Pravinkumar,P A; Mohanan, P; K G Nair(Indian Journal of Radio & Space Physics, December , 1981)
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Abstract:
A technique for improving the coupling between a feed horn and reflector by using corrugated metallic flanges is presented.
Experimental data for flanges of varying parameters are given and theoretical explanation is supplemented
Mohanan, P; Pravinkumar,P A; K G Nair(Indian Journal of Radio & Space Physics, 1982)
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Abstract:
A simple technique for obtaining identical E- and H-plane patterns from E-plane sectoral feed horn is presented. Halfpower
beam width and gain of the antenna are also improved considerably. Experimental results for a number of horns with
flanges of various parameters are also presented. This system may find practical application in radar and space communication
systems
Zachariah,E J; Vasudevan, K; Pravinkumar,P A; Mohanan, P; K G Nair(Indian Journal of Radio & Space Physics, February , 1984)
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Abstract:
The design, erection and evalution procedures for it microwave anechuic chamber competed at Cochin University for
antenna studies are presented the chamber has an average reflectivity level of - 32 dB on at X-band frequencies, and it i,
comparable to international standards.
Mohanan, P; Aanandan,C K; K G Nair(Indian Journal of Radio & Space Physics, February , 1984)
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Abstract:
A modified H-plane sectoral horn antenna with identical E- and'H- plane.patterns over the X-band frequency is discussed.
This system has significantly reduced side lobes and hack lobes. Half=power beam width and gain of the antenna are also
improved with enhanced matching , Experimental results for a number of horns with various flanges are presented . These find
practical application for illuminating symmetric antennas like paraboloids and polarization measurements in radio
astronomy, etc. Compared to the fixed pyramidal horns. the present system offers great convenience in trimming the antenna
characteristics
Mohanan, P; Girijavallabhan, C P; Aanandan,C K; K G Nair(Indian Journal of Radio & Space Physics, February , 1984)
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Abstract:
A forward - biased point contact germanium signal diode placed inside a waveguide section along the E -vector is found to
introduce significant phase shift of microwave signals . The usefulness of the arrangement as a phase modulator for microwave
carriers is demonstrated. While there is a less significant amplitude modulation accompanying phase modulation , the insertion
losses are found to be negligible. The observations can be explained on the basis of the capacitance variation of the barrier layer
with forward current in the diode
Aanandan,C K; Mohanan, P; K G Nair(Department of Electronics, August 13, 1984)
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Abstract:
Design and development of a circularly polarized and matched H-plane sectorial horn antenna have been reported By
proper trimming of the flange parameters any desired polarization can be obtained from the horn
Aanandan,C K; Mohanan, P; K G Nair(IEEE Journals/ Transactions (USA), 1990)
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Abstract:
A microstrip antenna with large bandwidth is developed
using a parasitic technique . Compared to the available
wide-baud antennas,the proposed antenna structure is very
compact and gives a lessdistorted radiation pattern with frequency .
An impedance bandwidth,eight times that of a conventional patch
antenna of the same size, Isachieved. The concept of coupled microstrip
line model Is extended fortheoretical interpretation of the impedance loci
The design and development of an L-band printed dipole antenna.
optimized for wide-band applications near first resonance, is reported.
This design has achieved more than 48% impedance bandwidth
(VSWR 2:1), without degrading its overall radiation efficiency
K G Nair; Mohanan, P; Stephen, Rodrigues(Department of Electronics, 1991)
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Abstract:
Design and development of a new feed -horn antenna
with low sidelobe levels is reported . The E-walls of this
antenna are fabricated with low -loss dielectric substrate , periodically
loaded with thin conducting strips . The antenna is found
to be simulating the radiation characteristics of metallic corrugated
horns . This can be an ideal substitute for metallic corrugated
horns with added advantages like light -weight and low
production cost.
Design and development of a new feed -horn antenna
with low sidelobe levels is reported . The E-walls of this
antenna are fabricated with low -loss dielectric substrate ,
periodicallyloaded with thin conducting strips . The antenna
is found to be simulating the radiation characteristics of metallic
Corrugated horns . This can be an ideal substitute for metallic
Corrugated horns with added advantages like light -weight and low
production cost
Sangster,A J(Microwave and Optical Technology Letters, September , 1991)
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Abstract:
A new microstrip antenna element is described which exhibits polarization
agility. This is achieved by employing a T-slot radiator
which is driven by the edge fields of a balanced microstrip line. The
balanced line can support two propagating modes. namely. an even
mode and an odd mode, and be switching between these modes. the
orthogonal arms of the T-slot radiator are separately excited thus
forming orthogonally polarized radiated fields. A nucrostrip patch
antenna, which displays polarization agility using the sane mechanism,
is also described
Mohanan, P; K G Nair; Stephen, Rodrigues(Department of Electronics, November , 1991)
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Abstract:
Design and development of a new feed -horn antenna
with low sidelobe levels is reported . The E-walls of this
antenna are fabricated with low -loss dielectric substrate , periodically
loaded with thin conducting strips . The antenna is found
to be simulating the radiation characteristics of metallic corrugated
horns . This can be an ideal substitute for metallic corrugated
horns with added advantages like light -weight and low
production cost.
Hunagund,P V; Jose,K A; Mohanan, P; Nair, K G(Indian Journal of Radio & Space Physics, February , 1992)
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Abstract:
Results of exhaustive study of the effect of metallic flanges on H-plane radiation characteristics of V-slot
waveguide antenna are presented . It has been established that the beam can be sharpened or broadened by
varying the flange angle . The adjustment of the flange angle and flange width would further improve the
radiation pattern , yielding optimum efficiency from the flanged system
James, Kurian; Balakrishnan, K G; Nair, K G(IOP Publishing LTD, August 19, 1992)
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Abstract:
A simple and inexpensive power supply suitable for characteristics
studies of a klystron is described. The circuit is a modified form of the high voltage
adjustable power supply based on LM 317. This provides the necessary cavity and
repeller voltages over a wide range, with good regulation. The system is protected
aa- ainst short circuits and is ideallv suitable for laboratorv, ex.Deri ments with reflex
klystrons.
Ajaikumar,V; Jose,K A; Aanandan,C K; Mohanan, P; K G Nair(Microwave and Optical Technology Letters, October , 1992)
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Abstract:
Reduction of radar cross -section of dihedral corner reflectors using
simulated corrugated surface (.SCS) is reported. This technique is
found lo be more effective in the reduction of RCS or corner reflectors
for normal incidence . A typical reduction of 40-50 dB is
achieved using this method
Mohanan, P; Aanandan,C K; K G Nair(Department of Electronics, October , 1992)
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Abstract:
Reduction of radar cross -section of dihedral corner reflectors using
simulated corrugated surface (SCS) is reported. The technique is
found to be more effective in the reduction of RCS or corner reflectors
for normal incidence . A typical reduction of 40-50 dB is
achieved using this method.
Supriyo,Dey; Aanandan,C K; Mohanan, P; K G Nair(IETE Technical Review, 1993)
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Abstract:
Design, development and experimental observations of a L: band printed dipole antenna is presented.Bandwidth
enhancement is achieved by end-loading or the dipole arms. Using the present technique Impedance bandwidth van be
enhanced up to 50% without degrading the efficiency of the antenna.
Stephen,D S; Mathew,T; Jose,K A; Aanandan,C K; Mohanan, P; K G Nair(Department of Electronics, February , 1993)
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Abstract:
Simultaneous elimination of specular reflection and backscattered
power from a plane metallic surface by simulated
corrugated surfaces of constant period and variable strip
width for TM polarisation is reported. This new configuration
offers almost a ten-fold frequency bandwidth compared
with a regularly spaced strip grating of the same size.
Dey,S; Aanandan,C K; Mohanan, P; K G Nair(Department of Electronics, June , 1993)
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Abstract:
A circular miqrostrip antenna with a modified structure is
presented. By adjusting the feed location along the circumference
of the patch it is possible to match the antenna with a C
microstrip line of any impedance. The impedance bandwidth
and radiation characteristics are unaffected by this structural
V modification.
Ceramic dielectrics with high dielectric constant in the microwave frequency range are used as filters, oscillators [I], etc. in microwave integrated
circuits (MICs) particularly in modern communication systems like cellular telephones and
satellite communications. Such ceramics, known as 'dielectric resonators (DRs),donot
only offer miniaturisation and reduce the weight of the microwave components. but also
improve the efficiency of MICs