A substrate integrated waveguide (SIW) cavity backed active slot antenna oscillator is proposed, the operation frequency of which can be tuned by means of a properly connected varactor. The cavity backed structure permits overcoming potential problems such as heat dissipation and unwanted surface wave modes in large array implementations, and may provide better phase noise performance. The use of SIW technology permits a cost-effective fabrication process and simple implementation at millimetre-wave frequency, for radar and communication applications. Full-wave FEM-based analysis is used for the design of the radiating structure, while harmonic balance and transient simulations are employed in the design of the active antenna oscillator and in the study of the stability of its steady-state solutions. Tunable active antenna prototypes have been implemented and measured.

Tunable SIW Cavity Backed Active Antenna Oscillator

A comparative performance study of rectangular and circular shape microstrip patch antennas at an X band frequency is presented in this paper. The resonant frequency is chosen at 10 GHz which is suitable for a variety of wireless applications. CST Microwave Studio is used as the software environment to design and compare the performance of the antennas. It is found that the rectangular patch antenna shows about 3.0 dB higher return loss than the return loss of circular patch antenna. In addition, the rectangular patch antenna has an improved VSWR value of 1.18 than that of the circular patch with VSWR 1.27. However, circular patch antenna offers about 8% higher bandwidth and nearly 2.0dB less side lobe power than that of rectangular patch antenna.

Comparative study of rectangular and circular microstrip patch antennas in X band

A hybrid technique that combines the method of moments (MoM) and the finite element method (FEM) to analyze cavity-backed patch antennas is presented This technique features the use of FEM in solving the electromagnetic field distribution in the cavity and the use of MoM in solving integral equations outside the cavity The results of MoM and FEM are combined through the continuity conditions on the boundary of the cavity Due to the flexibility of FEM, complex cavities filled with inhomogeneous media can be analyzed by this technique The results obtained by this hybrid technique are compared to the finite difference time domain (FDTD) results and good agreement is found >

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Theoretical modeling of cavity-backed patch antennas using a hybrid technique

This paper presents the design, manufacturing, and characterization of a wide-band cavity-backed aperture-coupled patch antenna and a 16-element antenna array on multilayer printed circuit board (PCB) targeted for D-band applications Microstrip line and grounded coplanar waveguide (GCPW) transmission lines are also designed and tested to investigate line losses at D-band The test structures are manufactured using printed circuit board technology with semi-additive processing (mSAP) of conductors on a multilayered substrate The measurement results indicate an insertion loss of 19 dB/cm for the microstrip line and 18 dB/cm for the coplanar waveguide at 150 GHz The measured maximum gains for single antenna and 16-element array are respectively 7 dBi and 14 dBi at 143 GHz The measured antenna input matching bandwidth is 20 GHz The results show the viability of advanced printed circuit technology for D-band transmission lines, antennas, and antenna arrays

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Patch Antenna and Antenna Array on Multilayer High-Frequency PCB for D-Band

An active antenna configuration is proposed for spatial-power-combining applications. The active patch antenna uses an inverted stripline topology to take advantage of several features. These features include avoiding drilling through the circuit substrate to insert the diode and the use of air within the resonant cavity to reduce loss. The inverted substrate serves as a radome for hermetic sealing. The active antenna and housing can be fabricated in modular form for reduced cost and easy replaceability of devices. The active inverted stripline patch antenna exhibits a much cleaner spectrum and greater stability than previously reported active antennas. The fixture serves as a ground plane, heat sink, and support in an active planar array or as a mirror in a quasi-optical power-combining resonator. A single active antenna operating at 9.23 GHz exhibited a 16-MHz locking bandwidth at 30-dB locking gain. Power-combining efficiencies of over 89% have been demonstrated for a four-element square array that maintained injection-locking and power-combining over a 60-MHz bias tuned bandwidth. Similarly, a four-element diamond array showed over 86% combining efficiency and 50-MHz bias tuned bandwidth. Beam steering was demonstrated by varying bias voltage to the individual antenna elements of the square array. >

Active inverted stripline circular patch antennas for spatial power combining

A circular patch antenna fed by an aperture-coupled microstrip line has been demonstrated at 29.3 GHz. The patch was enclosed by a cavity to reduce surface-wave interactions in an array environment and to improve heat dissipation when using active devices. The antenna exhibited a 2:1 input VSWR (voltage standing wave ratio) over a bandwidth of 12% from 27.52 to 30.95 GHz. The antenna should have applications in conformal phased arrays at millimeter-wave frequencies. >

A 29.3-GHz cavity-enclosed aperture-coupled circular-patch antenna for microwave circuit integration

A circular patch antenna fed by an aperture coupled microstrip line has been demonstrated. The patch was enclosed by a cavity to reduce the surface wave interactions in an array environment and to improve heat dissipation when using active devices. A pedestal design was also implemented to help heat dissipation when using active microwave circuits. The antenna exhibited a 9.3% bandwidth from 9.55 to 10.48 GHz. >

S. Sanzgiri

Papers

A 29.3-GHz cavity-enclosed aperture-coupled circular-patch antenna for microwave circuit integration

Performance of a 10 GHz circular patch antenna fed by an aperture coupled microstrip line