Linear amplifier combiner

Present performance of cellular systems is restricted by the method used to combine signals before they are transmitted from the cell site. This combining is accomplished using resonant filters which are mechanically tuned. Changing frequency assignments is not easily done. A significant improvement in cellular system performance can be achieved by using a linear amplifier in combination with a broad band passive combiner. In the present system, each individual signal has its' own separate power amplifier. The outputs from these are combined at high power by using frequency isolation to reduce losses. With the linear amplifier, the combining is done at low power where the losses can be tolerated. The combined signals are then amplified by a single linear amplifier to bring them to the transmit power level. The linear amplifier combiner arrangement essentially eliminates the rigid frequency restrictions which now exist. Channel assignments can be changed as required without mechanical tuning. The channel spacing limitation required by the existing combiners is also eliminated. The number of signals which can be transmitted from one antenna is now limited only by total power consideration. The linear amplifier also permits modulation schemes which make more efficient use of the available spectrum.