Disclosed is a microwave spacer for guiding and positioning microwave energy delivery devices during a surgical procedure. The microwave energy device spacer includes a body forming a plurality of device apertures defined therein, the plurality of device apertures including at least two lumens and at least one arcuate slot. The lumens are configured to receive an energy delivery device therethrough. The arcuate slot includes a length, a width and a radius of curvature and is configured to receive an additional energy delivery device therethrough.