Optimizing the base material and electrode structure of photoconductive antennas is crucial for enhancing their terahertz wave radiation performance. Compared with traditional photoconductive antennas （PCAs）， the interdigital photoconductive antenna （IPCA） can accommodate multiple array elements within a smaller photosensitive area， leading to better radiation performance. This study designed and developed six types of IPCAs with varying numbers of array elements and electrode gaps. By introducing metal layer shielding to eliminate the reverse electric field between adjacent electrodes， the radiation and polarization characteristics of the IPCA were compared with those of traditional PCAs （parallel electrode and bowtie antennas）. Furthermore， variations in the radiation characteristics of the IPCA with respect to the number of array elements， electrode gaps， pump light energy， and bias electric field were investigated. Experimental results show that the THz pulse radiation amplitude of a 40-array-element IPCA is 30 times higher than that of a single antenna.