Jong-Hoon Chun

A 3-D X-Band T/R Module Package With an Anodized Aluminum Multilayer Substrate for Phased Array Radar Applications

This paper presents the design and development of a compact 3-D transmit/receive (T/R) module with a selectively anodized aluminum multilayer package for X-band phased array radar applications. The proposed multilayer package consists of anodized aluminum substrates and vertical interconnects with embedded vias. The proposed package platform is based on thick anodized aluminum oxide layers and active bare chips directly mounted on bulk aluminum substrates for high electrical isolation and an effective heat sink. With its combination of thin-film embedded passive components and multilayer structure, the proposed module features a compact size of 20 mm × 20 mm, with a package height of 3.7 mm. To transfer radio-frequency (RF) signals vertically, we used coaxial hermetic seal vias with characteristic 50 Ω impedances and embedded anodized aluminum vias with a solder ball attachment and flip-chip bonding. The optimized vertical interconnect structure demonstrates RF characteristics with an insertion loss of less than 1.55 dB and a return loss of less than 12.25 dB over a broad bandwidth ranging from 0.1 to 10 GHz. The fabricated X-band 3-D T/R module has a maximum transmit output power of 39.81 dBm (9.5 W), a maximum transmit gain of 41.25 dB, and a receive gain of 19.15 dB over the 9-10 GHz frequency band. The RF-signal phase amplitude control is achieved by means of a 6 bit phase shifter with an rms accuracy of more than 5° and a gain setting range of 24 dB with an rms accuracy of more than 1.5 dB. The proposed multilayer aluminum package has the advantages of reducing the module size, decreasing the cost, and managing the thermal problem for X-band high-power T/R module package applications.

X Band 7.5 W MMIC Power Amplifier for Radar Application

An X-band MMIC power amplifier for radar application is developed using 0.25-μm gate length GaAs pHEMT technology. A bus-bar power combiner at output stage is used to minimize the combiner size and to simplify bias network. The fabricated power amplifier shows 38.75 dBm (7.5 Watt) Psat at 10 GHz. The chip size is 3.5 mm × 3.9 mm.

An X-band high power amplifier module package using selectively anodized aluminum substrate

In this paper, we made a high power amplifier module package using a selectively anodized aluminum substrate for the X-band radar T/R modules. The proposed solution of package is based on thick anodized aluminum oxide (Al2O3) layers and power chips mounted on aluminum for an effective heat sink. The fabricated high power amplifier module has a maximum output power of 39.49 dBm and maximum gain of 32 dB over 9-10 GHz frequency band. This package method can be further contributed to decreasing cost, reducing module size and managing thermal problem for the microwave high power T/R modules.

A Novel Geometrical Technique for Determining Optimal Array Antenna Lattice Configuration

We present a new 2D geometrical technique for determining optimal element arrangement for planar, phased array antennas with specified scan limits. This geometrical technique is not limited to conical or pyramidal scanning, but can be extended to any scan type that can be represented with an analytical equation. In addition, simple equations are given for two very important scanning types, conical and pyramidal. These equations provide deeper understanding and simpler graphical solutions than other pure graphical techniques. This paper discusses optimal array arrangement from the viewpoint of general lattice, which itself includes a hexagonal lattice as its subset. An important practical system, where this technique was found to be useful, is the N-face phased array antenna providing scanning throughout a hemisphere. Simple equations are given for determining the maximum off-axis scan and tilt angles of each face with respect to the zenith. Finally, the lattice arrangement of each face is decided by the new design technique.

Fabrication of the tile type transceiver module package for X-band phase array radar using selectively anodized aluminum substrate

In this paper, we proposed a tile type transceiver module package for X-band phase array radar system using a selectively anodized aluminum substrate. The proposed solution of package is based on thick anodized aluminum oxide (Al2O3) layers and bare chips mounted on aluminum for an effective heat sink. This package method can be further contributed to decreasing cost, reducing module size and managing thermal problem for the microwave high power T/R modules.

On the generalized villeneuve distribution

A new technique is presented for generating array factors with arbitrary sidelobe level and envelope taper. Aperture distribution corresponding to simple Taylor Distribution terminates abruptly in a pedestal at its edges. However, generalized Villeneuve distribution with proper excitation at the edges can be used to obtain array factor with desired sidelobe level and envelope tapering. The generalized Villeneuve distribution is obtained by root matching technique. If desired, an additional perturbation technique can be used to obtain more accurate results. A few examples are given to validate the presented method. Also, variation of different array characteristics with respect to sidelobe tapering is explained through graphical data.

A 28-dBm pHEMT Power Amplifier Using Voltage Combiner for K-Band Applications

A K-band power amplifier was implemented using a 0.25-mum pHEMT process. A tournament-shaped voltage combiner that combines power by combining voltage was used in the output matching network. The voltage combining method alleviates the drain voltage swing requirement of the power transistor, whose junction breakdown voltage becomes quite low especially for high frequency applications. The chip size of the designed power amplifier is only 2.52 mm2. The amplifier achieved a P1dB of 28.0 dBm. The measured linear gain was 25 dB at 23.1 GHz. These demonstrate the operation of the tournament-shaped voltage combiner at K-band.

Discrete Suppression with ΣΔ-STAP

This paper presents the hybrid algorithm of SigmaDelta-STAP and direct data domain(D3) which is robust to the discrete interferer. SigmaDelta-STAP provides high performance result with the relatively low complexity of calculation. It also requires small number of training sample to estimate covariance matrix. However this algorithm is vulnerable to the discrete interferer which is target-like interferer with high SNR. This paper shows that SigmaDelta-STAP can suppress discrete interferer signal in conjunction with direct data domain (D3) method which is an effective method to eliminate non-correlated interference such as discrete interferer in the non-homogeneous environment.

Non-statistical transformed data domain stap algorithm for non-homogeneous environment

This paper introduces a new non-statistical STAP algorithm which is efficient and powerful in non-homogeneous environment. The traditional statistical algorithms using the estimated interference covariance are not optimal in heterogeneous clutter. The non-statistical approach which uses primary data only and is appropriate to extremely heterogeneous case is presented. The transformed data domain (TDD) algorithm which is more simple and efficient compared to the original direct data domain (D3) algorithm is proposed. The received space-time signal is transformed to beam-doppler domain and weight to minimize interferences is obtained in this space. The performance of the proposed non-statistical STAP is tested in SIRV clutter model environment and compared to that of the approach which employs traditional statistical algorithm.