Ronald H. Johnston

Cardiac and Behavioral Responses of Mountain Sheep to Human Disturbance

Telemetered heart rates (HR) and behavioral responses of mountain sheep (Ovis canadensis canadensis) reacting to human disturbance in the Sheep River Wildlife Sanctuary, southwestern Alberta, were recorded. Cardiac and behavioral responses of sheep (4 ewes, 1 ram) to an approaching human were greatest when the person was accompanied by a dog or approached sheep from over a ridge. Reactions to road traffic were minimal as only 8.8% of vehicle passes elicited HR responses. No reactions to helicopters or fixed-wing aircraft were observed at distances exceeding 400 m from sheep. Responses to disturbance were detected using HR telemetry that were not evident from behavioral cues alone. However, mean duration of the HR response (138.6 sec) was not greater (P > 0.05) than mean period of the behavioral reaction when sheep were alert or withdrawing from harassing stimuli (112.4 sec). Use of HR telemetry in harassment research is discussed. J. WILDL. MANAGE. 46(2):351-358 Survival and optimal use of habitat by individuals demand high levels of vigilance so that stimuli indicating presence of predators, conspecifics, food, or shelter do not go undetected (Dimond and Lazarus 1974). Yet if an animal is excessively aroused, as from human disturbance, the added cost of excitement may interfere with health, growth, and reproductive fitness (Geist 1979:5). Recent studies of free-living birds (Kanwisher et al. 1978) and ungulates (Ward et al. 1976, MacArthur et al. 1979) have revealed that heart rate is a sensitive indicator of arousal, the first stage of an alarm reaction to stress (Jenkins and Kruger 1975). These and other investigations (Thompson et al. 1968, Cherkovich and Tatoyan 1973, Moen et al. 1978) have demonstrated consistent HR responses to disturbing visual or auditory stimuli, often in the absence of overt behavioral changes. Expanding upon earlier work (MacArthur et al. 1979), the present paper integrates cardiac and behavioral observations to better understand how individuals in a population of mountain sheep perceive and respond to environmental perturbations. In view of escalating use of alpine areas by hikers, particular attention is focused on the sensitivity of sheep to approaches by humans (Dunaway 1971). The study also addresses relative merits of HR telemetry and overt behavioral observations as methods for detecting and defining harassment responses in ungulates. Preliminary findings (MacArthur et al. 1979) suggested cardiac responses may persist longer than behavioral reactions, and a quantitative comparison of these 2 indices of disturbance is reported here. We acknowledge the field assistance of D. MacArthur, B. Horejsi, G. Lynch, J. Jorgenson, D. Olsen, and D. Nugent. We thank the technical staff of the Department of Electrical Engineering, University of Calgary, for constructing transmitters and other electronic equipment essential to this study. Cooperation provided by the Alberta Forest Service and Alberta Fish and Wildlife Division is also appreciated. Financial support was proIPresent address: Department of Zoology, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada. J. Wildl. Manage. 46(2):1982 351 This content downloaded from 157.55.39.180 on Mon, 25 Apr 2016 06:15:48 UTC All use subject to http://about.jstor.org/terms 352 RESPONSES OF MOUNTAIN SHEEP TO DISTURBANCE* MacArthur et al. vided by the Natural Sciences and Engineering Research Council of Canada, and by the Foundation for North American Wild Sheep.

Evaluation of a lossless combiner in a LINC transmitter

Two combiners are compared for use in a LINC transmitter. Most LINC transmitters use matched hybrid combiners as they provide high isolation between input ports to provide undistorted signal combining. A tee combiner has also been explored for use in a LINC transmitter but was evaluated under the assumption of high input port isolation and perfectly matched amplifier outputs. This paper evaluates the use of a lossless tee combiner with input port coupling and unmatched amplifier outputs and their effects on the LINC transmitters linearity and efficiency. It is shown that efficiency may be improved at the expense of overall transmitter distortion when a lossless tee combiner is used.

Compact antenna for Radar-based breast cancer detection

Microwave imaging for breast cancer detection is based on the contrast in electrical properties of healthy fatty breast tissues and malignant tumors. This inherent contrast causes microwave reflections from tumors embedded in normal tissues. Radar-based breast imaging detects tumors by observing variations in microwave signals reflected from the tumors as the antenna location changes. The topics of this paper are the development of a compact antenna for the detection of cross-polarized reflections and the application of this antenna to radar-based breast cancer detection. The antenna is designed, simulated, constructed and measured. The capabilities and limitations of the antenna for detecting tumor models are investigated through simulation and experiments, demonstrating the potential of this method for the detection of tumors in the breast.

A new aperture coupled microstrip slot antenna

A new aperture coupled design is proposed for microstrip slot antennas to improve their radiation performance. The proposed design is based on a new aperture coupling technique in which the slot is fed by a microstrip line and coupled to several parasitic patch radiators etched on the opposite side from the slot. In contrast to the combination of a slot and a microstrip patch in conventional aperture coupled microstrip antennas, the patches here are employed to reduce the radiation into the half-space that they occupy and increase the radiation in the other half-space. Therefore, the slot antenna can produce radiation patterns with a high front-back ratio. The above objective is achieved by optimizing standing wave distributions of the aperture electric field in the slot through the adjustment of the position of the patches along the axis of the slot. In this paper, design considerations are given, and the results are validated by numerical simulations and experimental measurements.

A Holographic Antenna Approach for Surface Wave Control in Microstrip Antenna Applications

A holographic antenna inspired structure is used to control the surface wave (SW) excited by a microstrip patch antenna. The hologram is designed to support a periodic leaky-wave which radiates at broadside and enhances the radiation of the patch while suppressing the horizontal lobe. In this design, the holographic approach is adapted for patch antenna applications where the SW wavelengths are comparable to the freespace wavelength. This is achieved by introducing dual phase-shifting metallic dipoles with periodic spacings. This paper discusses a simple and intuitive design method for the holographic surface, as well as its integration with the microstrip patch. The initial design concept was developed by assuming small perturbation to the SW, which was subsequently verified through full-wave simulations and prototype measurements. The results verified the improvements in the broadside gain and SW efficiency of the microstrip patch at the cost of increased area.

Compact Independent Dual-Band Hybrid Resonator Antenna With Multifunctional Beams

This paper presents a new compact independent dual-band hybrid resonator antenna with multifunctional beams. The proposed antenna uses the combination of a thin circular disk dielectric resonator (DR) and a T-shaped microstrip line. In this configuration, the T-shaped microstrip line performs the functions of a radiator and a feed for the DR. By optimizing the structure parameters, the hybrid structure allows not only the DR to resonate at one band with the broadside patterns but also the microstrip line to resonate at another band with the conical like patterns, and the two bands can be independently designed. Based on the above design concept, an antenna prototype suitable for wireless communication applications centered at 1.9 and 2.45 GHz was successfully designed, fabricated and tested.

Radiation from fast and slow traveling waves

This article presents an overview of the radiation from fast and slow traveling waves. The goal is to describe the mechanisms that give rise to the radiation in a leaky-wave antenna (LWA). An infinite aperture distribution and line-source assumptions will be used to convey the concepts. In addition, the relationship between the leaky-wave antenna and other types of traveling wave antennas will be elucidated.

Broadband cross-polarized bowtie antenna for breast cancer detection

Currently, various approaches to microwave breast cancer detection are being investigated by several research groups. Microwave approaches are expected to provide complementary information to that obtained with mammography, the gold standard method for breast imaging. Microwave images are related to the electrical properties of tissues, and there is some evidence to suggest that a contrast exists between normal healthy breast tissues and malignant tumors. In this paper, we investigate the frequency responses of tumors in a simple breast model using computer simulations over the frequency range of 2 to 4.25 GHz. Also, the influence of a variety of parameters (e.g. tumor shape, size, location and depth) on the frequency response is examined.

A linearized 1 GHz class E amplifier

An envelope elimination and restoration amplifier is analyzed, built and tested at 1 GHz. The predicted amplifier performance closely matches the measured amplifier performance. It is determined that a few key circuit parameters largely control the amplifier intermodulation performance. It is found that time delay matching of the phase signal information and the envelope signal information is very important. It is also found that the zero voltage signal feed through of the class E amplifier is also a significant parameter. The cascaded connection of the modulator and the class E amplifier, with respect to the power flow from the supply to the RF signal output places high demands on the modulator and amplifier efficiency.

Radar-based microwave imaging for breast cancer detection: tumor sensing with cross-polarized reflections

Microwave imaging for breast cancer detection is based on the difference in electrical properties of normal, fatty breast tissues and tumors. Tumors may be detected by observing variations in microwave signals transmitted through or reflected from the breast. Radar-based breast imaging methods use the reflected signals from the breast to form images, and generally this involves co-polarized reflections. Observation of the cross-polarized reflection was proposed in S.C. Hagness et al. (IEEE Transac. Ant. Propag., pp. 783-791, 1999), and it was shown that the cross-polarized response did not contain reflections from planar interfaces such as the chest wall. In this paper, we further explore the application of cross-polarization to tumor detection. A broadband antenna capable of detecting cross-polarized reflections is simulated, constructed, and measured. The feasibility of tumor detection with cross-polarized reflections is examined through simulations and experimentally.