scholarly journals Observations of the General Background and Discrete Sources of 18·3 Mc/s Cosmic Noise

1954 ◽  
Vol 7 (1) ◽  
pp. 130 ◽  
Author(s):  
CA Shain ◽  
CS Higgins
Keyword(s):  
Galactic Plane ◽  
Beam Width ◽  
Background Distribution ◽  
Broad Strip ◽  
Cosmic Noise ◽  
Half Power

A survey of a broad strip of the sky, centred on Dec. ?32�, has been made at a frequency of 18�3 Mc/s using an aerial with an overall beam width to half-power of 17�. Previous results concerning the background distribution of brightness have been confirmed and 37 discrete sources have been detected. The distribution of these sources shows some galactic concentration ; it becomes homogeneous if sources within 18� of the galactic plane are excluded.

scholarly journals Observations of Cosmic Noise at 9·15 Mc/s

1954 ◽  
Vol 7 (3) ◽  
pp. 460 ◽  
Author(s):  
CS Higgins ◽  
CA Shain
Keyword(s):  
Beam Width ◽  
Sidereal Time ◽  
Cosmic Noise ◽  
Half Power ◽  
Aerial Temperature

From observations made at a frequency of 9� 15 Mc/s, with an aerial of beam width 29� between half-power points and directed to Dec. -32�, a curve of equivalent aerial temperature, as a function of sidereal time, is derived.

scholarly journals A New 21-cm Line Survey of the LMC

1984 ◽  
Vol 108 ◽  
pp. 395-396
Author(s):  
K. Rohlfs ◽  
J. Kreitschmann ◽  
J. V. Feitzinger
Keyword(s):  
Noise Temperature ◽  
Beam Width ◽  
Main Beam ◽  
Corrugated Waveguide ◽  
Line Survey ◽  
Single Polarization ◽  
Switching Mode ◽  
Half Power ◽  
Channel Separation ◽  
Made In

The measurements were made in Feb. 1982 with the Parkes 64 m telescope using a corrugated waveguide horn with total half-power beam width of 15′, the first sidelobes being 19 dB down, resulting in an aperture efficiency ηA=0.53±0.007, a main beam efficiency of ηmb=0.80±0.005 and a ratio of source flux to antenna temperature of Γ=0.62±0.1 K/Jy (Murray, priv. comm.). A cooled two channel FET frontend used in the frequency switching mode with Δν = 2 MHz resulted in a system noise temperature at zenith of Tsyst = 40 K for one channel and Tsyst = 50 K for the other. Each frontend channel received a single polarization mode, and this radiation was then further analysed in a 2 × 512 channel autocorrelation spectrometer set at a channel separation of 3.906 KHz corresponding to a velocity resolution of V = 0.824 km s−1. Hanning smoothed this resulted in a σT = 0.05 K for the average of both polarization.

A Comparison of Swarm-Based Optimization Algorithms in Linear Antenna Array Synthesis

2021 ◽  
Author(s):  
Ali Durmus ◽  
Rifat KURBAN ◽  
Ercan KARAKOSE
Keyword(s):  
Antenna Array ◽  
Radiation Pattern ◽  
Antenna Arrays ◽  
Heuristic Algorithms ◽  
Beam Width ◽  
Side Lobe ◽  
Side Lobe Level ◽  
Linear Antenna ◽  
Half Power ◽  
Antenna Array Synthesis

Abstract Today, the design of antenna arrays is very important in providing effective and efficient wireless communication. The purpose of antenna array synthesis is to obtain a radiation pattern with low side lobe level (SLL) at a desired half power beam width (HPBW) in far-field. The amplitude and position values ​​of the array elements can be optimized to obtain a radiation pattern with suppressed SLLs. In this paper swarm-based meta-heuristic algorithms such as Particle Swarm Optimization (PSO), Artificial Bee Colony (ABC), Mayfly algorithm (MA) and Jellyfish Search (JS) algorithms are compared to realize optimal design of linear antenna arrays. Extensive experiments are conducted on designing 10, 16, 24 and 32-element linear arrays by determining the amplitude and positions. Experiments are repeated 30 times due to the random nature of swarm-based optimizers and statistical results show that performance of the novel algorithms, MA and JS, are better than well-known methods PSO and ABC.

scholarly journals 41. The spherical component of the galactic radio emission

1957 ◽  
Vol 4 ◽  
pp. 233-237
Author(s):  
J. E. Baldwin
Keyword(s):  
Radio Emission ◽  
Brightness Temperature ◽  
Radio Telescope ◽  
Galactic Plane ◽  
Wave Length ◽  
Spherical Component ◽  
Long Wave ◽  
Half Power ◽  
Right Ascension ◽  
Galactic Radio

As part of the programme of observations with the large Cambridge radio telescope, a survey of the integrated radio emission has been made using one of the four elements of the interferometer. At a wave-length of 3·7 metres this aerial has beam-widths to half-power points of 2° in right ascension and 15° in declination. The use of a long wave-length makes it possible to obtain accurate measurements of the brightness temperature of the sky in regions away from the galactic plane. It is with the radiation from these regions that this paper is primarily concerned.

scholarly journals Triple-Band Dual-Polarized Dipole Antenna for 5G Sub-6 GHz Communications

2021 ◽  
Author(s):  
Lixia Yang ◽  
Hafiz Usman Tahseen ◽  
Syed Shah Irfan Hussain ◽  
Wang Hongjin
Keyword(s):  
Return Loss ◽  
Beam Width ◽  
High Gain ◽  
Dipole Antenna ◽  
Base Station ◽  
Iot Applications ◽  
Measured Impedance ◽  
Dual Polarized ◽  
Half Power ◽  
Triple Band

Abstract A triple-band ±45° dual-polarized dipole antenna is presented in this paper. The proposed antenna covers two bands from n77 and one from n79 5G NR frequency spectrums. The profile antenna exhibits the measured impedance bandwidths 3.6-3.85 GHz, 4.05-4.2 GHz and 4.8- 5.15 GHz with S11, S22 < - 15dB return loss. Antenna is fabricated with four substrates; one radiator, one reflector and two feeding baluns. Antenna is designed and optimized with HFSS simulator and fabricated for experimental verification. Antenna gives a stable radiation pattern with 8.55dBi high gain and 70° half power beam width (HPBW) that makes it a good candidate for wireless 5G sub-6 GHz and multiband base station applications. Finally, antenna is tested in a realistic application environment to show the utility of the proposed antenna for wireless sub-6 GHz IoT applications.

scholarly journals Design and Development of Circular Polarized Conformal Microstrip patch Antenna

2019 ◽  
Vol 9 (2S3) ◽  
pp. 106-109
Keyword(s):  
Parametric Study ◽  
Patch Antenna ◽  
Beam Width ◽  
Conformal Structure ◽  
Microstrip Patch Antenna ◽  
Design And Development ◽  
Conformal Antenna ◽  
Microstrip Patch ◽  
Half Power ◽  
Microstrip Feed

This paper presents broadband circular polarized conformal antenna with a square patch for on-board applications. The substrate is located in between patch and the ground. A novel Circular polarized square patch with microstrip feed with two truncated corners with conformal structure is designed. Using a parametric study on the effect of the position of feed, the antenna parameters VSWR bandwidth, half power beam width and polarization of antenna are analysed. Finally fabrication of conformal square patch on 2.2 dialectic substrate and measured results are discussed.

scholarly journals Observations of high velocity HI clouds in the Local Group

1978 ◽  
Vol 79 ◽  
pp. 49-49
Author(s):  
W.K. Huchtmeier
Keyword(s):  
Radio Telescope ◽  
High Velocity ◽  
Local Group ◽  
Neutral Hydrogen ◽  
Beam Width ◽  
Late Type ◽  
M 31 ◽  
High Velocity Clouds ◽  
Half Power ◽  
Magellanic Stream

High velocity clouds (HVC) of neutral hydrogen in or around our galaxy and the observations of intergalactic HI in the Local group: Magellanic stream (Mathewson et al., 1974, Astrophys. J. 190, p. 291), M 31 (Davies, R.D., 1975, Mon. Not. R. astr. Soc., 170, p. 45P), and in the Sculptor group of galaxies (Mathewson et al., 1975, Astrophys. J. 195, p. L97) motivated us to search for HVC-phenomena in a number of nearby late-type galaxies with the 100 m Effelsberg radio telescope which has a half power beam width of 8.5′ at the wavelength of 21 cm.

scholarly journals 4. Progress report on 21-cm. research by the Netherlands Foundation for Radio Astronomy and the Leiden Observatory

1957 ◽  
Vol 4 ◽  
pp. 22-28 ◽  
Author(s):  
G. Westerhout
Keyword(s):  
Noise Figure ◽  
Beam Width ◽  
Local Oscillator ◽  
Line Profiles ◽  
Switching System ◽  
Local Oscillators ◽  
Switching Type ◽  
Frequency Calibration ◽  
Continuous Frequency ◽  
Half Power

From November 1953 to August 1955, about 2500 line profiles have been measured with the Kootwijk receiver, under the supervision of Ir C. A. Muller. His receiver is of the well-known frequency-switching type. Two pairs of channels in the second i.f. amplifier, about 5 Mc./s., have band-widths of 36 kc./s. The components of one pair are 1080 kc./s. apart; the second pair is shifted 500 kc./s. with respect to the first. Each pair of channels, combined with the continuously variable second local oscillator and with the fixed, crystal-controlled pair of first local oscillators, which are also 1080 kc./s. apart, gives a switching system. The power at a certain frequency is compared with that at a 1080 kc./s. higher frequency during half the switching period and with that at a 1080 kc./s. lower frequency during the other half by switching between the two first local oscillators. The signals are fed through an integrating network with a time constant of 54 sec. At the outputs of the two pairs are two separate recorders, each giving one-half (or more) of a line profile (see Fig. 1). A continuous frequency calibration of the second local oscillator provides 10 kc./s. markers on the records, accurate to 1 in 106. The limiting sensitivity is 0·7°K., with an overall noise figure of 6·3 (8·0 db.). The 7·5 m. Würzburg aerial has a beam-width between half-power points of 1°·9 × 2°·7.

scholarly journals Fundamental Limits on Detection of UAVs by Existing Terrestrial RF Networks

2021 ◽  
Author(s):  
Priyanka Sinha ◽  
Ismail Guvenc ◽  
Mustafa Cenk Gursoy
Keyword(s):  
Beam Width ◽  
Analytical Framework ◽  
Line Of Sight ◽  
Fundamental Limits ◽  
3D Network ◽  
Optimal Beam ◽  
Sensor Density ◽  
Half Power ◽  
The Impact ◽  
Spatial Randomness

Detection of drones carries critical importance for safely and effectively managing unmanned aerial system traffic in the future. Given the ubiquitous presence of the drones across all kinds of environments in the near future, wide area drone detection and surveillance capability are highly desirable, which require careful planning and design of drone sensing networks. In this paper, we seek to meet this need by using the existing terrestrial radio frequency (RF) networks for passive sensing of drones. To this end we develop an analytical framework that provides the fundamental limits on the network-wide drone detection probability. In particular, we characterize the joint impact of the salient features of the terrestrial RF networks, such as the spatial randomness of the node locations, the directional 3D antenna patterns, and the mixed line of sight/non line of sight (LoS/NLoS) propagation characteristics of the air-to-ground (A2G) channels. Since the strength of the drone signal and the aggregate interference in a sensing network are fundamentally limited by the 3D network geometry and the inherent spatial randomness, we use tools from stochastic geometry to derive the closed-form expressions for the probabilities of detection, false alarm and coverage. This, in turn, demonstrates the impact of the sensor density, beam tilt angle, half power beam width (HPBW) and different degrees of LoS dominance, on the projected detec?tion performance. Our analysis reveals optimal beam tilt angles, and sensor density that maximize the network-wide detection of the drones.

scholarly journals A Cross-Joint Vivaldi Antenna Pair for Dual-Pol and Broadband Testing Capabilities

2021 ◽  
Vol 21 (3) ◽  
pp. 201-209
Author(s):  
Gwang-Hun Jeon ◽  
Philip Ayiku Dzagbletey ◽  
Jae-Young Chung
Keyword(s):  
Wireless Communication ◽  
Low Cost ◽  
Impedance Matching ◽  
Beam Width ◽  
Communication Devices ◽  
Operating Bandwidth ◽  
Vivaldi Antenna ◽  
Increasing Demand ◽  
Half Power ◽  
Vivaldi Antennas

The non-standalone 5G antenna wireless communication standard and devices operating under Wi-Fi 5, 6, and 6E operate at the 3 GHz frequency bands and above. With the increasing demand for these devices and technologies, it is crucial to test them rapidly and economically for commercial usage. This paper presents a dual-polarized Vivaldi antenna for the over-the-air (OTA) measurement of wireless communication devices used in the 3–7 GHz band. The dual-polarization performance is realized by vertically intersecting two planar Vivaldi antennas and soldering them at the back end. A three-step 1/4 wavelength balun is applied to the input for the wideband impedance matching of the antenna, which is attached to a Teflon holder for easy mounting. It has excellent performance and is designed to be manufactured at low cost. The fabricated antenna was tested in an anechoic chamber and showed S11 less than -10 dB from 2.63–7.15 GH, and a realized gain of more than 5 dBi from 3 GHz and above. A measured half-power beam width of more than 60° was realized with symmetric E/H-plane. Much of the required symmetry was achieved with the designed Teflon holder. The antenna has a measured cross-polarization discrimination of better than 15 dB across the entire operating bandwidth.

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