In this paper, a dual-band shared-aperture reflectarray (RA) with a phased array is proposed for inter-satellite links. The Ka-band reflectarray is integrated with an X-band phased array by a sharing mushroom patch structure. The high-frequency ratio allows the high-frequency reflectarray and the low-frequency broadband phased array to operate independently to support high-speed communication of the geostationary orbit (GEO) relay nodes in the inter-satellite network. To verify this concept, a prototype of the antenna is designed and fabricated, and its electrical performance is measured. The reflectarray presents a peak gain of 30.1 dBi (28 GHz) and a 3 dB gain bandwidth of 11.4% (26.4 to 29.6 GHz). The phased array presents the peak gain of 21.7dBi (9 GHz), and the relative bandwidth can reach 45.3% in the boresight direction. The scanning range can cover ± 45°, and the H/E planes scan gain losses are less than 2.34 dB and 4.33 dB, respectively.

A new efficient synthesis method of angular selective surfaces (ASSs) based on the accurate equivalent circuit model is proposed. The angular dispersion of different components under oblique incidence is modeled by virtual lumped elements in the angular domain. The processes of obtaining the equivalent circuit for substrates, electrically small grids and patch arrays are presented in detail. The synthesized circuits are simple and accurate. Full-wave simulations are carried out to obtain the angular dispersion of different structures, and the calculated results are in good agreement with those of the equivalent circuit. A third-order ASS with bandpass response and a second-order ASS with a tunable bandwidth are given as design examples. The implemented second-order ASS shows the 0.33 to 0.52 tunable bandwidth in the angular domain. The transmission loss is better than 1.2 dB when the incidence angle is 65 $^\circ$ –77 $^\circ$ . The simulation results and calculated results are in good agreement with the measured results.

This article proposes a dual-band, frequency- and polarization-selective surface. Multiple resonant modes are introduced using the U-shaped resonator with a ground via to achieve dual-band responses and polarization selectivity. Two symmetrically grounded U-shaped resonators are coupled through electrically coupled apertures in a common ground, resulting in a passband with two transmission zeros per polarization. A general design flowchart and additional examples at the S, X, and K-bands are presented as well. A prototype at X-band is analyzed, fabricated, and measured, showing the passband center frequencies of 9.68 GHz and 10.73 GHz, factional bandwidths of 3.45% and 3.48%, and insertion losses of 0.9 dB and 1.1 dB, respectively. Due to the high selectivity, small frequency ratio, low profile, and stable performance under oblique incidence, the proposed designs have application potential in wireless communication systems.

This article presents two miniaturized multimode waveguide bandpass filters (BPFs) based on epsilon-near-zero (ENZ) channel concept. By connecting parallel shorting stubs on the ENZ channel, multiresonance modes and one transmission zero (TZ) are introduced, broadening the bandwidth of the passband and upper stopband, respectively. The effect of arbitrary waveguide discontinuity on this resonant mechanism is analyzed, and the effective size reduction of the third-order filter is achieved with the folded ENZ channel. The design procedure and miniaturization of the proposed BPFs are presented in detail. The proposed second-order filter shows a 6.8% 3-dB fractional bandwidth (FBW) with a center frequency of 9.6 GHz, an insertion loss of 0.42 dB at 9.6 GHz, and an out-of-band rejection of 30 dB up to 12 GHz. Especially, with the filter thickness of 2.3 mm ( 0.245 λ _g at 32 GHz), the fabricated third-order filter shows a 6.2% 3-dB FBW with a center frequency of 32 GHz, an insertion loss of 0.6 dB at 32 GHz, and an out-of-band rejection of 30 dB up to 36 GHz. Simulated and experimental results are of good agreement.

Future communications will provide higher transmission rates and higher operating frequencies. In addition, agile beam tracking will be an inevitable trend

This paper presents a high-isolation, low crosspolarization, differential-feed, dual-polarized microstrip patch antenna array. By using differential feeding and coupled structure, the array realizes high port isolation, which is suited for the full duplex operating mode with two orthogonal linear polarizations of transmitting and receiving, respectively. Simulations results show isolation is greater than 40 dB at 2–5.2 GHz and greater than 60 dB at 2.42–2.47 GHz. The crosspolarization level is less than –40 dB on both the E and H planes. The proposed array has a simple structure to fabricate and practical for use in the retrodirective system.