The transmitting loop will have a very sharp resonance when tuned to your frequency. It will act as a good pre-selector. In fact, you can tune your loop by listening for an increase in noise as you turn the cap. If you need more signal on receive, why not just throw out a length of wire? Very cheap, very portable. Only the transmitter needs a good VSWR match to be happy. You would just need a TR switch of some kind. Remember the old adage: 'anything less than a true dipole at least 1/4 wave above ground is going to be a compromise". That being said, an inefficient loop that is portable and easy to deploy is better than no antenna at all! I got a lot of good information about loops here: http://www.nonstopsystems.com/radio/frank_radio_antenna_magloop.htm, Frank is a very avid experimenter and nice guy if you want to contact him with a question.
