In one of the student design competitions at the IEEE MTT-S International Microwave Symposium 2011 (IMS2011) held at Baltimore, Maryland, the objective of the competition is to demonstrate the effective triplexer design techniques with the constraints of the metal package. The additional specifications are described as follows: insertion loss between CP and any in-band port less than 3.5 dB, insertion loss between CP and any port at frequencies 15% or more separated from the port's center frequency more than 20 dB, return loss for each in-band port better than 15 dB, return loss for CP at 3.35 GHz more than 15 dB, and isolation between output ports 2, 3, and 4 more than 20 dB. According to the requirements of the contest, two pieces of hardware are fabricated and measured. One is the unpackaged triplexer designed on printed circuit board (PCB) to validate the feasibility of design concepts. The packaged one has to maintain the first design's topology, but component values can be adjusted to compensate return loss and isolation after taking the package's effect into consideration. Both circuits must be connected with 50- female subminiature version A (SMA) connectors, which are defined as reference planes while the triplexers are being measured.