An absorption wavemeter for the decimetre region

An absorption wavemeter is described which can, by suitable design, be constructed to cover any frequency band in the decimetre region. Sensitivity and selectivity are satisfactory, the construction is simple and avoids any skilled workshop technique. Resonance is indicated by a microammeter operated from a crystal rectifier. A model was actually constructed for 470¿500 Mc/s, on which frequency can be read to ±0.5 Mc/s. The Q-factor of an unplated brass model was 590, but silver plating increases the Q-factor considerably.