A Three Beam HF Phased Array Antenna Capable of Two Frequency Harmonic Operation

Abstract

The paper describes the design of a large HF phased array antenna which employs the principle of harmonic operation so that the same array antenna can be used at two harmonically related frequencies viz 18 and 9 MHz. This method avoids the necessity of using two large array antennas resulting in a substantial saving in cost and space. The array has centre fed dipole as elements and uses suitable techniques to achieve impedance matching at both the frequencies. The design of the feed system employing open wire transmission lines is also described.

Indexing terms:

• Phased array antenna
• Interlaced phased array
• Harmonic frequency
• Radiation pattern

Additional information

Notes on contributors

K V Janardhanan

K V Janardhanan born in March 1943, obtained BSc(Engg) in Electrical Engineering from the University of Kerala and ME in Applied Electronics and Servomechanisms from the Indian Institute of Science Bangalore in 1965 and 1967 respectively. He joined the Physical Research Laboratory (PRL), Ahmedabad in September 1967 and was transferred to the Vikram Sarabhai Space Centre (VSSC), Trivandrum in February 1970, where he has been working since then. He has extensive experience in the design and development of many VHF/HF radar systems used for ionospheric/atmospheric studies which include the 54.95 MHz backscatter radar, 18/9 MHz HF radar, the 54.95 MHz Meteor trail radar, all designed and developed in the Space Physics Laboratory (SPL) of VSCC and a multi-transmitter 50 MHz coherent radar system installed in the Institute of Space Research, Brazil. He and his team is presently developing a 2.5 MHz Partial Reflection Radar system to be operated at Thumba. His current areas of interest are Atmospheric radar systems, high power VHF/HF transmitters, Phased array antennas, coherent receivers etc.

K K Mukundan

K K Mukundan obtained B Tech in Electronics Engineering from Regional Engineering College, Calicut, Kerala in August 1985. He joined Space Physics Laboratory, Vikram Sarabhai Space Centre, Trivandrum in September 1985 as Scientist/Engineer SB. Since then he has been working on phased array antennas. He has designed and developed antenna systems for VHF radar working at 54.95 MHz and HF radar working at 18/9 MHz of Space Physics Laboratory. He is a member of the team who deviced a novel concept of feeding phased array antennas called Interlaced Phased Array (IPA) concept which reduces the number of feed points and phase shifters drastically. He has developed software for analysing and plotting radiation patterns of phased array antennas. Presently he holds the post of Scientist/Engineer SF in Space Physics Laboratory, VSSC.

K S V Shenoy

K S V Shenoy obtained BSc and Diploma in Electronics and Radio Engineering in the year 1963 and 1965 respectively. He joined the Indian National Committee for Space Research (INCOSPAR) as Technical Assistant in 1966 and worked on the development of a VHF radar transmitter. Later he was transferred to the Space Physics Division of Space Science and Technology Centre, Trivandrum, now known as Space Physics Laboratory Vikram Sarabhai Space Centre. He has designed and developed high power transmitter systems for VHF backscatter radar, mateor trail radar and HF radar of Space Physics Laboratory. Now he is the Engineer-in-charge of VHF backscatter radar being operated in Space Physics Laboratory for ionospheric studies.