S. Kanamaluru

Wide-band reduced-size uniplanar magic-T, hybrid-ring, and de Ronde's CPW-slot couplers

New reduced-size uniplanar magic-T and hybrid-ring coupler suitable for MICs and MMICs have been developed using a CPW-slotline ring that is 20% smaller than comparable designs. These circuits provide good amplitude and phase characteristics over a broad bandwidth. Experimental results show that the hybrid-ring coupler has a 1.3 octave bandwidth centered at 4 GHz and the magic-T has a bandwidth of 1.6 octave from 2-6 GHz. Both have a maximum power dividing imbalance of 0.4 dB and a 2.5/spl deg/ maximum phase imbalance. Also a new uniplanar de Rondes CPW-slot directional coupler was developed with good performance. The even-odd mode analysis of four-port networks with double symmetry was used to analyze this coupler. A de Rondes coupler with 5 dB coupling was designed and demonstrated over the frequency range of 2.4-3.4 GHz. The measurement results agree with the theoretical design.

Analysis and design of aperture-coupled microstrip patch antennas and arrays fed by dielectric image line

This paper presents the analysis and design of aperture-coupled microstrip patch antennas and arrays fed by an dielectric image line. A theory based on the cavity model of the microstrip patch antenna and the change in the modal voltage of the image line at the aperture was developed to analyze the single element aperture-coupled microstrip patch antenna. The theory developed was combined with the array theory to design linear traveling wave arrays at X-band and Ka-band frequencies. The required taper in the excitations of the individual patches of the array was achieved by varying the aperture dimensions. Experiments show very good results for the antennas and the arrays.

Aperture coupled microstrip antenna with image line feed

The paper presents an aperture coupled microstrip antenna with an image line feed operating at 10.5 GHz. The image line is terminated by a matched load. The back radiation resulting from the image line at the aperture is eliminated by the use of a reflector. The measured E-plane and H-plane patterns are very good showing very little cross-polarization (less than 18 dB). This structure has applications in passive linear arrays.<<ETX>>

Narrowband filter and annular slot antenna for PCS applications

A new narrowband filter has been developed for PCS applications. This filter has a 0.2 dB passband ripple bandwidth of 0.568% and is 60% smaller than the normal parallel coupled design. The filter can be integrated with the microstrip feedline of a novel annular slot antenna (ASA). The ASA has a 4.5% bandwidth and a planar structure. This antenna can be conveniently located on the chassis of a mobile PCS unit.

Ka-band aperture coupled microstrip antenna with image line feed

This paper presents a Ka-band microstrip antenna fed by dielectric image line. The image line is terminated by a short circuit. The antenna is coupled to the image line through the aperture in the common ground plane. The back radiation emanating from the image line is eliminated by the use of a metallic reflector. The design criteria (for 30 GHz operation) and the performance of the antenna are discussed. This structure is shown to have good potential for use at high frequencies.

Frequency tunable feedforward amplifier for PCS applications

A novel linear feedforward amplifier with channel tunability was developed for multicarrier wireless communications applications. This amplifier is designed to operate in the personal communication services (PCS) frequency range with a maximum output power of 27 dBm, and offers frequency selectivity by using variable attenuators and variable phase shifters in both the signal and error cancellation loops. The circuit is capable of achieving a variable tuning range of 195 MHz with an intermodulation cancellation of over 60 dBc, and the third point intercept point improvement of more than 15 dB.

Millimeter wave aperture coupled microstrip patch antenna arrays fed by dielectric image line

The large transmission losses in conventional microstrip feedlines that are used to feed aperture coupled microstrip patch antennas at millimeter wave frequencies can be avoided by using low loss transmission lines such as the dielectric image lines (DIL). This paper presents the analysis of the aperture coupled microstrip patch antennas fed by dielectric image lines (ACMADIL), design of antenna arrays of the new structure and the performance of the arrays.

Meander-image-line-feed microstrip antenna array for frequency-swept beam steering

This paper presents the design of a microstrip antenna array fed by a meander dielectric image line. The feeding line is meandered so as to increase the beam steering angle for a fixed bandwidth. The measurement results for two different antenna arrays are illustrated and discussed. The designed center frequency is 10 GHz.

Analysis of slot antenna with dielectric overlay fed by dielectric image line

This paper presents an analysis of slot antennas with or without a dielectric overlay fed by a dielectric image line. The power (reaction) at the aperture is determined using the Greens function in the spectral domain. This reaction and the change in modal voltage of the dielectric image line at the aperture are used to determine the impedance of the slot antenna. This analysis can be extended to slot antenna arrays fed by dielectric image lines that are useful at millimeter-wave frequencies.

Ka-band aperture coupled microstrip antenna array fed by modified insulated image line

This paper presents a Ka-band aperture coupled microstrip antenna array fed by modified insulated image line. A Kapton layer of lower dielectric constant and the same width as the image line is used to insulate the image line from the ground plane. Conductor loss and attenuation in the guide are reduced. The measured E-plane and H-plane radiation patterns show very good results with higher gain, lower side lobe levels, and narrow beam width for the 2 mm thick Kapton layer. This structure has good potential for use at millimeter wave frequencies.