Abstract An innovative inverted ground eight-branch planar spoof surface plasmon polaritons (SSPP) leaky-wave (LW) satellite receive array antenna at the Ku frequency band with linear polarization, boresight radiation, high gain, and low frequency scanning angle is proposed. A novel one port approach using an open-ended SSPP standing wave (SW) waveguide, is used. An innovative inverted ground is used to increase the antenna performance, which to the best of our knowledge have not been introduced for SSPP antennas before. The efficacy of the inverted ground design is validated by comparing its performance characteristics with those achieved by traditional ground by simulation and measurement. A prototype antenna is fabricated with impedance bandwidth, the peak antenna gain, and frequency scanning of 0.98 GHz, 30.2 dBi and 3.6°, respectively. The proposed antenna can provide the high gain and low frequency scanning required for 5G, 6G, geostationary orbit (GSO) and emerging non-geostationary orbit (NGSO) satellite applications.
This paper proposes a balanced filter design method based on multi-mode ring resonators. By optimizing the resonator structure, independent control of center frequencies of the dual passbands is achieved. Additionally, parallel-coupled feeding is adopted, and the external quality factor is adjusted by tuning the spacing between the feed lines and resonators, enabling independent optimization of the bandwidth for both passbands. Experimental results show that the filter achieves a return loss of less than -17 dB within the dual passbands, an inter-passband isolation exceeding -40 dB. The minimum common-mode mode (CM) suppression of the differential mode (DM) passbands are 41.9 dB and 42.2 dB. The fabricated and tested filter demonstrates good agreement between simulation and measurement results.
In the paper, a dual-band microstrip bandpass filter (BPF) featuring high selectivity and quasi-independently reconfigurable frequencies is proposed. The proposed BPF is realized using two sets of asymmetric quarter-wavelength short stub-loaded resonators. The source-load coupling is achieved by adopting a parallel-coupled three-line structure, which can generate multiple transmission zeros (TZs) and enhance the selectivity of each passband greatly. By adjusting the electrical length ratio of the resonators, the center frequencies of the two passbands can be controlled quasi-independently. Ultimately, four varactor diodes of SMV1430 are employed to realize the dual-band reconfigurability. The tuning ranges of the two passbands of the proposed BPF are 430 MHz and 900 MHz, respectively, with insertion loss consistently below 5 dB across the entire tuning range. To validate the design methodology, a prototype of the filter was fabricated and tested, demonstrating good correlation between measured and simulated results.
In the THz spectrum, Graphene exhibits immense potential for the development of ultra-compact antennas due to its distinctive tunability feature. This paper presents a flexible wearable THz antenna using graphene nanomaterial for wireless body area network (WBAN) applications. The proposed antenna consists of a rectangular graphene patch placed over the polyamide substrate. The antenna design is optimized at 3 THz for on-body wearable applications. The body and bending effects of the proposed antenna are analyzed in this work. Specifically, the body effects, including the skin, fat, and muscle, with air gaps of different values, are investigated. The results show that the proposed graphene THz antenna holds great promise for WBAN applications.
This article presents the scheme of a tunable absorptive bandpass filter with an ultra-wide reflectionless range, which is composed of a tunable reflective BPF and a tunable reflective bandstop filter. A lowpass prototype for the absorptive bandpass filter with reflectionless characteristics at all frequencies is proposed, which is transformed into a bandpass circuit model using impedance converters while maintaining the reflectionless characteristics over the whole frequencies. In addition, parallel coupled lines are chosen to realize the absorptive filter, and varactor diodes are introduced to achieve the tunable characteristics. The proposed filter has been fabricated and the measurements show a tuning range of 38.7 % (from 1.02 GHz to 1.51 GHz) and a reflectionless range of over 20:1 (from 0.1 GHz to 2 GHz).
