This talk will present an overview of the activities in the microwave group at the University of Colorado, Boulder, followed by a more detailed discussion of a few specific projects: (1) high-efficiency microwave transmitters for non-constant envelope communication and radar signals, from 3kW to 5W in power level, and 450MHz to 10GHz in frequency; (2) micro-fabricated G-band frequency-steered antenna arrays for planetary landing radar operating in the 130 to 180GHz frequency range; (3) microwave radiometers for internal body thermometry, and time permitting, (4) far-field wireless powering for low-power wireless sensors. Related to the first topic, for example, several transmitters will be presented, for applications such as wind-profiling radar with 3-kW LDMOS pulsed 449-MHz PAs with efficiencies greater than 65%, to S-band hybrid GaN PAs with 10W output power and PAE>80% and X-band 10-W MMIC GaN PAs with PAE>60%. These amplifiers are integrated into transmitters that use different architectures to maintain efficiency for varying amplitude signals, such as supply modulation, outphasing and harmonic injection.