Abstract
The optimal antenna of transmitters used in small aquatic animals is often a compromise between efficient radio wave propagation and effects on animal behavior. Radio transmission efficiency generally increases with diameter and length of the conductor, but increased antenna length or weight can adversely affect animal behavior. We evaluated the effects of changing antenna length and material on the subsequent tag output power, reception, and detection of tagged fish. In a laboratory, we compared the relative signal strengths in water of 150 MHz transmitters over a range of antenna lengths (from 6 to 30 cm) and materials (one weighing about half of the other). The peak relative signal strengths were at 20 and 22 cm, which are approximately one wavelength underwater at the test frequency. The peak relative signal strengths at these lengths were approximately 50% greater than those of 30 cm antennas, a length commonly used in fisheries research. Few significant differences were present in distances for the operator to hear or the telemetry receiver to decode transmitters from a boat-mounted receiving system based on antenna length, but the percent of tagged fish detected passing a hydroelectric dam fitted with an array of receiving systems was significantly greater at the antenna length with peak output power in laboratory tests. This study indicates careful choice of antenna length and material of small transmitters can be used to reduce weight and possible antenna effects on animal behavior, to maximize tag output power and detection, or to balance these factors based on the needs of the application.
References
Adams, N. A., D. W. Rondorf, S. D. Evans, J. E. Kelly & R. W. Perry, 1998. Effects of surgically and gastrically implanted radio tags on swimming performance and predator avoidance of juvenile Chinook salmon (Oncorhynchus tshawytscha). Canadian Journal of Fisheries and Aquatic Science 55: 781–787.
Allison, P. D., 1999. Logistic Regression using the SAS System: Theory and Application. SAS Institute Inc, Cary, North Carolina, USA.
Anglea, S. M., D. R. Geist, R. S. Brown & K. A. Deters, 2004. Effects of acoustic tags on swimming performance and predator avoidance of juvenile Chinook salmon. North American Journal of Fisheries Management 24: 162–170.
Beeman, J. W., P. V. Haner & A. G. Maule, 1998. Evaluation of a new miniature pressure-sensitive radio transmitter. North American Journal of Fisheries Management 8: 458–464.
Beeman, J. W., C. Grant & P. V. Haner, 2004. Comparison of three underwater antennas for use in radio telemetry. North American Journal of Fisheries Management 24: 275–281.
Cheek, T. E., M. J. Van den Avyle & C. C. Coutant, 1985. Influences of water quality in distribution of striped bass in a Tennessee River impoundment. Transactions of the American Fisheries Society 114: 67–76.
Cooke, S. J. & C. M. Bunt, 2001. Assessment of internal and external antenna configurations of radio tags implanted in smallmouth bass. North American Journal of Fisheries Management 21: 236–241.
DeMaw, D., 1987. W1FB’s Antenna Notebook. The American Radio Relay League, Newington, Connecticut, USA.
Guy, C., H. Blankenship & L. Nielsen, 1996. Tagging and marking. In Murphy, B. W. & D. W. Willis (eds), Fisheries Techniques, 2nd edn. American Fisheries Society, Bethesda, Maryland, USA, 353–384.
Johnson, G. E., N. A. Adams, R. L. Johnson, D. W. Rondorf, D. D. Dauble & T. L. Barila, 2000. Evaluation of the prototype surface bypass for salmonid smolts in spring 1996 and 1997 at Lower Granite Dam on the Snake River, Washington. Transactions of the American Fisheries Society 129: 381–397.
Littell, R. C., G. A. Milliken, W. W. Stroup & R. D. Wolfinger, 1996. SAS System for Mixed Models. SAS Institute Inc., Cary, North Carolina, USA.
Martinelli, T. L. & R. S. Shively, 1997. Seasonal distribution, movements and habitat associations of northern squawfish in two lower Columbia River reservoirs. Regulated Rivers: Research and Management 13: 543–556.
Martinelli, T. L., H. C. Hansel & R. S. Shively, 1998. Growth and physiological responses to surgical and gastric radio tag implantation techniques in subyearling Chinook salmon (Oncorhynchus tshawytscha). Hydrobiologia 371/372: 79–87.
Moser, M. L., A. L. Matter, L. C. Stuehrenberg & T. C. Bjorn, 2002. Use of an extensive radio receiver network to document Pacific lamprey (Lampetra tridentata) entrance efficiency at fishways in the Lower Columbia River, USA. Hydrobiologia 483: 45–53.
Stokes, M. E., C. S. Davis & G. G. Koch, 2000. Categorical Data Analysis Using the SAS System, 2nd edn. SAS Institute Inc, Cary, North Carolina, USA.
Winter, J., 1996. Advances in underwater biotelemetry. In Murphy, B. W. & D. W. Willis, (eds), Fisheries Techniques, 2nd edn. American Fisheries Society, Bethesda, Maryland, USA, 550–590.
Acknowledgements
We thank our colleagues at the US Geological Survey and at Lotek Wireless for their assistance in this research, and the staff of the Pacific States Marine Fisheries Commission at John Day Dam for providing test fish. The manuscript was improved by insightful comments of two anonymous reviewers. This work was funded in part by the Portland District of the US Army Corps of Engineers, contract W66QKZ51376463.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Beeman, J.W., Bower, N., Juhnke, S. et al. Effects of antenna length and material on output power and detection of miniature radio transmitters. Hydrobiologia 582, 221–229 (2007). https://doi.org/10.1007/s10750-006-0543-z
Issue Date:
DOI: https://doi.org/10.1007/s10750-006-0543-z