The Isotron AM Antennas are the perfect AM broadcast antenna for all broadcast band AM transmitters from 300 to 1000 Watts! There are ten models available to cover the entire AM broadcast band. Order the model that covers the frequency you will be using. Antennas are factory tuned to your frequency but require minor assembly and adjustment by the customer. Requires NO GROUNDING SYSTEM so it's incredibly easy to install. Includes complete instructions for tuning and use. Antennas are built to order, Allow 1-2 weeks for delivery.
SPECIFICATIONS: Model 200 - Max Length 164" Approx Wt 9lbs, Model 200B - Max Length 103" Approx Wt 7lbs, Model 200HP - Max Length 165" Approx Wt 10lbs, Model 225 - Max Length 235" Approx Wt 11lbs, Model 400 - Max Length 27' Approx Wt 18lbs, Model 600 - Max Length 38' Approx Wt 30lbs
Wind Load (sq. feet): 1.69, Wind Rating: 85, Pattern: Omni, Connector: SO-239
The Isotron AM Antenna design is an electrical copy of a 1/2 wave dipole. Radiation patterns and formulas are not necessary for analyzing the tuning characteristics.
- A 1/2 wave dipole reacts as a SERIES RESONANT CIRCUIT. All electrical formulas you want to apply to this circuit will also apply to the antenna AT THE FEEDPOINT. The feedpoint is what determines how the antenna will match the transmitter and measurements taken at the connector of the antenna. Therefore whether the circuit is on your radio board or hanging as an antenna, all formulas and theories apply.
- At the feedpoint the dipole or Isotron AM Antenna will resonate. This is when the Capacitance Reactance (XC) and Inductive Reactance (XL) are equal (value in ohms). However, when this takes place, because the antenna is a radiator it will also develop a pure RESISTANCE (R) when resonant or Radiation Resistance. This R is dependent on the antennas grounding, feedline and environment. This R value is what establishes your SWR measurment at resonance. Once an antenna is resonant it becomes a working device with a radiation resistance of 25 ohms or greater.
- When the antenna has a higher XC value than the XL the antenna is off resonance. The resonant point is at a higher frequency than where the transmitter is currently set. If the XL is greater than the XC the opposite is true. Off resonance the Impedance (Z) of the antenna increases. It will be at its lowest value at the resonant point. (Z and R are not the same)
- Testing an ISO AM Antenna at the feedpoint without the feedline is fine for design work, but is not practical for tuning it to your entire set up (radio, feedline and grounding). The antenna is an infinite extension to your feedline. They both must be tested together to have reliable results.
The Isotrons have been built physically to have proper capture area to the atmosphere. Enlarging the antennas more will have little affect on performance. The Isotron AM Antennas are not a loop, therefore, the radiation pattern is omnidirectional and polarization is random. Reception is noticed as soon as the receiver is connected. Low noise, good sensitivity and the affects of changing polarization is lower.
*Please note these antennas are exempt from PC Prime