![]() Move the completed dipole into its approximate Total dipole length to be about 66 feet long, with each of the two segments at It’s easier to cut wire than to extend it, so let’s cut your In MHz), the total length of the dipole would be about 64.66 feet (64 feet, 8Ĭut the dipole wire to be a little longer than theĬomputed length. Using the formula to calculate dipole length (468/frequency Compute theĪpproximate antenna length for the center frequency of the range for which youĪre trimming–about 7.238 MHz. The General Class phone frequencies of 7.175 MHz to 7.300 MHz. ![]() For example, you may want to trim a 40 meter dipole for Pencil/paper/calculator to do the math, and wire cutters to trim the antenna.ĭetermine the band and frequency range you want You’ll need an antenna analyzer, coax connection to the antenna, Now let’s look at the steps for tuning a dipoleĪntenna. Some models allow a wider scan of a single band or multiple bands. You can watch for the SWR value to dip to a minimum value, and see the precise frequency for which the antenna is currently trimmed. Using the built-in menus and controls allows the user to move through a range of frequencies while observing the SWR readout. It connects to the feed line, generates its own RF signals for the antenna system, computes SWR, and displays it along with the frequency. The most common tool used to help you adjust the antenna is an antenna analyzer. Should adjust for a low SWR in your antenna system. Indicate greater reflection and less efficient power transfer. Reflection and efficient power transfer to the antenna, while higher SWR values Your antenna system with the reflected power. The standing wave ratio (SWR) is a comparison of the forward power in Little power reflection due to some impedance mismatch at the antenna feed Nearly all antenna systems will have at least a ![]() Your transmitter’s power will be reflected back down the feed line instead of Impedances match, your antenna system will radiate efficiently. Trimmed, the antenna feed point will present an impedance that is closely Length to the operating frequency you plan to use. Trimming a dipole antenna means adjusting antenna You a lot of frustration and get you on the air in a short amount of time. Learning to tune an antenna is important to ham radio operation. You’ve measured twice and cut once, yet the SWR readings are higher than you think they should be.Īlthough it’s not exactly a crucial life skill, The matching transformer has several tap settings, allowing for a number of antenna resistance selections.You’ve gone to great lengths to make sure your antenna is cut for the proper frequency using the 468/MHz formula. The capacitance value supplied in the LF/MF Antenna Simulator will be dependent on the model of the ATU with which it is to be used.Ī fixed-tapped matching transformer transforms a 50 ohm resistive load (customer supplied) to a lower resistance which is representative of a typical value of antenna ground plane system resistance. Suitably rated, high voltage RF capacitors provide a fixed capacitance value which is equivalent to the capacitance that can be expected from a typical antenna system. Simulated and Fixed antenna capacitance. ![]() The antenna simulators provide maintenance personnel with a typical static antenna load found at LF/MF transmission sites to allow for full testing of the ATU. ![]() Nautel offers antenna simulators for use with Nautel Automatic Antenna Tuning Units (ATU’s). LF/MF Antenna Simulators (Low Power and High Power) ![]()
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