A monolithic geodesic H-plane horn array antenna that operates up to 170 GHz is achieved for the first time using a low-cost additive manufacturing (AM) technique. To reach high gain and symmetric beam, a truncated geodesic H-plane horn is used to obtain a narrow beam in the H-plane, while a 1 : 8 power divider built on parallel-plate waveguides is constructed to narrow the beam in the E-plane. A ray-tracing and physical-optics model is developed to facilitate the design, which is capable of computing the full radiation pattern, directivity, and gain (considering conductive losses) of geodesic H-plane horn array antennas with significant time efficiency and high degree of accuracy. The adopted metal-only laser powder-bed fusion AM technique is especially suitable for fast prototyping structures with intricate shapes at a low cost. However, special adaptations are still considered in the design to ensure a successful fabrication of the prototype operating at the D-band. The prototype maintains good frequency stability from 110 to 170 GHz with a return loss better than 10 dB and a symmetric pencil beam. The measured data show a maximum realized gain of 29 dBi, a maximum aperture efficiency of 67% (calculated using realized gain), and a maximum radiation efficiency of 86%.

The spurious transmission dips that occur in glide-symmetric holey gap waveguides (GSHGWs) are systematically characterized in this work, and the obtained information is used to suppress them in the intended operating band of the gap waveguide. The analysis relies on the dispersion characteristics of the waveguide segment with electromagnetic bandgap (EBG) holes. These characteristics are explored through the multimodal transfer matrix approach, particularly focusing on identifying relevant edge and waveguide modes. We find four types of unwanted dips in the transmission coefficient within the intended operation frequency band of the gap waveguide under study. The first three types are all associated with the edge mode mostly concentrated in the small air-gap region between the waveguide and the EBG holes, whereas the fourth type is caused by a narrow stopband in the waveguide mode. Based on a thorough understanding of all dips, we propose three viable solutions: placing EBG holes away from the waveguide channel, intersecting EBG holes with the waveguide channel, and intersecting additional small holes with the waveguide channel and the EBG holes. After comparison, the last solution with two small holes per EBG hole along the waveguide channel was demonstrated to be the most advantageous in terms of transmission properties, compactness, and flexibility. This solution was also experimentally validated using a WR-19 GSHGW operating from 35 to 63 GHz.

In this paper, we present a hybrid electromagnetic bandgap (EBG) structure based on a three-hole double-layer configuration. One layer of the EBG structure is positioned on the metal, while the other is on the printed circuit board (PCB). Dispersion analyses reveal that this new compact hybrid EBG could produce a wide stopband with high in-band attenuation. To evaluate its effectiveness in mitigating signal leakage at waveguide-to-PCB interfaces and its potential application in next-generation satellite communications (Sat-Corns), we designed two EBG structures specifically for low-Earth orbit and geosynchronous orbit SatCom hybrid array antennas within the E-band (71-86 GHz). The performance of these EBG structures is evaluated in the configuration of 4 × 4 hybrid arrays. We demonstrate that the proposed hybrid EBG structures can effectively enhance power transmission and significantly reduce mutual coupling in the waveguide-to-PCB interfaces.

We present a low-loss shared-aperture dual circularly polarized 4x4 lens array antenna for full-duplex geostationary satellite communications in the K/K-a-band. The proposed array has a periodicity of approximately 2 lambda in the K-a-band and 1.5 lambda in the K-band, with the resulting grating lobes suppressed by highly directive array element patterns. Two separate sequential rotation feed networks (for the K and K-a-bands) are implemented using a combination of H-plane ridged waveguides and E-plane rectangular waveguides. The feed works for the two bands are stacked. The performance of the proposed lens array is validated using full-wave simulations in CST. In the receiving band of 17.7 - 20.2 GHz, the array achieves a right-hand circular polarization with an axial ratio lower than 2 dB, a realized gain of 23 dBic, a total antenna efficiency of more than 85%, and a return loss higher than 10 dB. In the transmitting band of 27.5 - 30 GHz, the array achieves a left-hand circular polarization with an axial ratio lower than 1.5 dB, a realized gain of 27 dBic, a total antenna efficiency of more than 80%, and a return loss higher than 10 dB.

Glide-symmetric holey electromagnetic bandgap (EBG) structures have found wide applications in high-frequency gap waveguide components because of their demonstrated wide stopband and easy manufacturing. However, potential dips in the transmission through the gap waveguide at certain frequencies limit the effective bandwidth. Here, we perform a Bloch analysis of the unit cell, a rectangular waveguide segment implemented with the glide-symmetric holey EBG, using a multimodal transfer matrix method. We find two main spurious dips in the transmission coefficient in the recommended operating frequency band of the investigated WR-15 standard rectangular waveguide. The first transmission dip is found to correspond to the coupling of the waveguide mode and the edge mode formed in the air gap between the waveguide and the EBG holes. The second transmission dip is caused by a small open stopband in the waveguide mode.

We present a compact geodesic H-plane horn antenna for point-to-point communications at W-band. The horn has a curved height profile with truncated corners to reduce phase errors and achieve high gain and aperture efficiency. The laser powder-bed fusion additive manufacturing technique is applied to fabricate the horn antenna in a monolithic manner. The resulting prototype has a weight of only 14 g including the flange part. In the operating band from 75 to 110 GHz, the measured reflection coefficient is below -15 dB in almost the entire band and agrees well with the expectations from the simulation. The simulation shows a realized gain of 20 dBi with an aperture efficiency of 80% and a total efficiency of nearly 80%.

We present a compact geodesic H-plane horn antenna for point-to-point communications at W-band. The horn has a curved height profile with truncated corners to reduce phase errors and achieve high gain and aperture efficiency. The laser powder-bed fusion additive manufacturing technique is applied to fabricate the horn antenna in a monolithic manner. The resulting prototype has a weight of only 14 g including the flange part. In the operating band from 75 to 110 GHz, the measured reflection coefficient is below -15 dB in almost the entire band and agrees well with the expectations from the simulation. The simulation shows a realized gain of 20 dBi with an aperture efficiency of 80% and a total efficiency of nearly 80%.

A compact and lightweight geodesic H-plane horn antenna is designed and experimentally validated in the W-band. Two corners in the aperture of the horn are truncated to increase aperture efficiency and reduce the weight and volume of the antenna. The prototype was monolithically printed in AlSi10Mg through laser powder-bed fusion additive manufacturing, resulting in a weight of only 14 g. The prototype maintains good frequency stability from 75 to 110 GHz, with sidelobe levels lower than −25 dB and return loss better than 15 dB. The measured data show a realized gain of 20 dBi with an aperture efficiency of around 60% (calculated using realized gain) and an estimated radiation efficiency of better than 70%.

This paper proposes a combined ray-tracing and physical-optics model to analyze parallel-plate-waveguide lens antennas with a flat aperture. A family of rays is traced from the source to a set of target points on the lens radiating aperture, giving a description of the aperture electric field. On the basis of the physical-optics approximation, an equivalent magnetic current is then assumed and used to evaluate the far-field radiation characteristics in every direction. This numerical approach is validated by applying it to a particular planar Mikaelian lens antenna and comparing the results with those obtained using a commercial full-wave simulator.