Purpose: In microwave breast cancer detection, it is often beneficial to arrange sensors in close proximity to the breast. The resultant coupling generally changes the antenna response. As an a priori characterization of the radio frequency system becomes difficult, this can lead to severe degradation of the detection efficacy. The purpose of this paper is to demonstrate the advantages of adopting an interferometric multiple signal classification (I‐MUSIC) approach due to its limited dependence from a priori information on the antenna. The performance of I‐MUSIC detection was measured in terms of signal‐to‐clutter ratio (SCR), signal‐to‐mean ratio (SMR), and spatial displacement (SD) and compared to other common linear noncoherent imaging methods, such as migration and the standard wideband MUSIC (WB‐MUSIC) which also works when the antenna is not accounted for. Methods: The data were acquired by scanning a synthetic oil‐in‐gelatin phantom that mimics the dielectric properties of breast tissues across the spectrum 1–3 GHz using a proprietary breast microwave multi‐monostatic radar system. The phantom is a multilayer structure that includes skin, adipose, fibroconnective, fibroglandular, and tumor tissue with an adipose component accounting for 60% of the whole structure. The detected tumor has a diameter of 5 mm and is inserted inside a fibroglandular region with a permittivity contrast εr‐tumor/εr‐fibroglandular < 1.5 over the operating band. Three datasets were recorded corresponding to three antennas with different coupling mechanisms. This was done to assess the independence of the I‐MUSIC method from antenna characterizations. The datasets were processed by using I‐MUSIC, noncoherent migration, and wideband MUSIC under equivalent conditions (i.e., operative bandwidth, frequency samples, and scanning positions). SCR, SMR, and SD figures were measured from all reconstructed images. In order to benchmark experimental results, numerical simulations of equivalent scenarios were carried out by using CST Microwave Studio. The three numerical datasets were then processed following the same procedure that was designed for the experimental case. Results: Detection results are presented for both experimental and numerical phantoms, and higher performance of the I‐MUSIC method in comparison with the WB‐MUSIC and noncoherent migration is achieved. This finding is confirmed for the three different antennas in this study. Although a delocalization effect occurs, experimental datasets show that the signal‐to‐clutter ratio and the signal‐to‐mean performance with the I‐MUSIC are at least 5 and 2.3 times better than the other methods, respectively. The numerical datasets calculated on an equivalent phantom for cross‐testing confirm the improved performance of the I‐MUSIC in terms of SCR and SMR. In numerical simulations, the delocalization effect is dramatically reduced up to an SD value of 1.61 achieved with the I‐MUSIC in combination with the antipodal Vivaldi antenna. This shows that mechanical uncertainties are the main re...

Abstract-Antennas designed to link footwear sensors within body centric networks are introduced with two small UWB antennas, one directional and another quasi-omnidirectional. The radiating characteristics are evaluated for three positions on a sample sports shoe using a detailed simulation model and measurements with a homogenous foot phantom. Antenna performance is assessed for resilience to close proximity loading by the footwear materials and the phantom foot.

A compact, planar antenna operating at 433 MHz is proposed for wireless smart systems with dimensions of 51 × 28 mm 2 including a ground plane, and printed on a low-cost FR4 material. Significant size reduction is achieved using the variation of an inverted-F antenna configuration with a square-spiral section and rectangular patch element. Fine-tuning of the antenna's resonant frequency is possible using a small capacitive stub. Sensor and radio transceiver electronics can be accommodated above the ground plane. The measured results indicate a 10 dB return loss bandwidth of 4.5 MHz, and a peak realised gain of −13 dBi with omnidirectional radiation characteristics.Introduction: In recent years, wireless smart systems have rapidly emerged in areas such as healthcare and activity monitoring with applications in outpatient monitoring and the provision of in-home lifelines for the elderly [1, 2]. Wireless sensor motes operating in the 433 MHz industrial scientific and medical (ISM) band are a popular choice for low data rate applications and provide a good communication range due to reduced body absorption when compared to higher frequencies.Small and lightweight sensor realisations are key constraints for unobtrusive monitoring and an example of a 433 MHz sensor device is presented in [3] measuring 25 mm 2 in size excluding the antenna. A λ 0 /4 resonant antenna at 433 MHz would require dimensions of ∼170 mm excluding a ground plane. For the intended application, the goal is to realise a wrist-worn sensor with an area of 51 × 28 mm 2 . This size constraint means that a λ 0 /4 antenna is impractical and significant reduction of antenna dimensions is therefore necessary. It is well known however that decreasing the antenna size can negatively affect the efficiency, gain and bandwidth of the antenna [4]. Several small-sized 433 MHz antennas have been reported in the literature [5][6][7], but these antennas are too large in size for this application. A dual-band loop antenna configuration with dimensions very similar to those required is presented in [8] with a reported gain figure of −20 dBi at 433 MHz. In this Letter, an antenna structure is proposed that meets the required size constraints while also providing an acceptable figure for a peak realised gain of −13 dBi. The Letter discusses the design of the proposed antenna structure as well as size reduction methods. In addition, the simulated and measured results for the antenna impedance and radiation characteristics are presented and discussed.

In this study, the authors present a 36:1 relative bandwidth active front‐end low‐noise amplifier (LNA) with power limiter that has been developed for airborne ultra‐wideband receiver systems. The proposed system is driven by an external antenna with a balanced mode with an input impedance of 150 Ω. The whole microwave monolithic integrated circuit (MMIC) embeds a protection from the presence of high‐level signals, an ultra‐wideband amplifier circuit, an active balun and an impedance transformer. It has a bandwidth ranging from 0.5 to 18.0 GHz with 14 dB gain, 4.5 dB noise figure (NF), 20 dB common‐mode rejection and 30 dBm input overload protection. The circuit has a single bias from the output port greatly simplifying its use within a receiving system and can be directly integrated into the antenna mechanical support. Test measurements are also provided.

Abstract-This letter compares the propagation properties of Wireless Body Area Networks for three different locations (head, foot and waist) of the hub/internet gateway on the human body. The wireless channels between the hubs and four nodes (chest, back, and upper arms) are measured for frequencies between 5 and 7 GHz on a female and a male subject performing push-ups and squats. A framework using path gain and fade depth metrics in spider plots is used for cumulative performance description. The results show that the best overall performance is for a hub located on the temple and the worst overall performance is achieved for a hub on the waist. These results are expected to stimulate further research into the optimum hub placement on the human body.