K.G. Nair

Broad-band gap coupled microstrip antenna

A microstrip antenna with large bandwidth is developed using a parasitic technique. Compared to the available wideband antennas, the proposed antenna structure is very compact and gives a less distorted radiation pattern with frequency. An impedance bandwidth eight times that of a conventional patch antenna of the same size is achieved. The concept of coupled microstrip line model is extended for theoretical interpretation of the impedance loci. The experimental procedure and results are described, and a theoretical analysis is presented. >

Analysis of a new compact microstrip antenna

A new compact microstrip antenna element is analyzed. The analysis can accurately predict the resonant frequency, input impedance, and radiation patterns. The predicted results are compared with experimental results and excellent agreement is observed. These antenna elements are more suitable in applications where limited antenna real estate is available.

Bandwidth enhancement by flared microstrip dipole antenna

The authors present the results of a detailed experimental investigation exploring the possibility of improving the impedance bandwidth of a printed dipole antenna. This configuration can give considerable enhancement of impedance bandwidth without adversely affecting the efficiency of the antenna. Specifically, the new microstrip version of the FMDA (flared microstrip dipole antenna) has a bandwidth twice that of a conventional dipole antenna. This enhancement in the bandwidth is not accompanied by any losses. It is noted that this compact broadband microstrip dipole is a substitute for conventional dipoles in phased-array antennas for terrestrial applications.<<ETX>>

Single‐feed dual‐frequency dual‐polarized slotted square microstrip antenna

A novel dual frequency dual-polarized square microstrip patchantenna embedded with a slot is presented. The proposed antenna offers tunability of the frequency ratio between the two frequencies by adjusting theslot dimensions. This configuration also provides a size reductionup to -51 and 35% for the two modes as compared to a square microstrip patch antenna. ® 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 25: 395-397, 2000.

DIELECTRIC -RESONATOR -LOADED MICROSTRIP ANTENNA FOR ENHANCED IMPEDANCE BANDWIDTH AND EFFICIENCY

A new method for enhancing the 2.1 VSWR impedance bandwidth of microstrip antenna s is presented. Bandwidth enhancement is achieved by loading the microstrip antenna by a ceramic microwave dielectric resonator (DR). The validity of this technique has been estab- lished using rectangular and circular radiating geometries. This method improves the bandwidth of a rectangular microstrip antenna to more than 10% (= 5 times that of a conventional rectangular microstrip antenna ) with an enhanced gain of I dB.

Theoretical analysis of compact and broad-band microstrip antenna with gap-coupled parasitic elements along the non-radiating edges

Wideband performance has been obtained from a microstrip patch antenna by using parasitic patches coupled along the nonradiating edges. The concept of the coupled microstrip line model is extended for the theoretical interpretation of the input impedance of a two-patch gap coupled along the nonradiating edges. It is concluded that the theory presented here predicts the impedance behavior of a rectangular patch antenna loaded with a parasitic element within tolerable limits.<<ETX>>

A broadband low profile microstrip circular patch antenna

A new broadband and compact microstrip antenna design has been proposed. This design gives good impedance bandwidth of the order of 10%. The new conformal antenna requires a smaller area compared to an ordinary corresponding circular patch antenna.

A strip-loaded feed-horn antenna

The design and development of a feed-horn antenna with flow sidelobe and low cross-polarization levels are reported. The E-walls of this antenna are fabricated with low-loss dielectric substrate, periodically loaded with thin conducting strips. The antenna simulates the radiation characteristics of metallic corrugated horns. This can be an ideal substitute for metallic corrugated horns, having added advantages like light weight and low production cost.<<ETX>>

Reduction of radar cross section of corner reflectors using strip grating technique

A simple and effective method to reduce the radar cross section (RCS) of a dihedral corner reflector is presented. The RCS of a corner reflector loaded with periodic conducting strips over a dielectric sheet is determined experimentally and is compared with that from the reference target. A typical reduction of 20-30 dB for TE (transverse electric) polarization is shown. The large echo due to the mutual perpendicularity of the two flat surfaces in corner reflector is found to be reduced for TE polarization using the strip grating technique.<<ETX>>

Simulated corrugated feed horn antenna

A technique for developing a new type of feed horn with the same radiation characteristics as a metallic corrugated horn is presented. This horn antenna with low back and sidelobe levels can be used as a substitute for a metallic corrugated horn with added advantages of high gain, low cross polarization, low cost, and light weight. The convenience of the photolithographic technique for fabricating simulated corrugated surfaces opens the possibility of the mass production of such horns with simpler methods.<<ETX>>