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The Ohio Hydroponic Crop Research and Extension Program (OHCP) is a multifaceted program integrating applied research and outreach efforts to assist hydroponic vegetable and specialty crop producers in Ohio. The OHCP provides technical, cultural, and marketing support to sustain small and medium-sized producers who conduct business in an increasingly competitive marketplace. Research and extension efforts are aimed at developing tools that maximize crop growth and harvestable yield of high-value, locally-grown hydroponic crops. Tools developed through the OHCP allow producers to make informed decisions that affect the long term viability of their business. Several recently developed tools include a water quality assessment package to assess and improve water management and fertilization practices in hydroponic facilities, a series of comparative diagnostic tools for determining nutrient imbalances in hydroponic lettuce production, and an instrumentation package of environmental sensors to assess greenhouse environmental conditions and their impact on crop growth and yield. Key outreach efforts of the OHCP include consultations and site visits, a monthly greenhouse newsletter, an interactive hydroponic website (www.oardc.ohio-state.edu/hydroponics/), as well as the development of fact sheets and educational bulletins. Additional efforts include the development of a demonstration greenhouse designed to illustrate various hydroponic production techniques, compare yield of commercially available crops and alternative crops for prospective and existing hydroponic producers.

If decisions are to be made concerning when and how much to irrigate container-grown plants, then procedures for measuring the accuracy and reliability of Volumetric Water Content (VWC) sensors should be developed. Three statistical properties were used to characterize the quality of VWC sensor data for this study: (1) bias, (2) variance, and (3) measurement system discrimination. The objectives of the tests reported here were to evaluate the measurement capability of three commercially available moisture sensors. Based on standardized repeatability and reproducibility measurement procedures for determining variance, estimated standard deviation (measurement error) for the WET Sensor was 2.11% VWC while the HydroSense and the ThetaProbe were 1.21% and 1.43%, respectively. Bias readings for all three instruments were 3% to 5% below a 30% reference value. Evaluation of discrimination in terms of measurement system acceptance calculations found all three sensors were well within a 10% to 30% guideline that compares measurement error to the range of expected values to be discriminated.

The application of new dielectric materials with μ, ϵ, and low loss to antennas is investigated. A zero-order analysis reveals the advantages and limitations of these materials for patch antennas. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26, 75–78, 2000.

The capability to monitor and control moisture tension in container-grown plants could be enhanced considerably if precise, reliable measurements could be made in the plant root zone. Tensiometers and appropriate computer software and hardware have been used with some success in research applications to schedule irrigation. This research focused on the idea of extending the use of tensiometers from laboratory investigations to greenhouse growing applications using a system available commercially. A Q-COM computer-control system along with tensiometers were used to monitor and control moisture tension for potted mini-roses (Rosa hybrida ‘Meidanclar’ and ‘Meirutral’) for the research reported herein. Control capability for low tension (3 to 6 kPa), medium tension (7 to 10 kPa, 9 to 12 kPa), and high tension (15 to 18 kPa) treatments were compared under winter conditions using 10 cm pots, summer conditions using 15 cm pots, and autumn conditions using 15 cm pots. All experiments were run in a greenhouse with plants randomly placed on standard benches. The results indicated controlling tension within preset limits was more successfully achieved under low-radiation, wintertime conditions (in a northern Ohio climate) than under either a summer or an autumn environment, particularly for tensions above 12 kPa. Reliable, stable control of moisture tension within 3 to 6 kPa was achieved all three times of the year. Growers could expect to be successful at controlling low tensions (3 to 6 kPa) with this system. At higher tensions, the reliability of the system decreases substantially.

This study was preliminary to developing feed-forward computer control algorithms to irrigate Acer Rubrum (Red Maple) trees in proportion to predicted transpiration. Transpiration rates of Acer Rubrum and related climate variables were measured continuously in a very high evaporative demand greenhouse environment and compared independently to solar radiation and vapor pressure deficit (VPD). Measured transpiration rates were further compared to predicted transpiration based on the combination equation. Based on regression analyses and the coefficient of determination (R 2 ), the single variable VPD predicted transpiration equally as well as the combination model with an R squared value for both equal to 0.861. Meanwhile, using the single variable solar radiation to predict transpiration resulted in an R squared value of 0.652.

An anechoic chamber used for missile test or simulation inherently adds boresite error, generally as a result of sidewall reflections. A simple method of analysis shows this error depends on the sidewall angle of arrival through the antenna difference pattern and the bistatic reflection coefficient of the sidewall material. This material coefficient which is seldom measured is of critical importance.

The Bode limit on bandwidth enhancement through use of an ideal impedance matching network does not allow changes in antenna reflection coefficient over the bandwidth. An exact correction factor is derived from the Fano limitations, yielding a simple modification to the Bode limit. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 875–877, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23244

Analytic expressions which show the interdependence between biological and physical factors for aerobic composting are presented. In particular, equations for pressure drops through piping and compost are integrated into the analytic models. Effects of operating temperature, bed depth, compost rate of degradability and compost maturity on operating cost were evaluated using the models. Equations for determining optimum bed depth for composting under conditions of variable bed depth and fixed bed depth are presented.

Designs of full-scale composting systems have often been made on limited data obtained from totally different waste materials. For example, studies from the late 1950s for ground garbage and the late 1970s for sludge woodchip mixes are often cited as the source of data for determining aeration requirements. This article summarizes kinetic data from 38 pilot studies on municipal solid waste (MSW), biosolids, food waste, poultry manure and separated dairy waste and describes how to evaluate the kinetic parameters of composting from the experimental data. The evaluated parameters were then used to calculate airflow requirements, time fan can be off, and time to first remix for water addition.

Oscillations in scan impedance over a finite array have been shown previously; here they are modeled by a Gibbs-type standing wave. The wave period derived from the transform of a single pulse with phase shift is .5λ/(1 − sin θ0), which closely fits simulated array data. Gibbsian models containing sine integrals provide fair to excellent matches to computer-simulated dipole arrays, with and without screen, and for E and H plane scans. The E plane scan results are new, as are those for the H plane scan with screen.

Three mixtures of ground yard trimmings (50 percent by volume in each mix), chicken manure (50, 27 and 40 percent) and potato processing, gelatin and bakery wastes were composted in four pilot-scale, 208 liter, insulated vessels (the first mixture was replicated). The mixes were obtained from a commercial composter and were studied both to obtain kinetic parameters for materials of this type and to help solve a problem of inconsistent maturity of product at the commercial operation. A 65°C set point controlled a high/low fan aeration system for each vessel. Temperature (at several points), air flow, oxygen consumption, carbon dioxide evolution and ammonia production were monitored. The vessels were weighed and materials were remixed twice each week during a four week composting period. At each remix, water was added to maintain a 50 percent by weight moisture content, and samples were taken for moisture content, volatile solids, chemical composition (including C:N ratio), pH and compost stability determin...

Equations for scheduling remixing and water additions required at remix to maintain specific moisture levels during composting were developed. Analyses of compost systems for various levels of compost mixes and operational temperatures were completed. Results indicated a weekly (or more often) mix schedule was needed during the period of composting when mixes had decomposition rates greater than 0.05 kg/kgco.day. Use of inert bulking agents decreased the number of remixes required and increased time between mixing.

Over 1,000 questionnaires were sent to a randomly selected sample of Ohio grain producers. The survey focused on marketing, feeding, and drying practices for shelled corn. The respondents reported six out of seven metric tons (bushels) of shelled corn produced in 1992 were marketed commercially; nearly all of the remainder were fed to livestock. Approximately four out of five metric tons (bushels) were dried on the farm. A high-temperature dryer with in-bin cooling was used for 42% of shelled corn dried on the farm; natural air was used for about 2%.

Scan impedance of elements, especially near the edge of a finite array, differs from that of an element in an infinite array. A numerical experiment shows the standing-wave behavior of scan impedance over the finite array, for a range of scan angles. The standing wave exists even for a broadside beam. © 1995 John Wiley & Sons. Inc.

Of the many contributions Wheeler made to phased arrays, five of the most important will be briefly discussed. Waveguide Simulator 1948 Current Sheet 1965 Ideal Element Pattern 1965 Grating Lobe Series and Impedance Crater 1966 WAIM 1968

A natural product known as taxol has been approved by the FDA for treatment of ovarian and breast cancers. In addition, preliminary clinical studies have shown encouraging results when using taxol to treat melanomas, lung, head, and neck cancers. Ornamental yews have been identified as a potential renewable source of taxol and related taxanes. Commercial nurseries were surveyed during Summer and Fall 1991 as a basis for estimating populations of Taxus cultivars currently growing in the United States. Clippings of selected cultivars were sampled from nursery fields in Ohio and Michigan to estimate expected clippings yields as a function of cultivar and cultivar age. More than 30 million Taxus plants were reported to be grown by the 19 major nurseries that responded to the survey. About 88% of all Taxus plants reported in the survey were grown in the three-state area of Ohio, Michigan, and Pennsylvania. Taxus × media `Densiformis', `Hicksii', and `Brownii' were found to be grown by nearly all nurseries in the survey; more than half grew T. × media `Wardii' and T. cuspidata `Capitata', while other well-known cultivars seem to have been specialties of one or two nurseries. Annual clippings yields on a dry-weight basis (db) ranged from ≈20 g/plant to 140 g/plant. Expected yields were found to be very dependent upon plant age and cultivar. Taxus × media `Hicksii' appeared to be the most ideal ornamental yew that could provide a renewable source of taxol because of immediate availability and potential for mechanical harvesting of upright clippings. An estimated 3000 to 4000 ovarian cancer patients could be treated annually with the taxol currently available for extraction from T. × media `Hicksii' clippings.

Spent wood fiber pallets bonded with urea-formaldehyde were composted in 200L pilot vessels. Dry matter loss over 14 days was 5.6 percent for the wood-UF with 1 percent urea added. Off-gas from aeration was sampled for emitted ammonia and formaldehyde. No formaldehyde emissions were detected during composting of unamended or urea amended materials. Formaldehyde emission was

The use of leaf amendment in woodchips/sludge composting was studied in pilot-scale and full-scale operations. Use of leaves at a rate of 20 percent by volume was compatible with present practices and equipment at the Columbus Compost Facility, but higher rates caused materials handling and curing problems and would necessitate system modifications. Only very slight reduction in new woodchip usage was observed for the 20 percent leaf amendment, but output of sieved-finished compost was doubled. Leaf usage increased airflow requirement per unit dry matter during the initial stage of composting but decreased ammonia release throughout the composting process. On the other hand, use of recycled materials, compost and sieved woodchips, increased ammonia release. Adequate moisture and periodic turning in the pilot-scale studies enhanced composting for all treatments. Leaf usage may necessitate forced aeration during curing to keep full size piles aerobic. In addition, leaf usage increased the total materials ha...

An accurate representation of circular aperture near fields, including those in the projected aperture region, is obtained through a modification of the geometrical theory of diffraction launching coefficient.

A new kinetic concept was applied to the yard waste composting process. Yard waste mixtures with different fractions of grass clippings were composted in pilot-scale vessels. Ammonia emissions were highest with high fractions of grass clippings. Calculation of reaction rate constants was based on heat and materials balances. Although the compost mass ratios (a dimensionless number that describes how far the process has advanced) of the mixtures after composting were similar, their chemical and biological analyses reveal differences. A first order reaction model is presented that can be used for plant design. The effects of temperature and particle size on process kinetics need to be investigated further.

A promising cancer chemotherapeutic agent, taxol, is currently scheduled for full clinical development by the National Cancer Institute. The ornamental yew, Taxus x media ‘Hicksii’, has been identified as a renewable source of taxol. However, clippings from the plant must be properly and efficiently harvested, dried, and stored. Thin-layer drying studies of Taxus clippings, needles, and stems were conducted. Parameters for the thin-layer drying equation were successfully determined for drying temperatures of 30, 40, 50, and 60° C. The results showed that drying rates increased 28-, 15-, and 3-fold as drying temperatures increased from 30°, 40°, and 50° C to 60° C, respectively. Also, stems dried at a faster rate than needles and needles dried at a faster rate than whole clippings. Taxol yields (g/100 g, d.b.) from stems were nearly constant for the four temperatures tested. However, yields from needles increased linearly as drying temperatures increased from 30 to 60° C. The highest taxol yields were obtained from clippings. Nearly constant yields were obtained (~ 0.014 g/100 g, d.b.) for drying temperatures of 40, 50, and 60° C. The lowest yields for all three plant components occurred when the drying temperature was set at 30° C. The results suggest 60° C is the best temperature set point for drying Taxus x media ‘Hicksii’, but temperatures higher than 60° C should be evaluated.

The resonant CWTHA is examined via a moment-method simulation. The results show a very high impedance at first resonance with a narrow bandwidth and low efficiency. At second resonance, the resistance is less than an ohm, the reactance is zero, and again, the bandwidth is narrow. The azimuth patterns are not omnidirectional, but may have a dip of 10 dB or more. The simulation shows a loop-mode cancellation of at least 140 dB. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 408–410, 2001.

The calculation of near-field fluences of high-power microwave (HPM) antennas is reviewed. Near-fields close to large square or circular antennas are calculated rapidly using the geometric theory of diffraction; one specular and two edge-diffracted rays are used. In the principal planes, accuracy is roughly 2 dB at the -40-dB level, for both uniform and tapered excitations. A universal power density curve is obtained along a line parallel to the aperture, when the distance to the line is normalized by 2D/sup 2// lambda , and the transverse distance is normalized by D (where lambda is the radiation wavelength and D is the aperture width). Diagonal plane fields are calculated using equivalent edge currents via a single numerical integration. Fluence envelopes are obtained in the sidelobe region simply by summing the magnitudes of the two edge rays. >

Hydroponic growing systems (HGS) consist of ideal technology for producing fruits and vegetables that are to be marketed locally. However, there is a difference between a working system and one that is commercially successful. Most HGS are not easy to manage by the inexperienced and the unskilled. Research reports verify the potential for lettuce to be produced both successfully and unsuccessfully. Therefore, many benefits can potentially accrue from continued research efforts to refine inputs to HGS while identifying the risks of improper operation and errant decision making. This paper describes a Hydroponic Lettuce Research Laboratory that was recently constructed at the Ohio Agricultural and Research Development Center (OARDC) in Wooster, Ohio. The water and nutrient delivery system is capable of randomly and simultaneously delivering 16 different treatments to lettuce crops via 16 growing channels supplied by eight recirculation tanks. Specified combinations of growing media, cultivar, solution flow rate, pH, EC and solution temperature were studied during two experiments. A disappointing result was the magnitude of the “within treatment” variation. The overall average mass for lettuce grown during the autumn 2008 experiment was 119.0 grams (wb) per head compared to 161.6 for spring 2009. This increase was attributed to the installation of pH control capability prior to the second experiment.

A closed form near-field power density envelope is derived from the geometrical theory of diffraction formulation. The envelopes exist on lines parallel to the aperture in principal planes. These results, and those from an equivalent edge current integral, are compared with numerically integrated results.

Response to thermal cycling of a 0/90 cross-plied P100 Gr-6061 aluminium composite laminate was studied between a minimum temperature (T min) of 25 ‡C and maximum temperatures (T max) of 100 and 540 ‡C. Strain hysteresis was observed between the heating and cooling half-cycles and was attributed to anelastic strains induced by matrix residual stresses. A residual plastic strain was also observed after the first cycle, and was seen to disappear after subsequent cycles. Alteration of the thermal residual stress state of the matrix via heat treatments was found to change significantly the magnitude of the plastic strain. These results were compared with those of studies on unidirectionally reinforced P100 Gr-6061 aluminium composites, and the differences were explained on the basis of the residual stresses resident in the matrix. Optical and electron microscopy were also utilized to observe thermal damage, which occurred predominantly along improperly bonded fibre-matrix interfaces.

Use of natural air to dry shelled corn, soybeans and specialty crops offers an unusual opportunity for growers to participate in the green revolution and reduce the use of fossil fuels. Energy required and associated costs for natural-air grain drying (NAGD) are approximately one-third of that typically used for high temperature drying. The process minimizes or avoids the use of propane (which has tripled in price from $0.75 to $2.25/gal in two years) while depending on free energy that is available from natural air. Modern electronic controller technology can be used to control the NAGD process in bins and monitor the condition of grain in storage while avoiding wasteful overdrying. Earlier average planting dates along with high yielding full-season hybrids with fast dry down capability have lead to lower shelled corn moisture contents at harvest time thus enhancing prospects for NAGD to work successfully. Existing storage bins can be effectively equipped for natural-air grain drying for $1.00/bu or less if the bin already has a perforated floor, sump and unloading augers installed. Ethanol plants typically store no more than 15 to 30 days of their production capacity. This implies on-farm storage capacity will have to expand. Maintenance of high quality corn for ethanol production through hot summer months will remain critical since pricing will continue to be based on No. 2 corn. Significant savings can be realized when 18% MC corn is harvested and stored over winter for animal feed without drying. Whether corn is stored for export, ethanol or stored and fed to animals, benefits will accrue for growers who take advantage of NAGD and associated electronic controller technology.

The short-circuit, match, and antenna components of RCS are examined for a thin-wire dipole over a range of lengths and incidence angles. Resonances are identified and discussed in terms of current distributions and antenna patterns. The antenna component contains more resonant peaks than the short-circuit component due to differences in current distribution. The results are useful for RCS understanding and control.

A mathematical model of a closed-loop feedback control system for controlling microirrigation of container-grown nursery plants was developed and tested. Moisture tension in the container medium was the control variable. The system's characteristic transfer function parameters included a time delay (infiltration time), on-off control (irrigation pump), pumping rate, mass of potting medium, moisture tension as a function of potting medium moisture, and a tensiometer response function. Calibration and validation of the model was done using experimental data collected for Red Sunset red maple (Acer rubrum 'Red Sunset') during late summer of 1997. A time-varying, vapor pressure deficit/evapotranspiration transfer function, ETVPD, was used to estimate the plant's rate of removal of water from the root medium (R-2 = 0.684). The transfer function underestimated total irrigation water by 25% and overestimated irrigation frequency by 37.5% (11 vs. 8 cycles) during the 14-day experimental validation period. Major differences between experimental validation and simulated results were attributed to the accuracy of the ETVPD model and the use of zero infiltration time (tau(DT)). Key factors identified as directly affecting stability and accuracy of tensiometer-controlled irrigation, in addition to the identified system's parameters, were size of the plant root system and placement of the tensiometer(s). Results showed that only 18% of the total soil medium mass was affecting the systems response function based on the experimental setup of one tensiometer in the potting medium.

[1] A planar array of dipoles, with contiguous collinear dipole ends connected by a fixed inductor or capacitor, is evaluated. A Moment Method simulation of a 20 × 20 array provides Scan Element Pattern (gain per element), Scan Impedance, and current distributions. Cases considered, over a 10:1 bandwidth (dipole length .05λ to .5λ), include zero impedance coupling, capacitor coupling, inductor coupling, and Non-Foster negative inductor coupling. The last is outstanding, probably because the physics of the Non-Foster coupling makes sense.

The development of an irrigation control system that used plant-response based feedback is presented. The crop water stress index (CWSI-IRT) based on infrared canopy temperature measurement was employed as the feedback parameter. The aspects of the control system that were developed included the design of a data acquisition and control system for the greenhouse where experiments took place, the selection of a CWSI-IRT method appropriate for the greenhouse setting, and the determination of response time for the feedback variable (CWSI-IRT) to input of water into the system. A distributed I/O data acquisition (DAQ) and control system was established in a small research greenhouse at OARDC, Wooster, Ohio. Four CWSI methods were investigated using available growth chamber data (Kacira, 2000), and experiments in the research greenhouse. Results of the CWSI selection testing showed some disparity between the CWSI-IRT measurements and weight based CWSI (CWSI-wt) used as the baseline. In growth chamber experiments, the correlation was r2 = 0.69 (Kacira et al., 2002). However, greenhouse experiments showed correlations were r2=0.47. Low correlations were thought to be due to noise of the measured ET used to calculate CWSI-wt, as well as variability of temperature and light conditions in the greenhouse contributing to CWSI-IRT variations. Analysis is presented of the variability of time series greenhouse data and the subsequent effects on modeled CWSI-IRT results. The response time for canopy temperature with water input determined the delay in plants’ response to irrigation events. Investigations using a growth chamber set-up showed an average total time of 122 minutes to reach 95% of the final canopy temperature. This corresponded well to previous measurements in Kacira (2000). The DAQ and control system, the CWSI-IRT method selection and canopy temperature response time information were then integrated into a closed loop CWSI feedback proportional control system. It was evaluated for use as a plant water status management tool to maintain low plant stress, while reducing runoff and waste.

The pattern of a circular aperture with errors normally requires a double numerical integration. When the aperture function is rotationally symmetric or with sin θ variation, the double integration can be reduced to a single integration of a Struve function; these are readily calculable. Thus the pattern calculation is greatly simplified. © 1995 John Wiley & Sons, Inc.

The results of a series of four clinical studies demonstrated that disposable baby wipes were milder to the skin than use of a cotton washcloth and water, recognized as a "gold standard" for skin mildness. Importantly, the baby wipes caused no significant change from the baseline value in any of the skin parameters examined. This observation verified that the test wipes are minimally disruptive to the epidermal barrier and thus suitable for use on intact or compromised, irritated skin.

Advances in evapotranspiration modeling have led to a variety of formulas and terms used in irrigation control research. Four models that represent the progression from outdoor, “big leaf” estimates to indoor, greenhouse–specific formulations are compared in this article. Each of the models was algebraically reduced to common and consistent terms. The data from a lysimeter study were used to compare evapotranspiration combination models using evapotranspiration (ET) rates of a ‘Red Sunset’ Red Maple tree (Acer rubrum ‘Red Sunset’) grown in a controlled–environment greenhouse. The measured ET was compared with two empirical climatic factors (solar irradiance and vapor pressure deficit) and with calculated ET based on four evapotranspiration models: (1) Penman, (2) Penman–Monteith, (3) Stanghellini, and (4) Fynn. A measure of the model performance is given by the Nash–Sutcliffe R2, or model efficiency. The relationship between measured and calculated ET for the Stanghellini model was calculated to have a model efficiency of R2 = 0.872, while the other models yielded correlations of R2 = 0.214, R2 = 0.481, R2 = –0.848 for Penman, Penman–Monteith, and Fynn, respectively. The differences between the models are discussed, revealing the importance of the leaf area index factor and a sub–model for irradiance in the plant canopy. Based on the coefficient of determination, vapor pressure deficit alone yielded a good linear correlation to measured ET (r2 = 0.884), while solar irradiance alone resulted in r2 = 0.652.

A lysimeter study was conducted to evaluate evapotranspiration combination models using evapotranspiration (ET) rates of Red Sunset red maple (Acer Rubrum ‘Red Sunset’) trees grown in a controlled-environment greenhouse. The measured ET was compared with two empirical climatic factors, solar irradiance and vapor pressure deficit, and with calculated ET based on four evapotranspiration models, Penman, Penman-Monteith, Stanghellini and Fynn. Each of the models was algebraically reduced to common and consistent terms. The relationship between measured and calculated ET was best using the Stanghellini model (correlation coefficient (r) = 0.958, root mean square error (RMSE) = 0.006, average absolute error (AAE) = 0.004), while the others yielded correlations of r = 0.940, r = 0.886, r = 0.872 for Fynn, Penman-Monteith, and Penman, respectively. Vapor pressure deficit alone yielded a good correlation to measured ET (r = 0.940), while solar irradiance had r = 0.807.

Small endfire arrays of isotropes with uniform amplitude and progressive phase are examined. The directivity is maximized, and the increased phase and directivity values are given for N = 2–20.

The onset of argyria following the use of dietary supplements containing colloidal silver protein is presented. The patient was using a silver-containing product for cold and allergy prophylaxis. We review the past and present medicinal roles of silver and include a differential diagnosis for argyria. The hyperpigmentation of argyria is usually permanent, and it follows a sun-exposed distribution. This case report highlights the potential for toxicity following the use of dietary supplements and demonstrates the importance of physician inquiry regarding alternative medicines. Finally, we examine the limited role of the Food and Drug Administration (FDA) in regulating alternative medicines marketed as dietary supplements.

Cutaneous manifestations, potential sources of major discomfort, anxiety, and concern often coexist with or precede symptoms of systemic features of rheumatic diseases in children and adolescents. This chapter identifies skin features that may indicate rheumatologic disorders and describes various treatments and management approaches for cutaneous features.

The relation of Q and half-power bandwidth for antennas, Q = 1/BW, is well known. Here it is shown that 1/Q gives an accurate bandwidth for electrically small dipoles and loops. Bandwidths from 1/Q are compared with exact bandwidths, using a sinusoidal current computer model for dipoles, and a constant current model for loops. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1170–1171, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22373