4.5" Telescopic Antenna
The Telescopic Antenna can be used for either receiving or transmitting. It can be used as a receiving antenna from 25 MHz through the 1296 MHz Ham Band, and it can also be used as a 1/4 wavelength transmitting antenna from 130 MHz through 535MHz. For transmitting, the antenna length must be set as close as possible to the transmitting frequency’s 1/4 wavelength. This ensures the best possible transmission by using the proper standing wave ratio (SWR).
The antennas receiving and radiating element such as arms, dipoles are made up of extensible system of metal tube of approximately equal length and are concentric.
Such design facilitates the change in length of the antenna elements during tuning and permits the size of the antenna to be reduced when it is not in operation.
Below is a brief explanation of the design :
1. Such property makes the telescopic antenna very versatile and handy while doing certain things like transport or storage.
2. The tubes fit into one another with some friction.
3. For each pair of telescoping tubes, the interior diameter of the outer tube is approximately equal to
the exterior diameter of the inner tube.
4. The friction is needed to provide electrical contact and to maintain the required length of each
element of the telescopic antenna under operating conditions that is, under the action of gravity
or exposure to shaking or vibration
5. In some cases the required position of the tubes may be fixed by additional means.
For example, collets chucks or springs may be employed.
1. Can work perfectly under the action of Gravity or exposure to shaking and vibration
2. The length of the antenna can be fixed.
3. Body is made of anti - corrosive material for long life time.
Telescopic antennas are used principally in
1. Conjunction with radio receivers, radio transmitter-receivers,
2. Portable television receivers, and
3. Television receivers installed in moving objects,
4. Reception point in automotive vehicles; such antennas are also used as indoor television antennas.