10
S. Kar
to the IMPATT diode in such an integrated power module may be done by attaching
gold ribbons to the ground plane and the cap structure as indicated in Fig. 7, via
bonding pad especially for the disc structure. This will not affect the electromagnetic
functioning of the module and also the radiation from the antenna (as E-field in
the resonant-cap cavity will be perpendicular to the metallic ribbons and since the
radiation field being transverse to the upper surface of the slotted resonant-cap disc, it
will be unaffected by the presence of the metallic ribbons). Finally, the power module
may have to be packaged in some form or the other in some innovative way—which
may be decided as and when the power module design and testing is completed. At
first, we need to proceed for the proof of principle with physical conceptualization,
analysis, simulation, optimization, and finally, the fabrication of the diode chip and
the integrated module and its experimental testing would establish the success of the
proposed integrated power module.
Here, the antenna (improvised microstrip patch type) needs no transmission
line/waveguide to connect to the oscillator as it is integrated with the oscillator (with
IMPATT device embedded in the improvised resonant-cap cavity); thus, transmission
loss is minimized. This is an important advantage of the integrated device-antenna
module because at THz frequency, power available from the device is inherently low.
Further, the integrated structure will lead to size miniaturization too. Unlike conventional feeding mechanism in microstrip patch antenna (coaxial feed, microstrip feed,
aperture feed, etc.), here the IMPATT source directly feeds input to the improvised
microstrip patch antenna and the IMPATT diode is fed with the reverse bias with
gold ribbons attached to the slotted disc via bonding pads and soldered to the ground
plane as shown in Fig. 7.
3 Analytical Modelling to Realize the Power Module
The analytical modelling will begin with the analytical characterization of resonantcap cavity, followed by device-circuit interaction and hence the oscillator characterization and finally to evaluate the radiation characteristics of the improvised
slotted-disc microstrip patch antenna of the power module.
3.1 Analytical Characterization of Resonant-Cap Cavity
It has already been mentioned that the lower face of the metallic disc of the cap structure and the upper face of the lower broad wall of the waveguide (or the ground plane
of the improvised microstrip patch antenna of the integrated power module) forms
the resonant-cap cavity. In such a cavity, formed between two circular conducting
plates parallel to each other, electromagnetic energy is guided radially with no field
variations either in the circumferential or axial direction. Thus, there will be only field
S. Kar
to the IMPATT diode in such an integrated power module may be done by attaching
gold ribbons to the ground plane and the cap structure as indicated in Fig. 7, via
bonding pad especially for the disc structure. This will not affect the electromagnetic
functioning of the module and also the radiation from the antenna (as E-field in
the resonant-cap cavity will be perpendicular to the metallic ribbons and since the
radiation field being transverse to the upper surface of the slotted resonant-cap disc, it
will be unaffected by the presence of the metallic ribbons). Finally, the power module
may have to be packaged in some form or the other in some innovative way—which
may be decided as and when the power module design and testing is completed. At
first, we need to proceed for the proof of principle with physical conceptualization,
analysis, simulation, optimization, and finally, the fabrication of the diode chip and
the integrated module and its experimental testing would establish the success of the
proposed integrated power module.
Here, the antenna (improvised microstrip patch type) needs no transmission
line/waveguide to connect to the oscillator as it is integrated with the oscillator (with
IMPATT device embedded in the improvised resonant-cap cavity); thus, transmission
loss is minimized. This is an important advantage of the integrated device-antenna
module because at THz frequency, power available from the device is inherently low.
Further, the integrated structure will lead to size miniaturization too. Unlike conventional feeding mechanism in microstrip patch antenna (coaxial feed, microstrip feed,
aperture feed, etc.), here the IMPATT source directly feeds input to the improvised
microstrip patch antenna and the IMPATT diode is fed with the reverse bias with
gold ribbons attached to the slotted disc via bonding pads and soldered to the ground
plane as shown in Fig. 7.
3 Analytical Modelling to Realize the Power Module
The analytical modelling will begin with the analytical characterization of resonantcap cavity, followed by device-circuit interaction and hence the oscillator characterization and finally to evaluate the radiation characteristics of the improvised
slotted-disc microstrip patch antenna of the power module.
3.1 Analytical Characterization of Resonant-Cap Cavity
It has already been mentioned that the lower face of the metallic disc of the cap structure and the upper face of the lower broad wall of the waveguide (or the ground plane
of the improvised microstrip patch antenna of the integrated power module) forms
the resonant-cap cavity. In such a cavity, formed between two circular conducting
plates parallel to each other, electromagnetic energy is guided radially with no field
variations either in the circumferential or axial direction. Thus, there will be only field