Another consideration is that it is easy to introduce a second microwave diode with a Gunn diode
when both are used as naked semiconductor die.
Harvey has a long history of system design for telecommunications, and for the last eight years has participated in the evolution of millimeter radios from Gunn diode
or multiplier-based FSK technology, through GaAs pHEMT MMIC-based linear radios.
Using a lower frequency FET oscillator and tripler eliminate the need for the more expensive, less reliable Gunn diode
Dielectric resonators are commonly used in microstrip oscillators and filters, in which their |TE.sub.01|Delta~~ mode is resonated.|2~ They are also available with a center hole, in which the E-field of this mode is practically zero, for attaching in microstrip filters with nylon screws, for example, or to integrate a Gunn diode
, as shown in Figure 2.
To demonstrate this technology for mm-wavelengths, a 37 GHz active notch antenna was built using a Gunn diode
on a 0.762 mm RT/duroid 5880 substrate.
In the configuration of the first active patch antenna,  a Gunn diode
was imbedded in a rectangular microstrip patch antenna.
The 46 to 64 GHz lumped-element Gunn VCO that was downconverted was varactor tuned at fundamental frequency, and output was obtained from the in-situ generated second harmonic frequency of the Gunn diode
.[1,2] A hyperabrupt junction GaAs varactor was used as the tuning element and contributed to the broadband linear tuning range exhibited by the VCO.
It has thereby enhanced the understanding of Gunn diode
and VCO operation and performance, and provided new opportunities in VCO and oscillator design to meet advanced system needs.
Nonlinear circuit analysis of Gunn diode
VCOs is quite difficult because of the presence of two non-linear devices coupled to each other.
are produced for mm-wave applications in large volumes, such as in radio links and door openers, and the technology is fairly mature today.
are used with patch antennas to realize space power combining oscillators.(1) In addition, frequency-agile microstrip antennas can be obtained with varactor diodes(2) and a photodiode can be set on the patch layer to demodulate the lightwave signal for optical fiber feeding.(3) Monolithic amplifiers have been integrated into patch antennas,(4)(5) and transistors have been used for low noise amplification(6) or for integrated oscillators.(7)
The RF power was generated using a sweep generator and harmonic multipliers up to 100 GHz, and Gunn diodes
with waveguide doublers for frequencies above 1 00 GHz.