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After years of preparation, the Indonesia National Observatory, located in Mount Timau, Kupang Regency, is currently in the completion stage of research in astronomy and astrophysics and related subjects. An optic telescope with a 3.8 m diameter is expected to receive its first light in mid-2024. A feasibility study for Indonesia's radio telescopes and networks is in progress. A single-dish parabolic radio antenna with a diameter of 20 m is proposed to work in a frequency range of 1–50 GHz. An array dipole antenna with an area of 100 m × 100 m will also be installed at a 70–350 MHz frequency. A feasibility study about system design is in progress, and a radio frequency interference (RFI) survey has been underway since 2014. In this paper, we described the design of radio telescopes such as parabolic reflectors, horn antenna, and the radio frequency interference (RFI) in the surrounding area of the National Observatory, covering the frequency band from 45 MHz to 18 GHz. The frequencies in 45–85 MHz and 120–360 MHz intervals are still relatively quiet and suitable for developing radio telescopes. The selected higher frequency of 1.4 GHz for a neutral hydrogen (HI) spectral line, 6.6 GHz for a methanol (CH3OH) spectral line, and 8.6 GHz for a helium (3 He+) spectral line is still relatively quiet and suitable for the development of radio telescopes. [ABSTRACT FROM AUTHOR]

Dielectric resonator oscillators (DRO) have been recognized as the basic energy source in microwave telecommunication, radar, and navigation systems. This paper reports fabrication and characterization of structure, microstructure and dielectric properties of (Mg0.8Zn0.2)(Ti0.99Sn0.01)3 ceramics (MZTS hereafter) as a DR, a well as characterization of key parameters of a DRO module, i.e. resonant frequency, output power, bandwidth and phase noise, when the ceramics were used as a resonator in the module. Five-mm diameter solid cylindrical MZTS ceramics were fabricated and sintered at 1100 °C for 4, 6, 8, and 10 h. XRD, SEM–EDS and Network Analyzer were used to characterize the structure, surface morphology, εr and Q factor at 3.3 GHz, and τf of the ceramics. The εr of 17.34–17.48, Q factor of 6464–6510 at 3.3 GHz, and τf of 38–59 ppm/°C measured over 25–70 °C. The DRO key parameters were measured using a Spectrum Analyzer at a transverse electric (TE)01δ resonant mode with 12 Volt dc biasing. The ceramics recorded the resonant frequency at 4.0 GHz which are stable for 1 h with large output power, narrow bandwidth, and low phase noise at 300, 500, 700 kHz, and 3 MHz offset frequencies. The best DRO characteristics was shown by the 8 h ceramic, i.e. the resonant frequency at 4.05 GHz with -6.55 dBm output power, 58.50 kHz bandwidth, and -114.56 dBc/Hz phase noise at 700 kHz offset frequency. With such performance, MZTS ceramics are promising to be used as a silent oscillator in C-band radar systems. [ABSTRACT FROM AUTHOR]

CoNdxFe(2−x)O4 (x = 0.0–0.05) spinel ferrites are successfully synthesized by mechanical milling using solid‐state reaction. The effects of Nd3+ ions on structural, microstructure, and magnetic and microwave‐absorbing properties of samples are analyzed. The X‐ray diffraction pattern shows a single‐phase cobalt ferrite for all compositions. Refinement of the structure shows that an increase in the concentration of Nd3+ ions leads to the structure parameter and volume of unit cell to decrease. Lattice strain arises in the crystal, and limiting the crystallite growth is confirmed from the Williamson–Hall analysis. The particle size of the doping samples decreases compared to that without doping. The magnetic parameters, namely coercivity field and saturation magnetization, are strongly affected by the insertion of Nd3+ ions. Another important role of Nd3+ ions is in tuning the performance of microwave absorption. The maximum reflection loss values are gradually increased from −12.65 dB (≈94.35% microwave attenuation) up to −28.57 dB (≈99.86% microwave attenuation) in the concentration of x = 0.0–0.05. Their effective bandwidth also shows an increase from 0.05 up to 1 GHz. The results exhibit that Nd3+ ion‐doped cobalt ferrite has potential properties in designing novel microwave‐absorbing materials. [ABSTRACT FROM AUTHOR]

The design of 2-stage low noise amplifier (LNA) working at S-band frequency is proposed by using non simultaneous-conjugate-match technique. Implementation of the technique is motivated by the circumstance that the gain of LNA designed by the familiar technique, i.e. simultaneous-conjugate-match is almost followed by arise of values in noise figure (NF) and voltage standing wave ratio (VSWR). In the design process, the ADS software is applied to determine the desired trade-off value between LNA parameters such as gain and VSWR. The 2-stage LNA which is deployed on an Arlon DiClad527 applies BJT transistors of BFP420. To achieve the impedance matching condition, microstrip lines are employed at the input and output ports. From the experimental characterization, it shows that the prototype of 2-stage LNA produces the gain of 24.32 dB at 3GHz which is 4.56 dB lower than the simulated result. [ABSTRACT FROM AUTHOR]