of them. In fact, I was just watching the signals from my phone pop up on the spectrum as I was texting a friend yesterday. Yagi's are ok for VHF and UHF foxhunts but I think doppler shift and TDOA interferometer techniques are easier for VHF frequencies. Adcock arrays's and variable phase antenna arrays (like using a radio goniometer), are great for HF. The null of a bar antenna or loop antenna is very sharp, just like the adcock, sharper than the main lobe by far. Same applies to many antennas so by using a balanced loop antenna etc, you can get a very accurate direction using the null (when the signal disappears) in the patters as opposed to the 50° to 60° 3dB directivity of a 5 or 6 element yagi.
Using VHF and UHF for local comms is ideal since those signals won't go far. NVIS is great for lower frequency HF work because it goes up and comes back down meaning that instead of a dipole at a half wavelength above ground that illuminates two directions and travels (for the most part) along the ground hitting the ionosphere 800 miles away before refracting back down, NVIS antennas near good ground (10-20 feet) illuminates a 600 mile radius with no dead zones. Locating a signal that comes from above is much harder because less people are going to try to find the angle of incidence and make predictions about the amount of ionospheric refraction and ducting to guess where you are.
Use only enough power on a band that has just sufficient propagation to get the message sent.