A Multiple Unit Steerable Antenna for Short-Wave Reception

Friis, H.T.; Feldman, C.B.

doi:10.1109/jrproc.1937.228354

Cited by 61 publications

(10 citation statements)

References 9 publications

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“…The absolute values of the equivalent temperatures are considerably higher than values deduced from the observations of Friis and Feldman (1937). Townes (1947) has shown that the maximum noise intensity observed by Friis and Feldman at 9·5 Mc/s corresponded to an equivalent temperature of only 120,000 oK.…”

Section: Tocj-28mentioning

confidence: 77%

“…Observations in this range of frequencies are rare, the only published work at a frequency close to 10 Mc/s consisting of a few measurements at 9·5 Mc/s by Friis and Feldman (1937) which were made during tests of the original MUSA aerial. A recent paper (Shain and Higgins 1954) presented the results of a detailed survey of a restricted region of the sky at 18·3 Mc/s, but the results of some earlier work at the same frequency (Shain 1951), in which a strip of the sky was scanned by a fixed aerial directed to a constant declination, have already been used by Piddington (1951) and Brown and Hazard (1953) for comparison with their theoretically predicted intensities.…”

Section: Introductionmentioning

confidence: 99%

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Observations of Cosmic Noise at 9·15 Mc/s

Higgins¹,

Shain²

1954

Aust. J. Phys.

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SummaryFrom 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.The temperatures observed were of the order of 10· OK. The curve is compared with curves derived for similar conditions by calculation from the results of observations at 18·3 Mc/s and at 100 Mc/s_ It is found that the equivalent temperatures increase rapidly with decreasing frequency, but the ratio of maximum to minimum temperature decreases with frequency.It is shown that" atmospheric" noise levels observed by the standard techniques sometimes contain a large contribution from cosmic noise at this frequency.

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Section: Tocj-28mentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Observations of Cosmic Noise at 9·15 Mc/s

Higgins¹,

Shain²

1954

Aust. J. Phys.

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“…Phase shifters are a common component in microwave and millimeter‐wave systems for having a controlled relative phase delay between different parts of the system, which is necessary in many applications such as radar, amplifiers, or phased arrays. The use of phased arrays in wireless systems allows to produce radiation patterns that point in a certain specified direction. When the phase of the signal that illuminates each radiating element of the array can be modified, it is possible to change the pointing direction of the array without the need of physically moving it.…”

Section: Introductionmentioning

confidence: 99%

Reconfigurable H‐plane waveguide phase shifters prototyping with additive manufacturing at K‐band

Polo‐López

Masa‐Campos

Ruiz‐Cruz

2019

Int J RF Microw Comput Aided Eng

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This work presents the design and manufacturing of a K‐band reconfigurable phase shifter completely implemented in waveguide technology for reduced insertion loss, good matching, and large phase shifting range. The device is based on the combination of a short slot coupler and two tunable reactive loads implemented as a section of short‐circuited waveguide where an adjustable metallic post is inserted. Three prototypes of this design have been manufactured using different techniques (conventional computer numerical control machining, a low‐cost fused filament fabrication technique and direct metal laser sintering) in order to assess its performance for different applications. The prototypes have been characterized experimentally and the achieved results are evaluated and compared. The proposed phase shifter, since it is fully developed in waveguide technology, eliminates the need of adding transitions to planar structures in order to integrate lumped components like pin diodes or varactors. Therefore, this device has a great potential in high‐power beam steering phased arrays.

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“…This was already investigated in 1937 [5] and forms the basis for the success of modern OFDM modems intended for HF use. Fading reduction using adaptive beam forming, by nulling out unwanted ionospheric modes, was demonstrated by Friis and Feldman in 1937 [6]. The essence of these historic techniques, intended for intercontinental radio telegraph and radio telephone circuits, can still be found in modern HF radio communication systems, albeit in more elaborate forms.…”

Section: Introductionmentioning

confidence: 99%

The importance of circular polarization for diversity reception and MIMO in NVIS propagation

Witvliet

Maanen

Petersen

et al. 2014

The 8th European Conference on Antennas and Propagation (EuCAP 2014)

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Near Vertical Incidence Skywave propagation can provide High Frequency (HF: 3-30 MHz) radio coverage in an area of 300 by 300 km without the need for any intermediate infrastructure. It is therefore very well suited for disaster relief communication. However, electromagnetic waves refracted in the ionosphere are prone to fading caused by multipath propagation and by polarization change in the ionosphere. Historically, different diversity reception systems have been devised to reduce this fading. By contrast, modern HF Multiple Input Multiple Output (MIMO) techniques exploit the multipath aspects of the ionosphere to achieve an increased data throughput or a reduction of the required signal-to-noise ratio. The effectiveness of diversity reception and HF MIMO increases with decreasing correlation between the received signal streams. Electromagnetic waves propagating through the ionosphere consist of two characteristic wave components with circular polarization of opposite sense, the ordinary and extraordinary waves, each following a different path through the ionosphere. Adaptation of the polarization of the receive antennas to these characteristic waves provides two signal streams with high isolation. This is demonstrated with an experiment where both the ordinary and extraordinary wave are received separately. An isolation of at least 13 dB is shown.

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A Multiple Unit Steerable Antenna for Short-Wave Reception

Cited by 61 publications

References 9 publications

Observations of Cosmic Noise at 9·15 Mc/s

Observations of Cosmic Noise at 9·15 Mc/s

Reconfigurable H‐plane waveguide phase shifters prototyping with additive manufacturing at K‐band

The importance of circular polarization for diversity reception and MIMO in NVIS propagation

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