Ashraf Uz Zaman

Parallel Plate Cavity Mode Suppression in Microstrip Circuit Packages Using a Lid of Nails

The suppression of parallel plate and cavity modes in shielded microstrip circuits is presented. To this aim a textured metal lid consisting of periodically located pins known as a bed of nails is employed. The mode suppression has a bandwidth of more than 2:1, and it does not interfere much with the microstrip circuit. Thereby, this mode suppression technique introduces a new advantageous packaging technology for high frequency circuits.

Improved Microstrip Filters Using PMC Packaging by Lid of Nails

This paper shows that microstrip filters perform like textbook examples when packaged with perfect magnetic conductor (PMC). A PMC is made as a pin surface or lid of nails, and this is used to package a microstrip parallel coupled line bandpass filter. Our measurements confirm that parallel plate, cavity modes, and radiation are suppressed. This paper also includes a study of the reasons for a frequency shift between the ideal PMC packaged case and the realized case.

Design of a Simple Transition From Microstrip to Ridge Gap Waveguide Suited for MMIC and Antenna Integration

This letter describes a simple and low-loss microstrip-to-ridge gap waveguide transition with a very compact geometry. The transition transforms the electromagnetic (EM) fields from the microstrip mode to the air-filled ridge gap waveguide mode. This is achievable if the height of the air gap in the ridge gap waveguide is kept almost equal to the thickness of the substrate of the microstrip line. The transition has a pressure contact between the ridge and the microstrip line, so it works without soldering. This is advantageous in systems that require mechanically separable split-blocks or modules and need a lot of transitions. Experimental results of the manufactured back-to-back transition show an insertion loss of 0.32 dB and a return loss of 14.15 dB over 55% relative bandwidth in Ka-band.

Using Lid of pins for packaging of microstrip board for descrambling the ports of eleven antenna for radio telescope applications

This paper presents the packaging solution for the microstrip part of the descrambling section of dual polarized Eleven antenna. The packaging solution is based on using artificial Perfect Magnetic Conductor (PMC) shielding instead of conventional metal shielding. The PMC shielding is realized with a metal pin surface, and these metal pins force the parallel plate cavity modes to vanish within the frequency range of interest, from 5 GHz to 13.5 GHz.

Design of transition from coaxial line to ridge gap waveguide

This paper presents the design of a simple transition from ridge gap waveguide to coaxial line transition. First, a straight ridge gap waveguide with single transition on end is simulated. Then a ridge gap waveguide with two 90° bends is simulated with two transitions on each end. Available commercial FDTD simulation tool was used to design the transitions. A return loss of −10 dB was achieved over the frequency band of 12– 15.75 GHz.

Bed of Springs for Packaging of Microstrip Circuits in the Microwave Frequency Range

After the use of the bed of nails for removing cavity modes in microstrip circuit packages, we propose herein a new version of this periodic structure, based on helices (springs) instead of nails. This new structure, named bed of springs, is much more compact, and this allows its use at low frequencies where the bed of nails is not suitable as it is too bulky due to the required height of the nails (pins). The bandwidth of the proposed structure turns out to be similar to the case of bed of nails. Parametric studies are presented as a design tool and a demonstrator is manufactured and measured.

Investigation of a Microstrip-to-Ridge Gap Waveguide transition by electromagnetic coupling

A transition from Microstrip to Ridge Gap Waveguide (RGW) has been studied and numerically analyzed in terms of S parameters. The RGW technology shows potential to be used up to THz frequencies. Therefore, good transitions are needed in order to make possible the measurements of RGW components at frequencies above 100 GHz.

Wideband, lowloss, low-cost, quasi-TEM metamaterial-based local waveguides in air gaps between parallel metal plates

The paper presents a new waveguide appearing in the air gap between two parallel metal plates. One of the plates has a metal texture, and confined local waves follow ridges in the texture whereas they are prohibited from propagating in other directions by metal pins in the texture. The pins (or bed of nails) provide a high impedance surface that creates a stop band when used together with a metal surface, i.e. a parallel plate cut-off. The principle performance of the ridge gap waveguide is explained by numerical simulations of the dispersion diagram, both to show the parallel plate cut-off generated by the pin surface, but also to see the quasi-TEM wave propagating along the ridge. The performance is validated by numerical simulations and experimentally of a ridge gap waveguide with two 90 deg bends, including transitions to coaxial connectors. The ridge gap waveguide has a large potential for use up to THz because it can be realized without conducting joints between metal parts, and it lends itself to co-design and integration with active components.

Packaging of MMIC by using gap waveguide and design of a microstrip to ridge gap waveguide transition

In this work, gap waveguide based packaging technique is used to improve the isolation among critical microwave circuit components such as high gain amplifier chain. Amplifier chains at Ka-band were tested for a stable forward gain and it was found that-with gap waveguide packaging, 65~70dB of forward gain is achievable without the problem of self-resonance. Apart from the new packaging technique, a low-loss transition from microstrip to ridge-gap waveguide had been designed and tested. This transition is a key component to connect such amplifier chains to a planar slot array antenna. Experimental results for manufactured back to back transition show 14 dB return loss over 55% relative bandwidth from 2343GHz.

60-GHz Groove Gap Waveguide Based Wideband

Wideband design of power dividers, T-junctions, and transitions based on groove gap waveguide (GGW) technology is presented in this paper with the goal to use these components in high-gain millimeter-wave antenna array design at 60-GHz frequency range. Since this GGW technology does not require electrical contact between the different metal layers of a complex 3-D waveguide structure, the fabrication cost and mechanical complexity are decreased. The designed T-junctions and different power dividers exhibit wide operational bandwidth and low output power and phase imbalance over the 60-GHz frequency band. Also, two transitions from GGW to a standard rectangular waveguide have been designed. To validate the performance of the designed components, a 64-way power divider in combination with 256 radiating slots is designed, prototyped, and measured at 60-GHz band. Measurement results agree well with the simulated performance of the complete array antenna, and the antenna gain is more than 32.5 dBi. The total radiation efficiency is more than 80% over the operating frequency range from 57 to 67 GHz. Also, the measured sidelobe levels are found to be agreeing well with the simulated level.