Interdigitated photomixing antennas (PMA), are amongst the most common sources for future terahertz wireless communication systems. In this contribution, a novel and interesting design of a PMA employing graphene as its electrode material has been proposed. The use of graphene provides several potential advantages over conventional metallic electrodes. Variation of the PMA output as a function of various parameters have been discussed and a novel scheme for producing modulation in the PMA output, using an additional signal source, has been introduced. The multiphysical scenario in the functioning of the PMA has been elegantly analyzed with a generalized and simple model. Expressions for the radiated fields from the antenna have been derived using the proposed model and have been validated with full-wave simulations. This paper introduces a procedure for simulating the antenna on commercial EM solvers. Several strategies to modulate the output of antennae, which is crucial for them to be suitable for wireless communications, have also been proposed and discussed with several key findings. The role of some of the antenna parameters have also been investigated. The uniqueness of this analysis lies in its simplicity and generalization along with its capability to combine the multi-physical scenario in the operation of the PMA. © 2018 IOP Publishing Ltd.