This paper presents the development of a wideband dual-polarized 3D printed quad-ridged horn antenna (QRHA) that can be used for detecting and imaging applications. The QRHA consists of three main parts: the waveguide transducer, the horn, and the ridges. The waveguide transducer is modified into a square shape to obtain dual-polarization. Four variations of ridges were carried out to determine the ridge that best satisfies the required specifications, especially the bandwidth and sidelobe levels. Among the four ridge profiles, the quadratic model was used for the proposed QRHA as it generated the widest bandwidth and enhanced a lower operating frequency, which is beneficial for improving resolution and penetration depth. The double-ridged horn antenna (DRHA) was also investigated in order to make a comparison with QRHA’s performance. The characterization results show that when compared to DRHA, QRHA performs better in terms of bandwidth, beamwidth, gain, and side lobe suppression. Due to the benefits it provides, 3D printing based on polylactic acid (PLA) material was selected as the manufacturing process for the proposed QRHA. The fabricated QRHA had a weight that was three times lighter compared to conventional antennas. The measurement results indicate that the 3D printed QRHA has the wideband characteristics of a −10 dB working bandwidth of 7.9 GHz in frequency ranges of 3.5 GHz to 11.4 GHz. Isolation between the ridges below −20 dB was achieved for most frequency ranges. Co– and cross-polarizations were also performed to evaluate the dual-polarization of the proposed QRHA. The radiation patterns showed that the measurement results agree well with the simulations for low, middle, and high operating frequencies.

This paper discusses the investigation of bandwidth enhancement for microstrip rectangular patch antenna by putting up multiple slots etched on the patch. The technique is proposed in overcoming the nature characteristic of microstrip patch antenna which has narrowband bandwidth response. Here, the antenna is designed to work at center frequency around 1.6GHz for GPS application. The patch of antenna is fed by using a microstrip transmission line feeding network extended from a center pin of 500hm SMA connector. The number of slots etched on the patch is set to be 13 which are separated 3mm each other. The 13 slots which have different length for each are arranged in parallel with the feeding line. To shows the feasibility of proposed technique, the characteristics of microstrip patch antenna with multiple slots are compared to the conventional microstrip patch antenna. Both antennas are implemented using FR-4 Epoxy dielectric substrates with the dimension of 55mm × 80mm and the thickness of 1.6mm. From the characterization, although there are some slight differences of simulation and measurement results, in general the microstrip patch antenna with multiple slots demonstrates bandwidth enhancement up to 98.3% and 70.8% for simulated result and measured result, respectively.

This paper deals with an alternative technique for microstrip patch antenna miniaturization is investigated. The technique employs a 2 layer structures with an artificial magnetic conductor (AMC) structure used as the bottom layer replacing the ground plane. The AMC structure is constructed using a textured high impedance surface (HIS) that takes form of a doubly periodic square patches on top of a dielectric substrate. The miniaturization effect that is introduced especially in the reduction of patch size by use of this 2 layer structures will be numerically investigated. The proposed antenna is designed to have a resonant frequency of 2.45MHz suitable for wireless local area network (WLAN) application and is deployed on an FR-4 Epoxy substrate. To obtain the optimum design, numerical analysis is carried out using 3D simulation software. To verify the miniaturization effect, the proposed antenna will be compared to some reference antenna resonates at the same resonant frequency placed on a 2 layers FR-4 Epoxy substrate with the same thickness but without AMC structure. From the result, it is shown that the incorporation of AMC structure can reduce the size of antenna patch by more than 31%.

This paper presents a polylactid-acid (PLA) based 3D printed circularly polarized 2 × 2 X-band horn array antenna for circularly polarized synthetic aperture radar (CP-SAR) sensor. The use of CP horn array antenna is to overcome some issues related with mismatch orientation and ionospheric effect of linear polarization sensor. The proposed array antenna which is intended to operate at X-band frequency is realized using PLA material through 3D printing technique and fed by series sequential feeding network implemented on a 1.6mm thick NPC-F220A dielectric substrate. From the result, it shows that the proposed CP horn array antenna has 3dB axial ratio bandwidth more than 400MHz in X-band frequency range.

In this paper, a GNU Radio based software-defined FMCW (Frequency Modulated - Continuous Wave) radar is studied for weather surveillance application. The FMCW radar that has been gaining popularity due to the use of solid state microwave amplifier to generate a signal source is proposed for the design since the current weather surveillance radar is usually using a pulse-radar type that needs high power in pulse generation and high cost in the deployment. In addition, by using software-defined radar, therefore the designed FMCW radar can be implemented and configured at a reduced cost and complexity. The FMCW radar prototype is implemented using both open sources of software and hardware. The software part of the radar is realized using GNU Radio, whilst the hardware part is implemented using USRP (Universal Software Radio Peripheral) N210. Based on the design specification, an FMCW radar prototype based on GNU Radio is then realized and examined. From the performance-test, the prototype that works at a center frequency of 2.1GHz with a bandwidth of 750kHz is able to perform range detection of targets after utilizing the FFT (Fast Fourier Transform) function using MATLAB. In addition, the discussion of system design of software defined FMCW radar and performance-test of its prototype are presented.