TRANSMITTER COLLARS

General Information
Antenna Types
SMALLER ANIMAL COLLARS
EZ-FIT COLLARS
LARGER ANIMAL COLLARS

General Information
There is a great overlap in sizes between the types of collars described below. The selection of the appropriate collar depends on the type of study animal, on its habits, and on its environment. Except for the smallest collars, each of AVM's collars can be constructed using any transmitter type.

All collars are constructed with an on/off switch which is activated an external magnet.

Antenna Types:

Whip Antennas (exiting whips and internal whips)
Loop Antennas
Small Internal Coil only

Most radio collars radiate their signal through whip antennas. Very small collars often are constructed using loop antennas. Loop antennas can be less biasing to study animals and actually radiate stronger signal than whip antennas at the smaller sizes.

Loop antennas are electronically tuned to radiate their maximum signal at the exact neck circumference for which they are constructed. Loop collars designed for mammals have a maximum range of adjustment of about ±5% before the obtainable range begins to decrease due to the de-tuning of the loop antenna.

Fixed-size loop antennas have also become popular on several grouse and duck species.

If the study animal will not chew or pull the antenna off its collar or the collar of another animal, the more traditional whip antenna may be used;

SMALLER ANIMAL COLLARS

The CT Collar
The CT Collar is the only collar with no external antenna. The CT collar is a light-weight plastic collar with a self-locking mechanism. The SM1 Mouse-style or the SM1-H Mouse-style Transmitter and one small battery are fastened to the collar with a conformal coating of acrylic plastic. The tiny internal loop antenna of the Mouse-Style transmitter provides a ground-to-ground range of up to 200 meters using a hand-held Yagi antenna. This collar is commonly used on very small mammals, such as Microtus and Peromyscus spp. Animals smaller than Peromyscus are normally instrumented using glue-on's or peritoneal implants.

The CTW Collar
The CTW Collar is similar to the CT Collar except that instead of the SM1-Mouse style transmitter, a standard SM1 or SM1-H Transmitter is used, radiating its signal through a small exiting whip antenna. The antenna is fastened to the plastic collar up one side and exits from a position on the collar which will be behind the head of the animal, when the collar is being worn. The whip antenna can be made to exit from the collar either straight out or bent backwards at any specified angle.

The Rex-type CT or CTW Collar
A Rex-type Collar is a CT Collar or a CTW Collar built with one curved passageway through which a small electronic cable-tie can be passed, to serve as a field-replaceable collar for small animals. It can be used on many species for short-term applications and for applications where many transmitters will only remain on individual study animals for a few days and will then be recovered and placed on other individuals. It is especially popular for use in pesticides studies.

The BR Collar
The BR Collar is constructed from a thin strip of polyolefin-coated brass which is both the collar and the loop antenna. It requires neither fastener nor soldering to attach it to an animal in the field. It is adjusted to the correct neck size by a simple fold-back which is secured by a piece of heat-shrink tubing. Some researchers prefer to use very small metal mammal ear tags to secure the collar adjustment fold. The R Collar is normally constructed within the 5 to 12 cm neck circumference range. Typical animal size on which this collar is used is Glaucomys.

The BT Collar
BT Collars are sturdier than BR Collars. The collars are formed by passing a strip of polyolefin-coated brass through a vinyl-coated fiberglass tubing. Because of their light weight, Mini BT Collars, as pictured below, have no need for the additional tubing neck protector. The smooth edges of the tubing prevent neck chaffing by the brass strip, which is not only the structure of the collar, but also a tuned-loop antenna. The BT Collar can be made with any of the AVM transmitters. Attachment to the animal is done by selecting the proper closure hole on one end of the collar and slipping it over the mini-bolt attached to the other collar end, tightening a nut on a bolt and covering the site with heat-shrink tubing. BT collars are normally constructed in the 10 to 30 cm size range. Typical genus on which this collar is used is Mustela.

Our featured mini BT Collar is a tiny parrot collar.
Parrot: Aratinga canicularis Weight: 86 grams photo by Dr. Jack Bradbury, Cornell University	Mini BT Collar Weight: 3.9 grams
This collar has a neck circumference of 5 cm. It contains AVM's new G3-1V two-staged transmitter, powered by an Ag397 cell for a longevity of 2 to 4 months, depending on the output power needed. The collar shown has a tactile aversion coating and is shown with its attachment end untrimmed and unsealed.

The Perimeter Loop Antenna (BTPL) Collar
The Perimeter Loop Collar can be made with any type of collar material: coated brass, light weight machine belting, nylon belting or cable ties. This collar has no apparent external antenna. The transmitter's signal is radiated by a single, fine wire is built into the transmitter circuit and capacitively tuned up to radiate signal as a loop antenna. The loop runs around the perimeter of the transmitter/battery pod and is covered by the acrylic housing of the pod.

The loop antenna does not run around the study animal's neck, so there is no need to know exact neck circumferences as there is with BT Collars. Perimeter loop collars have now been successfully used on brush rabbits built like the description of CT Rex-style collars, described above, because neck sizes were unknown until the first individuals were trapped. They have also been used on parrots, configured like the BT Collars described above.

The BTW Collar
The BTW Collar is physically similar to the BT Collar. The brass structure of the loop of the BT Collar is still present, but in the BTW Collar the brass loop serves as the collar, but the antenna is a whip antenna exiting from the collar at the back of the neck. This collar is used when a whip antenna is preferred, but the larger MMW Collar is too heavy or too bulky to be used on a particular animal.

EZ-FIT COLLARS

The New, Revolutionary EZ-Fit Collar®
The EZ-Fit Collar is the most revolutionary and versatile radiotelemetry collar to come on the market in years! It’s elegant in its simplicity. It’s a transmitter/battery pod with an exiting whip antenna, attached to a collar segment that terminates with a ring on each end. Not only can any individual unit can be used on animals with a wide range of neck sizes, it can change from a fixed-size collar, to an expandable collar, to a drop-off collar, to a pet collar, at the user’s whim.

EZ-Fit For Felids

Lighter weight and more delicate than our EZ-Fit for Canids, these collars can be made in weights down to 10 grams.

Neck Size: 12 to 25 cm
Longevity: select from 6 months to 3 years, depending on weight and neck size

EZ-Fit For Canids

Chrome Rings allow insertion of your own collar or tying on with cord or elastic.

Neck Size: 20 cm and up
Longevity: up to 5 years, depending on weight and neck size

Here’s how it works: The pod is placed at the throat of the study animal and the collar strap is brought up the sides of the study animal’s neck. The ends of the strap are then connected with a material of the user’s choice, across the back of the animal’s neck, looping the material through the collar’s end rings and tying it off.

If the user intends to place the larger sizes of collars on a domestic dog, the dog's own collar can be run through the rings. The larger EZ-Fit Collars have a third chrome ring at their center that can be optionally used to keep the collar flush with a dog's collar, to prevent the EZ-Fit Collar from sagging.

By the researcher’s selection of the material used to attach the collar, the collar can become a drop-off collar, an easily removable collar, a pet collar...or just a collar that can be used over a very broad size range.

Table 2.1W The EZ-Fit Collar® Size Table.

Average Neck Size	Weights	Power Source	Longevities at Varying Power Outputs
Average Neck Size	Weights	Power Source	Long Life	Standard	High Power
12 to 24 cm	18 grams	1/2 AA	2 years	10 months	6 months
16 to 28 cm	26 grams	K-16	4 years	21 months	10 months
20 to 32 cm	35 grams	AA	7 years	28 months	1.1 year

A wide range of materials can be used to attach the collar, such as nylon cord, cotton ribbon, flat nylon braid, a piece of stainless steel minicable with a neck-protecting sheath or even a small nylon cat collar with a buckle.

The EZ-Fit Collar can be turned into a drop-off collar by selecting a connecting material that will eventually rot off, allowing the collar to drop from the animal.

The EZ-Fit Collar can be used as an expandable collar by using elastic running through a neck protector sheath for the connecting material.

The EZ-Fit Collar can even be attached to a pet collar that can be put on and taken off daily.

The ends of the connection material can be tied together, with the knots fastened with an adhesive such as cyanoacrylate glue or hot glue, or they can be held in place with heat shrink tubing. We could go on and on thinking up ways to use this new collar and materials to use to attach it, and we’re sure that you have some ideas of your own!

LARGER ANIMAL COLLARS

Collar Materials
AVM's Large animal collars are custom-designed for each individual project. We offer a wide range of collaring materials, from five-ply industrial machine belting to soft, woven nylon materials. The selection of collaring materials is generally made in our labs, based on our knowledge of the behavior of your study species and of the study area climate. If, however, your project has unusual requirements, we welcome you to help us select the collar material that will best suit your specific requirements. Otherwise, you can trust AVM to select the most appropriate material for your collars.

Pod Materials
The pod, or container housing the transmitting device and power source, may be constructed from conformally-poured acrylic, molded plastic or plated brass. The selection of the pod configuration and material is made in our labs, based on our knowledge of the behavior of your study species and on the likely ambient climatic conditions.

Mid-Sized Animal Collar Styles

The MMW Collar is similar to the LMW collar, but constructed from lighter-weight belting at smaller neck circumferences. Neck circumferences from about 25 to 40 are typical for MMW collars. Many of the smaller antelope and deer are typical study species instrumented with MMW collars.

Our featured MMW Collar is made for small deer. This particular MMW Collar is made for an animal with a neck circumference of 30 to 40 cm, but it can be made much smaller.
Weight: 85 grams
Collar Width: 2.2 cm
Longevity: 3 years

See the Medium Animal Collar Size Table for the full range of options for similar collars.

This is a pudu (Pudu puda),
the world's smallest deer.
Photo by Dr. Jaime Jimenez-Hott,
Universidad de los Lagos, Chile.

Table 2.2 The Medium Animal Collar Size Table for MMW Collars and D Collars

Average Neck Size	Weights*	Power Source	Longevities at Varying Power Outputs
Average Neck Size	Weights*	Power Source	Long Life	Standard	High Power
12 to 24 cm	30 grams	1/2 AA	2 years	10 months	6 months
16 to 28 cm	50 grams	K-16	4 years	21 months	10 months
20 to 32 cm	70 grams	AA	7 years	28 months	1.1 year
32+	100 grams+	C	N/A	5.4 years	2.7 years

*weights are approximate and will vary depending on the neck size, the antenna gauge and weight, and on other elective parameters

When a collar the size of the MMW collar is needed, but an exiting whip antenna cannot be tolerated, as described in the section above, describing LM Collars, there are two choices for collar styles, the D Collar and the MM Collar. In this size range, loop collars, although difficult to tune and often difficult to write specifications for, are used because they radiate stronger signals than do collars designed using enclosed whips.

The D Collar radiates its signal though a loop antenna. The D Collar is typically applied to animals such as the larger foxes, raccoons, hares and smaller felids. Although the normal size range for D Collars is about 25 to 40 cm, very miniaturized D Collars (16 to 25 cm) can also be constructed for use on particularly aggressive small primates who might tear BT Collars apart. Because the loop antenna completely encircles the neck of the animal, good neck measurements must be provided because adjustments of more than about +5% will diminish the signal strength of the transmitter. It will continue to transmit as it is adjusted as far as +10% from its intended circumference, however, the range of reception will decrease.

Our Featured D Collar is The Remarkable Raccoon Collar.

Weight: 70 grams
Collar Width: 2 cm
Longevity: select from 18 to 28 months

The MM Collar is a miniaturized, lightweight version of the LM collar. Its size range overlaps with the upper portion of the D Collar's and the lower part of the LM Collar's and is used as a light-weight LM collar or used when the researcher does not wish to cope with the asymmetry of signal radiation of the loop collar. It is also often used in place of the D Collar when there is no before-hand access to neck measurements accurate to +5-10% of total circumference of the study species. Rather than make a guess and miss by more than 10%, the weaker signal produced by a short-whip, small MM collar may be preferred to a detuned D Collar.

Large Animal Collar Styles

The LMW Collar is the most widely used of the Large Animal Collars. LMW Collars are constructed from 3-ply, 30 to 65 mm-wide industrial machine belting. The belting is normally made of a synthetic fabric impregnated with neoprene or some other flexible and resistant plastic. The -W suffix in the name signifies that the collar's transmitter has an externally-exiting whip antenna which exits top of the collar behind the head of the animal on which the collar is placed. LMW Collars can range in circumference from about 40 to 85 cm and were originally designed for most ungulates, such as deer, goats, sheep and bovids, in other words, most large hoofed animals.

The Inverse LMW Collar places the pod at the back of the neck of the animal, with a 30 cm whip exiting from the middle of the pod, angled back a bit toward the tail of the animal. The Inverse LMW Collar can only be applied to an animal that is very flat at the back of its neck (like many crocodilians) or has such a pronounced ridge at the back of its neck (like a feral hog) that the collar will be prevented from rotating, causing the antenna to end up exiting under the chin of the animal. If the animal is large enough, a counterweight can prevent the rotation (see the description of the Inverse LMX Collar, below.) The use of inverse collars is uncommon, but effective in the production of greater range under unusual circumstances.

The LM Collar is similar to the LMW collar in all aspects, with the exception of the fact that its whip antenna remains internalized within the collar sewn between two layers of collar belting. Large animals that could pull an antenna out of a collar must be instrumented with LM Collars. Typical candidates for LM collars are bears, wolves and a few of the more destructive ungulates, such as elk. Most of the large cats, such as lions and tigers are collared with LM collars. The operant rule is that if an exiting whip can be used, it should be used, because an exiting whip antenna produces greater range than a non-exiting whip. But if an animal will destroy an exiting whip, an internal whip should be used, because an internal whip will produce more range than no whip at all, which is what you would have after your study animal ripped out its whip.

The Standard and Inverse LMX Collars are similar to LMW Collars, but designed for animals with neck circumferences larger than about 85 cm. When a collar reaches this size, if its antenna originates from an under-the-chin pod, the distal end of the antenna will never reach the point where it is to exit the collar at the back of the neck and its signal radiation will be greatly reduced. Hence, either a special 1/2 wavelength antenna must be installed or an Inverse Collar must be constructed. The Standard LMX Collar uses a 1/2 wave antenna, while the Inverse LMX collar, similar to the Inverse LMW collar, places the pod at the back of the neck of the animal, with a 30 cm whip exiting from the middle of the pod, angled back a bit toward the tail of the animal. The base of the antenna is reinforced with a heavy-duty extension spring to prevent breakage. The inverse collar is counter-weighted under the chin of the animal so that the antenna will always remain pointing up. A large male moose is a typical study animal for a Standard LMX Collar, while elephants and rhinos are typical study animals for the Inverse LMX Collars.

Collar Options for Larger Animals

AVM offers the following options:

Expandable Collars:

Type A: is made to expand and stay on the animal at the adult, expanded size.
Type B: will expand to the point where the expansion component is exposed to environmental factors so that it will eventually decompose and fall off.

(See the section on Transmitter Modules for a description and picture of AVM's Ungulate Ear Tags as an alternative to expandable collars.)

Drop-off Collars
Most collars can be fitted with a drop-off feature. A patch of sturdy cotton canvas is sewn into the collar. The patch will eventually degrade due from exposure to UV, water, temperature stress, etc.