Optimum bandwidth of signal-to-noise ratio of receiving systems with small antennas
Abstract
At low frequencies the bandwidth of the signal-to-noise ratio (S/N) of a receiving antenna with receiver circuit is many orders of magnitude greater than the power bandwidth that may be obtained with an antenna of equivalent height. This S/N bandwidth will be evaluated quantitatively as a function of the antenna temperature, the noise characteristics of a directly connected amplifier network and of the radiator bandwidth. Antenna losses will be taken into account. With single resonant antennas, as for example short folded monopoles, maximum S/N bandwidth is only obtained with a considerable noise mismatch at center frequency. The common line between a passive rod and the matching network in the receiver causes a considerable reduction of the achievable bandwidth. By means of an amplifier being directly connected to a capacitive radiator, short and extremely broadband active receiving antennas, the snr of which is of low-pass character, can be realized.
- Publication:
-
Archiv Elektronik und Uebertragungstechnik
- Pub Date:
- September 1976
- Bibcode:
- 1976ArElU..30..358L
- Keywords:
-
- Antenna Design;
- Bandwidth;
- Monopole Antennas;
- Radio Receivers;
- Signal To Noise Ratios;
- Bipolar Transistors;
- Impedance Matching;
- Low Frequencies;
- Noise Temperature;
- Optimization;
- Rc Circuits;
- Transistor Amplifiers;
- Communications and Radar