Kirti Dhwaj

A compact branch line coupler using novel periodically grounded slow-wave structure

This paper describes a branch line coupler using novel periodically grounded slow-wave transmission line (PG-SW-TL). The slow-wave characteristics is achieved by periodically placed through-via-holes (TVH). Compared with conventional cross-tie SW-TL, the proposed transmission line is easy to implement as a branch or a bend. In addition, it is easy to manufacture as it does not require blind-via-hole (BVH). The measurement results of the fabricated branch line coupler using PG-SW-TL for L-band demonstrate reducing 50.3 % of area.

Blazed metasurface grating: The planar equivalent of a sawtooth grating

The blazing behavior of non-planar sawtooth gratings are mimicked with a planar metasurface. We show that with an appropriate design, an equivalent planar “blazed metasurface” can reflect most of the incident power back in the path of incidence, and with reduced power reflected in the specular direction. We then utilize such metasurface to create high rejection stopband in a waveguide, by lining the sidewall of the guide with this metasurface. The results are justified by theory, as well as simulations and measurements. The blazed metasurface may find various applications in microwaves up to optical frequencies, e.g. for stopband filters, Fabry-Perot resonator mirrors, or replacing corner reflectors.

A Novel Fully Synthesizable All-Digital RF Transmitter for IoT Applications

In this paper, a fully synthesizable all-digital transmitter (ADTX) is first proposed. This transmitter (TX) uses Cartesian architecture and supports wide-band quadratic-amplitude modulation with wide carrier frequency range. Furthermore, the design methodology for ADTX and corresponding bandpass filter is discussed. This TX is synthesized with digital register transfer level-graphic database system flow, and can be easily implemented in any standard CMOS technology. An exemplary TX is synthesized by TSMC 28-nm standard cell library with extremely small area (0.0009 mm2) and supports carrier frequency as high as 6 GHz with excellent error vector magnitude (<−30 dB). To the best of the authors’ knowledge, this is the first work on a fully synthesizable design of RF transistors, allowing easy technology migration and portability.

Cavity Resonators Do the Trick: A Packaged Substrate Integrated Waveguide, Dual-Band Filter

The 2015 Microwave Theory and Techniques Society (MTT-S) International Microwave Symposium in Phoenix, Arizona, played host to a total of 16 student design competitions. One of these, sponsored jointly by the MTT-12 Technical Committee on Microwave and Millimeter-Wave Packaging and Manufacturing and the MTT-8 Technical Committee on Filters and Passive Components, was based on the design of a substrate integrated waveguide (SIW) dual-band filter.

Half-Mode Cavity-Based Planar Filtering Antenna With Controllable Transmission Zeroes

A two-pole half-mode substrate integrated waveguide (HMSIW) cavity-based filtering antenna is presented. The HMSIW cavity is used as a radiating resonator with a conventional substrate integrated waveguide (SIW) cavity functioning as a high-

Microstrip diplexer with low channel-frequency ratio

Q

An electronically switchable wideband pattern diversity antenna

resonator of the filter, leading to its compact size. The concept of source-load coupling is introduced for filtering antennas, which allows for the presence of two controllable transmission zeroes (TZs) in the frequency response of proposed design. This is accomplished by using electric coupling between two resonator cavities and a combination of microstrip/coaxial line to feed the antenna. The single-layer printed circuit board structure provides a broadside gain of 4.3 dBi at the operating frequency of 5.5 GHz. Gain curves are plotted at the broadside of the antenna, clearly showing a quasi-elliptic response and a 3-dB bandwidth of 2.6%.

Tunable transmission zeroes bandpass filter with external quality factor control

The paper presents a microstrip diplexer constructed by joining two stub-perturbed ring resonators at a T-junction. Each ring resonator acts as a bandpass filter with a transmission zero lying very close to the passband of the other filter, thereby increasing the isolation between the two channels. A short stub is additionally added at the T-junction to improve the matching at the common port. The diplexer is able to achieve a channel separation of 50 MHz, with the two channels centered at 2.49 GHz and 2.37 GHz respectively. This translates to a center frequency ratio of 1.05 between the two channels, which is the smallest amongst the published works. The insertion loss in both the channels is below 2.4 dB. The return loss at the three ports is around 20 dB, with the in-band channel isolation being greater than 20 dB.

Transmission-line equivalent and microstrip structure for planar Möbius loop resonator

A wideband pattern diversity antenna operating at 5.5 GHz is proposed. The antenna is a monopole radiating element with two orthogonal feeds. The antenna has a bandwidth of 90%, over which the radiation patterns are consistent. A broadband phase shifting network is integrated with the antenna. Single pole double throw (SPDT) switches are used with the phase shifting network to electronically control radiation pattern of the antenna. Consistent diversity performance is achieved in terms of the radiation pattern by the integrated system over the entire bandwidth as that of the antenna.

Broadband high gain SIW ring slot antenna

A methodology to control the frequency transmission zeroes (FTZs) of a dual-mode resonator based elliptic-response filter is presented. Varactor loaded feeding structures are introduced for exciting a stub-perturbed ring-resonator to control the external quality factors associated with even and odd modes of the resonator. The technique allows for control of FTZs on either sides of the passband without any significant change in the bandwidth or operating frequency of the filter. Because of the high-Q nature of ring resonator, assymetric frequency responses are achieved with an in-band insertion loss <2.9 dB and out-of-band suppression >55 db at 190 MHz from the center-frequency of 2.2 GHz. Additionally, the filter is provided with tunable source-load coupling to isolate the movement of two FTZs.