High-Gain Dielectric Lens Antenna Fed by Circular Dielectric Waveguide for Applications in D-Band

This paper illustrates the design of a high-gain dielectric lens antenna that is fed by a circular dielectric waveguide (CDWG) in the frequency range of 115–130 GHz. A 1.75 mm diameter CDWG made up of low density polyethylene (LDPE) is used to feed the lens antenna. The fundamental mode of the CDWG is excited with the help of a transition from the rectangular waveguide WR6.5. The paper analyses the different parameters of the lens antenna and their effects on the gain and matching. Two lenses made up of different materials, High Density Polyethylene (HDPE) and Polytetrafluorethylen (PTFE), are fabricated and measured. A holding structure is also made to hold the lens in place and in contact with the CDWG. Another antenna is made where this holder is removed and the CDWG is inserted inside the lens antenna by drilling a hole in the center of the lens. This also makes the setup very compact. The matching is measured with a calibrated VNA and all antennas have a return loss greater than 17 dB throughout the design range (better than 22 dB up to 126 GHz). The gain measurements are taken using a three-antenna gain method with the help of two D-band pyramidal horn antennas. A measured gain between 20.5 and 22.5 dBi is found for all the lens antennas. A good accordance to simulation is found. These lens antennas could be easily integrated to advanced system applications in D-band.