Using polarization modulation of radio waves can imply a broad frequency spectrum, depending on the rate of polarization change, even if the carrier frequency and amplitude remain constant. A spectrum analyzer with a constant polarization antenna may detect sidebands similar to amplitude modulation. It's essential to check FCC regulations regarding frequency use, as certain bands permit spread spectrum emissions with specific restrictions. For experimentation, obtaining an amateur or experimental license is advisable. Direct inquiries to the FCC can provide further clarification on regulations and licensing.