Earning a Technician Amateur Radio license is a good way to begin enjoying ham radio. There is no Morse code exam for this license, and the Element 2 written exam is not difficult. There is no difficult math or electronics background required. You are sure to find the operating privileges available to a Technician licensee to be worth the time spent learning about Amateur Radio. After passing the exam, you will be able to operate on every frequency above SO megahertz that is assigned to the Amateur Radio Service. With full operating privileges on those bands, you'll be ready to experience the excitement of Amateur Radio! You also gain privileges on the 80, 40, IS and 10 meter HF bands.
Perhaps your interest is in Amateur or "ham" radio's long history of providing emergency communications in time of need. Your experience with computers might lead you to explore the many digital modes of amateur communication and networking. If your eyes turn to the stars on a clear night, you might enjoy tracking the amateur satellites and using them to relay your signals to other amateurs around the world! Your whole family can enjoy Amateur Radio, taking part in outdoor activities like ARRL Field Day and mobile operating during a vacation.
Once you make the commitment to study and learn what it takes to pass the exam, you will accomplish your goal. Many people pass the exam on their first try, so if you study the material and are prepared, chances are good that you will soon have your license. It may take you more than one attempt to pass the Technician license exam, but that's okay. There is no limit to how many times you can take it. Many Volunteer Examiner Teams have several exam versions available, so you may even be able to try the exam again at the same exam session. Time and available exam versions may limit the number of times you can try the exam at a single exam session. If you don't pass after a couple of tries you will certainly benefit from more study of the question pools before you try again.
Bandwidth-The width of a frequency band outside of which the mean power is attenuated at least 26 dB below the mean power of the total emission, including allowances for transmitter drift or Doppler shift.
Beacon station-An amateur station transmitting communications for the purposes of observation of propagation and reception or other related experimental activities.
Broadcasting-Transmissions intended to be received by the general public, either direct or relayed.
Control operator-An amateur operator designated by the licensee of a station to be responsible for the transmissions of an amateur station.
Control point-The locations at which the control operator function is per¬formed. Earth station-An amateur station located on, or within 50 km of, the Earth's surface intended for communications with space stations or with other Earth stations by means of one or more other objects in space.
Frequency coordination-Allocating repeater input and output frequencies to minimize interference between repeaters and to other users of the band.
Grace period-The time FCC allows following the expiration of an amateur license to renew that license without having to retake an examination. Those who hold an expired license may not operate an amateur station until the license is reinstated.
One-way communications-; Transmissions that are not intended to be answered. The FCC strictly limits the types of one-way communications allowed on the amateur bands.
Peak envelope power (PEP)- The average power of a signal at its largest amplitude peak.
Prohibited transmissions-Certain types of transmissions, such as music and obscenities, that the FCC doesn't allow on the amateur bands.
RACES (Radio Amateur Civil Emergency Service)-A part of the amateur service that provides radio communications only for civil defense purposes.
Repeater station-An amateur station that automatically retransmits the signals of other stations.
Space station-An amateur station located more than 50 km above the Earth's surface.
Temporary state of communication emergency-When a disaster disrupts normal communications in a particular area, the FCC can declare this type of emergency. Certain rules may apply for the duration of the emergency.
Third-party communications-Messages passed from one amateur to another on behalf of a third person.
WRTC 2010 in Russia World Radiosport Team Championship หรือโอลิมปิกวิทยุสมัครเล่นจัดขึ้นทุก ๆ 4 ปีซึ่งในปี 2010 นี้เป็นโอลิมปิกวิทยุสมัครเล่นครั้งที่ 6 ประเทศรัสเซียเป็นเจ้าภาพ ...
Most antenna articles include these diagrams — but how do you interpret them? บทความโดย Joel R. Hallas, W1ZR จากหนังสือ QST (ฉบับ December 2009)
Atruth about antennas is that all real antennas radiate better in some directions than in others. It is thus important for hams to know which directions will work best, so the appropriate antenna, antenna height and orientation can be selected. A good way to describe how antennas perform is to plot their response. To some of us, the meaning of such plots is intuitive — but perhaps that’s not true of all our readers. In this short article, we’ll try to take some of the mystery out of this topic.
For a horizontal half wave dipole, the radiating field that leaves with maximum strength is in a direction perpendicular to the dipole. The field strength is reduced as we move in the direction of the ends. Near the earth, the field cancels at the horizon and increases to a maximum at some angle above the horizon depending on how high off the ground the antenna is.
Plotting Antenna Response
Rather than discuss this in general terms, we can represent the directional effects of the antenna in plotted form that can be easily interpreted. We could plot the field strength as a function of azimuth angle, the angle moving from, for example, far left to far right at a particular elevation angle, using familiar rectangular coordinates. We have plotted both the relative strength of the radiated power of such a half-wave antenna in Figure 1.
Figure 1 — Calculated relative field strength shown in rectangular coordinates.
Polar Plots While a representation such as Figure 1 is correct and useful, it is more common to show the information in something called a polar plot. This kind of plot represents the intensity in a particular direction by the length of a line from the center of the plot to the curve at any angle. This gives what seems to me to be a more intuitive view of the performance of the antenna as a function of the angle.
Figure 2 — Polar plot of modeled relative power vs elevation angle. The end view of the wire antenna is shown as a dot. The green arrow points in the direction of maximum signal strength and its length represents the maximum signal amplitude. The red arrows point to the elevation angles at which the relative power has dropped to half that (–3 dB) of the maximum signal strength; the angle between them is the 3 dB vertical beamwidth. Figure 2 is a representation of the field strength from a thin 40 meter dipole 60 feet above typical ground. This is shown as a function of elevation angle taken in the direction perpendicular to the antenna wire, the azimuth angle of maximum output. Note that the field at the horizon is zero, as we would expect for a horizontal antenna over real earth. Note also that at this height of 60 feet, the radiation upward is reduced and the maximum radiation is at an elevation angle of 32° above the horizon. It is easy to see from the rings, shown in decibels, that the response straight up is down 10 dB from the maximum. This will be different for different heights. Although this antenna is bidirectional, only one set of arrows is shown.
Figure 3 — Polar plot of modeled signal strength in decibels (dB) as a function of azimuth angle at the maximum elevation angle, 32° for this height. The antenna orientation is shown, so consider this looking down from above. As in the elevation pattern, the green arrow points to the azimuth angle of maximum strength at 90°, or perpendicular to the wire, as we would expect. The red arrows point to the azimuth angles at which the power has dropped to half the maximum, the 3 dB horizontal beamwidth. Figure 3 is a polar plot of the radiation from the same dipole at an elevation angle of 32°, the angle of maximum radiation. The angles correspond to the same angles as shown in Figure 1 and represent the relative strength in different directions going around the antenna from 0° at a wire end all the way around clockwise to the same point, 360°. The relative power is generally shown in decibels (dB), a convenient logarithmic representation that makes it easy to add up system gains and losses. Note that the dB scale is compressed to show additional detail in the more significant portion.