Jayaseelan Marimuthu

This study compared portable ultra-wide band microwave system (MiS) versus body condition score to predict C-site fat depth, GR tissue depth and eye muscle depth (EMD) in lambs. Experiment 1 assessed MiS and condition score to predict ultrasound measured C-site and EMD (n = 1549). Precision and accuracy was greatest for the MiS measurement with liveweight included in the model, with a C-site predicted RMSEP of 0.58 mm, R2 0.60 and bias of 0.021 mm and an EMD predicted RMSEP of 2.27 mm, R2 0.72 and bias of 0.088 mm. Experiment 2 (n = 900) assessed pre-slaughter MiS scanning and condition scoring to predict carcase GR tissue depth, C-site fat depth and EMD. MiS performed better than condition score for all three carcase trait predictions, regardless of the inclusion of liveweight, with the highest precision and accuracy for GR tissue depth determination with a RMSEP of 3.68 mm, R2 0.63 and bias 0.072 mm.

A portable ultra-wide band microwave system (MiS) coupled with an open-ended coaxial probe (OCP) or Antipodal Vivaldi Antenna (VPA) was tested as a non-invasive objective measurement to predict beef carcase single site fat depth at commercial abattoirs. Experiment one tested the effectiveness of MiS coupled with a VPA. The VPA was used to predict hot carcase P8 (fat depth on the rump) across 4 slaughter groups (n = 241). The VPA was also used to predict cold carcase rib fat (at the quartering site, 75% along the rib eye muscle) across 5 slaughter groups (n = 598). Experiment two tested the ability of MiS coupled with OCP to measure hot carcase P8 across two slaughter groups (n = 435). A machine learning stacking ensemble method was used to create the prediction equations. Datasets were grouped by prediction trait (P8 or ribfat) and probe/antenna then randomly divided into 5 groups based on tissue depth. Precision was greatest using OCP to predict P8 fat depth with a RMSEP of 2.47 mm and R2 of 0.70. The VPA precision was similar for the two tissue depths assessed, hot carcase P8 had an average RMSEP of 2.86 mm and R2 of 0.58 compared to cold carcase rib fat RMSEP of 2.60 mm and R2 of 0.55.

The experiment evaluated the ability of portable ultra-wide band microwave coupled with a Vivaldi patch antenna to predict carcase C-site fat and GR tissue depth. For C-site, 1070 lambs, across 8 slaughter groups were scanned and for GR, 286 lambs across 2 slaughter groups. Prediction equations for reflected microwave signals were constructed with a partial least squares regression two-components model and a machine learning Ensemble Stacking technique. Models were trained and validated using cross validation methods in actual datasets and then in datasets balanced for tissue depth. The precision and accuracy indicators of microwave predicted C-site fat depth across pooled and balanced datasets were RMSEP 1.53 mm, R2 0.54, and bias of 0.03 mm. The precision and accuracy for GR tissue depth across pooled and balanced datasets were RMSEP 2.57 mm, R2 0.79 and bias of 0.33 mm. Using the AUS-MEAT fat score accreditation framework this device was able to accurately predict GR 92.7% of the time.

In this studies a prototype low cost portable handheld microwave system (MiS) designed and tested for back fat depth measurements using non-invasive techniques on lamb carcase in commercial abattoirs. For this application, two different type antennas was designed and tested. These results demonstrate the capacity of this prototype MiS system together with proposed antennas to estimate fat depth at the C site in lamb carcasses non-invasively in commercial abattoir at rate 100 carcase in 30 minutes.

Non-invasive and non-destructive measurements of fat depth are sought after within the beef industries, as overfat carcases cause significant economic loss and wastage for processors. Within the Australian beef industry fat depth is measured manually, however this has the disadvantage of being destructive, subjective and time-consuming [1]. Since biological tissues in animals, feature a high contrast in their dielectric properties (skin, fat, and muscle) at microwave frequencies [2], this represents an opportunity to different fat from lean and thus estimate fat depth and body composition of carcases and live animals. This concept has been tested in lamb carcases where a low-cost portable Microwave System has been developed for measuring C-site back fat depth [3]. This paper details the testing of a similar device in beef, where we hypothesised that it would accurately predict P8 and rib fat depth in beef carcases.

In the meat industries, overfat carcases cause significant economic loss due to the labour required for trimming fat, and the waste that it represents. Fat is the most variable component, both in its amount and distribution in the carcase, and on this basis the measurement of carcase fat depth is the cornerstone of most carcase classification schemes for beef, lamb and pork worldwide [1,2]. Fat depth is often measured manually, however this has the disadvantage of being destructive, subjective and time-consuming. The ability to estimate fat depth accurately via a non-invasive and non-destructive technique is therefore highly sought after [3]. One solution showing considerable promise for determining carcase fatness is a Microwave System (MiS) using low power non-ionizing electromagnetic waves [4]. Since biological tissues in animals, feature a high contrast in the dielectric properties (skin, fat, muscle and bone) at microwave frequencies [4], MiS can accurately evaluate the fat depth and body composition of carcases and live animals. As an illustration of tissue parameters, the range of contrast available in X-ray imagery within soft tissues is less than 2%; whereas within microwave electromagnetic fields the range in relative dielectric constant goes from a minimum of about 4 in fat to a maximum of about 70 in muscle [5]. Furthermore, the microwave devices required to produce and measure these fields are low cost and highly portable. Working within these constraints a low-cost portable Microwave System has been developed for measuring back fat depth in lamb carcases. This paper details early testing of this device, testing the hypothesis that it will provide a reliable estimate of back-fat depth in lamb carcases.

A low-cost reconfigurable microwave transceiver using software-defined radar is proposed for medical imaging. The device, which uses generic software-defined radio (SDR) technology, paves the way to replace the costly and bulky vector network analyzer currently used in the research of microwave-based medical imaging systems. In this paper, calibration techniques are presented to enable the use of SDR technology in a biomedical imaging system. With the aid of an RF circulator, a virtual 1-GHz-wide pulse is generated by coherently adding multiple frequency spectrums together. To verify the proposed system for medical imaging, experiments are conducted using a circular scanning system and directional antenna. The system successfully detects small targets embedded in a liquid emulating the average properties of different human tissues.

A novel compact bandpass filter (BPF) with multiple harmonics suppression is proposed. The device uses low impedance feeding network and one‐sixteenth wavelength coupled line loaded with open‐ended stepped‐impedance stubs. The structure generates eleven transmission zeros which enable realizing a sharp passband and wide stopband. Based on the proposed structure, two compact BPF of size around 10 mm× 20 mm on RT6010 substrate were designed, built, and tested. The two designs have fractional bandwidths of 32% (centered at 2.45 GHz) and 23% (centered at 2.8 GHz) with wide stopband extending from 3 GHz to more than 11 GHz with more than 15 dB of attenuation.

Microwave biomedical imaging has the potential to be a future complementary diagnostic technique for cost-critical situations. The accessibility and portability of diagnostic imaging can mean accurate information is available where it is needed. The feasibility of microwave imaging has been demonstrated by using lab equipment such as vector network analyzers, which, whilst they are accurate, they are also large and expensive. Capturing the required signal responses can instead be performed by using software defined radio (SDR) technology, which due to its high manufacturing volumes can have a cost which is several orders of magnitude lower than a VNA. Although the performance of such a system might be lower than that of a full-sized VNA, the performance is still adequate for biomedical imaging applications. In this paper, an SDR-based system's performance is analyzed and shown to accurately detect an abnormality within a head phantom.

Microwave medical imaging is an attractive complement to current diagnostic tools for medical applications due to its low-cost, portability and non-ionization radiation. In this paper, generic software defined radio (SDR) technology is used to perform biomedical measurements, paving the way for low-cost, compact and reconfigurable imaging systems. SDR technology is capable of wide band instantaneous spectrum capture, in our case 20 MHz at a time in the 0.3 - 3.8 GHz band. To provide the resolution required in medical imaging, it needs to combine multiple frequency spectrums together. Using this as the basis of the system, a cylindrical scanning system and directional antenna are used to measure a biological phantom with multiple targets inside. The system is able to detect the two targets with varying spacing.