Analytical Performance of Low Noise Amplifier Using Single-Stage Configuration for ADS-B Receiver

Automatic dependent surveillance-broadcast (ADS-B) is an equipment of a radar system to reach difficult areas. For radar applications, an ADS-B requires a low noise amplifier (LNA) with high gain, stability, and a low noise figure. In this research, to produce an LNA with good performance, an LNA was designed using a BJT transistor 2SC5006 with DC bias, VCE = 3 V, and current Ic = 10 mA, also a DC supply with VCC = 12 V, to achieve a high gain with a low noise figure. The initial LNA impedance circuit was simulated using 2 elements and then converted into 3 elements to obtain parameters according to the target specification through the tuning process, impedance matching circuit was used to reduce return loss and voltage standing wave ratio (VSWR) values. The LNA sequence obtains the working frequency of 1090 MHz, return loss of -52.103 dB, a gain of 10.382, VSWR of 1.005, a noise figure of 0.552, stability factor of 0.997, and bandwidth of 83 MHz. From the simulation results, the LNA has been successfully designed according to the ADS-B receiver specifications.

Sinuous Antenna for UWB Radar Applications

In this paper, the recent progress on sinuous antennas is detailed, focusing the attention on the antenna geometry, dielectric structure, and miniaturization techniques. In the first part, we introduce the basic principles of the frequency-independent antenna, in particular the self-complementary and log-periodic geometries, as well as the antenna geometries, all characterized in terms of angles. The operating principles, main advantages, system design considerations, limits, and challenges of conventional sinuous antennas are illustrated. Second, we describe some technical solutions aimed to ensure the optimal trade-off between antenna size and radiation behavior. To this aim, some special modification of the antenna geometry based on the meandering as well as on the loading with dielectric structures are presented. Moreover, the cavity backing technique is explained in detail as a method to achieve unidirectional radiation. Third, we present a new class of supershaped sinuous antenna based on a suitable merge of the 2D superformula and the sinuous curve. The effect of the free parameters change on the antenna arm geometry as well as the performance improvement in terms of directivity, beam stability, beam angle, gain, and radiating efficiency are highlighted.

On Dispersion and Multipath Effects in Harmonic Radar Imaging Applications

In harmonic radar applications, images produced using algorithms of conventional radar applications experience some defocusing effects of the electronic targets’ impulse responses. This is typically explained by the dispersive transfer functions of the targets. In addition, it was experimentally observed that objects with a linear transfer behavior do not contribute to the received signal of a harmonic radar measurement. However, some signal contributions based on a multipath propagation can overlay the desired signal, which leads to an undesired and unusual interference caused by the nonlinear character of the electronic targets. Here, motivated by the analysis of measured harmonic radar data, the effects of both phenomena are investigated by theoretical derivations and simulation studies. By analyzing measurement data, we show that the dispersion effects are caused by the target and not by the measurement system or the measurement geometry. To this end, a signal model is developed, with which it is possible to describe both effects, dispersion and multipath propagation. In addition, the discrepancy between classic radar imaging and harmonic radar is analyzed.

A Hybrid Antenna with Equal Beamwidth in Two Frequency Bands for Radar Applications

This paper presents a novel hybrid antenna with equal beamwidth in two frequency bands for short-range radar applications. The proposed design consists of a 2 × 2 patch array and a SIW-fed dielectric rod antenna. The two kinds of radiators are responsible for the 5.8 GHz and 24 GHz ISM bands, respectively. Pencil beams are obtained in both lower and upper bands. The beamwidth generated by the dielectric rod can be flexibly tuned to coincide with that of the patch array. Magneto-electric (ME) dipole, composed of a slot and two parasitic monopoles, is constructed to replace the conventional 3-D waveguide feeder, which can excite the dielectric rod effectively. The complementary structure is helpful to obtain a pencil beam. The 2 × 2 patch array has the size of 70 × 70 mm2 and is fed by a four-way power divider. Due to no overlapping radiating aperture, the two radiators can work independently with high port isolation. The measured peak gain in the two bands is 12.5 dBi and 12.7 dBi. The measured 3-dB beamwidth at 5.8 GHz and 24 GHz is 42° and 39° in x-z plane, and 43° and 42° in the y-z plane. The proposed antenna features a small beamwidth difference in two frequency bands, thus being attractive for dual-band radar systems.