A Hard Copper Open X-Band RF Accelerating Structure Made by Two Halves

This communication focuses on the technological developments aiming to show the viability of novel welding techniques [...]

DESIGN AND ANALYSIS OF A MICROSTRIP PATCH ANTENNA AT 7.5 GHz FOR X-BAND VSAT APPLICATION

In this paper, a microstrip patch antenna is designed to be used for X-band VSAT application at 7.5 GHz. The antenna is proposed to replace the massive and commonly used parabolic reflector antennas (46.0 inch × 29.3 inch × 13.5 inch (116.84 cm × 74.42 cm × 34.29 cm) with weight of 66.2 kg) in terms of portability due to its compact and lightweight features, with overall dimensions of 19.00 mm × 30.55 mm. The 7.5 GHz frequency is chosen based on the X-band frequency used in Malaysia, as reported by STRIDE. The microstrip patch antenna is first designed and simulated using CST Microwave Studio (CST MWS) and exhibits a good return loss (S11) of -42.09 dB, a bandwidth of 399 MHz, directivity of 7.63 dB and gain of 7.18 dB. The antenna is then fabricated using RT/duroid ® High Frequency 5880 substrate with a dielectric constant of ?r = 2.2, loss tangent of ? = 0.0009 and thickness of t = 1.574 mm. Next, the return loss and radiation pattern measurements are carried out to confirm the simulated results. The measurement of the antenna prototype provides a return loss S11 of -30.53 dB, bandwidth of 455 MHz, directivity of 5.51 dB and gain of 3.88 dB. ABSTRAK: Di dalam kajian ini, antena jalurmikro dicadangkan untuk tujuan aplikasi jalur-X VSAT pada 7.5 GHz. Antena jalurmikro ini dicadangkan untuk menggantikan antena reflektor parabola yang besar dan biasa digunakan (46.0 inci × 29.3 inci × 13.5 inci (116.84cm × 74.42cm × 34.29cm) dengan berat 66.2kg), kerana cirinya yang mudah alih dengan fizikalnya yang kecil dan ringan, dan dimensi keseluruhan 19.00 mm × 30.55 mm. Frekuensi 7.5 GHz dipilih berdasarkan frekuensi jalur-X yang digunakan di Malaysia, seperti yang dilaporkan oleh STRIDE. Antena jalurmikro ini direka dan disimulasi menggunakan perisian CST Studio Gelombang Mikro (CST MWS) dan menghasilkan kehilangan pulangan yang baik S11 -42.09 dB, lebar jalur 399 MHz, keterarahan 7.63 dB dan gandaan 7.18 dB. Antena jalurmikro ini kemudiannya direalisasikan dengan menggunakan substrat RT / duroid ® Frekuensi Tinggi 5880 dengan pemalar dielektrik ?r = 2.2, tangen kehilangan ? = 0.0009 dan ketebalan t = 1.574 mm. Seterusnya, pengukuran kehilangan pulangan dan corak radiasi dilakukan untuk mengesahkan keputusan simulasi. Pengukuran prototaip antena jalurmikro menunjukkan kehilangan pulangan S11 -30.53 dB, lebar jalur 455 MHz, keterarahan 5.51 dB dan gandaan 3.88 dB.

The New Wuqing 70 m Radio Telescope and Measurements of Main Electronic Properties in X-band

The new Wuqing 70 m radio telescope is firstly used for the downlink data reception in the first Mars exploration mission of China, and will be used for the other deep space communications and radio astronomical observations in the future. The main specifications and measurement results of some properties in X-band are introduced in this paper, such as pointing calibration, gain and efficiency, system noise temperature, system equivalent flux density, and variations with elevation. The 23 parameters pointing calibration model considering the atmospheric refraction correction in real time is presented in the telescope, and the pointing accuracy is reached 5.70″ in azimuth direction and 6.07″ in elevation direction respectively for different weather condi-tions. More than 62% efficiencies are achieved at full elevation range, and more than 70% in the mid-elevation. The system equivalent flux density of X-band in the mid-elevation is reached 26 Jy.