Cyclotron Radiation Emission Spectroscopy (CRES) is a
technique for measuring the kinetic energy of charged particles
through a precision measurement of the frequency of the cyclotron
radiation generated by the particle's motion in a magnetic
field. The Project 8 collaboration is developing a next-generation
neutrino mass measurement experiment based on CRES. One approach is
to use a phased antenna array, which surrounds a volume of tritium
gas, to detect and measure the cyclotron radiation of the resulting
β-decay electrons. To validate the feasibility of this method,
Project 8 has designed a test stand to benchmark the performance of
an antenna array at reconstructing signals that mimic those of
genuine CRES events. To generate synthetic CRES events, a novel
probe antenna has been developed, which emits radiation with
characteristics similar to the cyclotron radiation produced by
charged particles in magnetic fields. This paper outlines the
design, construction, and characterization of this Synthetic
Cyclotron Antenna (SYNCA). Furthermore, we perform a series of
measurements that use the SYNCA to test the position reconstruction
capabilities of the digital beamforming reconstruction technique. We
find that the SYNCA produces radiation with characteristics closely
matching those expected for cyclotron radiation and reproduces
experimentally the phenomenology of digital beamforming simulations
of true CRES signals.