Communications Satellite Corp. (Comsat) announced yesterday that it had agreed in principle to sell a portion of its Texas-based computer-aided engineering software subsidiary to General Electric Co. for $14 million in cash.

Comsat said it would keep the microwave division of the CGIS subsidiary, which is located in Palo Alto, Calif. That division specializes in microwave circuit design tools.

GE's acquisition of the "digital electronics" portion of Comsat's CGIS will be "a perfect fit for Calma," said a GE spokesman. Calma, acquired by GE in 1981, is the company's computer-aided design and engineering subsidiary. According to a company spokesman, it has been growing at an annual 40 percent rate since the acquisition.

"We see it as a big cornerstone for our factory automation business," said Jack Batty, the GE spokesman. GE expects automated factories to be the future of mass production and is expected to invest hundreds of millions of dollars in computer-aided design and manufacturing facilities over the next few years.

Computer-aided design and engineering allow the designer or engineer to model or simulate the effectiveness of their designs. The market is expected to be a large one but requires a large capital investment. The Comsat subsidiary was known to be losing money.

The CGIS move marks the second major sale by Comsat in two weeks. Earlier, the company sold its stake in Ungermann-Bass, a California-based computer networking company, for $4.8 million. That figure is roughly 10 percent of the company's 1982 net profits, according to a Comsat spokesman.

The two sales, say a Comsat spokesman, are the result of "a strategic planning process that began two years ago" to refocus Comsat's corporate resources. The sales have prompted speculation that other Comsat subsidiaries may be for sale. The spokesman would not comment on that speculation.