【 Weak current College 】 common amateur radio frequency propagation 】

Amateur radio bands from low frequency to high frequency is divided into many discrete wavelengths, commonly used with HF band and VHF frequency band and the UHF band, high frequency and microwave frequency bands are used only for amateur satellite communications and microwave communication experiment. The following is a brief introduction about the popular amateur radio frequency propagation.

L.160m band (1.80 ~ 2.00MHz)
This is an amateur radio station allows the use of the minimum frequency. This band of communication patterns are very similar with the wave, the day is mainly ground wave close-up communication, evening through ionosphere D layer reflection distance communications, best communications opportunity is communication both at the time of sunrise sunset junction. In winter, dawn or dusk is 160m band long distance communication. Since this band frequency is lower, you need to set up a large antenna, ionosphere on its decay are also relatively large, need more power to achieve the long distance communication, as a result, the actions of people less, and liaison with the CW.

2.80m band (3.50 ~ 3.90MHz)
This band of communication law and similar 160m band, mainly to F and E hybrid transmission. Summer and day due to D and E layer of Electron density is high, the band following the wave will be absorbed and not by ionospheric, daytime only 100 ~ 200km distance communication. At the same time, frequent lightning in the summer, the band has a lot of noise, weak signal cannot be heard. In winter, dawn or dusk for long-distance communication of results than 160m band, long-range radio communications to opportunities. The band's antenna is relatively large, but compared to 160m band antenna has been reduced a lot, and now there are many shorter-products antenna so that the band antenna more difficult to reduce. General use of simple erection level half-wave dipole antenna, shortening of product wireless for vertical Earth-type of antenna, a large installation space and adequate funding to several tens of meters of Tower erection of huge Yagi! good antenna is to stand tall, and the length is enough.

3.40m band (7.00 ~ 7.10MHz)
This is a short-wave Starter entry band one of the most crowded busy band. This narrow-band operation range, but almost throughout all day mostly for QSO, daytime, you can make hundreds of kilometres of QSO in the evening or dawn is open long distance communications opportunity, many radio stations in the countries of the narrow band are crowded, plus its own band serious noise, into a bustling town map. At night, is often a good opportunity for intercontinental traffic, therefore, often in the band's HAM radio hunting rare and there is a "night owl". Domestic more HAM in 7.050 ~ 7.070MHz with LSB for QSO, many provinces also in some frequency set up fixed on the local network. The frequency of the antenna is simple dipole antenna, vertical ground antenna or complex Yagi directional antenna rotation can enjoy the fun, or even someone to shorten-whip antenna clips in automobile, travelling to wear Chau province QSO.

4.20m band (14.00 ~ 14.350MHz)
This band is the famous DX (long distance communication) band, because the band is mainly the ionosphere F layer for global communication. The band is characterized by a relatively stable transmission, the Sun and seasons change on propagation of the smaller ionosphere, opened a long time. Somewhat less in the winter spreading, spreading the main opening of Southeast Asia, and autumn began opening of global communication, in summer, even in the daytime and DX communication possible. The majority of international competitions and radio expedition activities in this band, while most use this band radio are also for DX communication purposes, therefore, this band is the best hunting rare radio band. In the domestic well-known is 14.180MHz frequency of Chinese old ham, dozens of years of Chinese in Southeast Asia every morning the old ham in the frequency of meetings, called tea together. Another is 14.330MHz frequency of China Radio Sports Association (CRSA) network, every Tuesday morning at ten, informed by BY1PK master, and activities around the CRSA recent work arrangements. The band apart from the popular CW and USB communication mode, you can conduct RTTY and SSTY communications. The band antenna can already do more compact, often using Yagi directional antenna, antenna gain is relatively high, is the use of multi-band antenna.

5.15m band (21.00 ~ 21.450MHz)
This is another short beginner beginners band, is also a good DX band. This band is mainly ionospheric F2 layer reflection, solar activity, days and nights and four seasons of change on the band's impact is large, relatively active when solar activity, this band is a main band DX, but solar troughs for long-distance communication difficult. In the spring and two quarters, you can open in the morning, afternoon, opening of the Americas, Oceania and Southeast Asia, the opening night of Europe and Africa. The majority of international competitions and radio expedition activities in this band. This band of background noise small, plus antenna size relatively small, with little power to DX communication, therefore, even in a city apartment buildings, small antenna installation conditions can also meet the requirements, even on the balcony or window out of the antenna can also be DX newsletter. At the same time, there are also many HAM with this band for mobile use, holidays in field erection up simple antenna, enjoy nature, you can also get DXQSO pleasure. In this frequency band is China in 21.400MHz amateur radio frequency of the calls, there are many Chinese HAM in this watch, but also many foreign radio stations dedicated to this frequency calls China's radio station. This frequencyRate fixed for DX number using high-gain directional Yagi rotation. Because the wavelength shorter, easier to self-made antennas, antenna for beginners to use self-made QSO 's.

6.10m band (28.00 ~ 29.70MHz)
This is the short wavelength of the highest band, is also the most short wavelength band wide band, the band propagation characteristics between HF and VHF, main features are affected by the impact of solar activity, unexpected E-layer communication phenomenon, once opened, ionospheric propagation attenuation small frequency noise is small, the antenna gain easy to do. In the ionosphere is no reflection, it can only be made-of-sight propagation. When spread open, they can be used very little power to unexpected long-distance communication. The band another feature is the only one in the HF band to the FM band, the FM signal is greater than the threshold, they have received very good immunity, since the role of finite amplitude circuits, signal to noise ratio and the sound quality is good, FM transceiver is also easy to make a simple adjustment, and production of a very high success rate. Therefore very suitable for beginners start self. The frequency is an international 29.600MHz FM call frequency, many domestic and foreign 10 m band FM enthusiasts with a QSO, FM transmission when opened, very lively. This frequency is using high-gain directional antenna and a variety of vertical antenna, self-made antennas of HAM.

7.6m band (50.00 ~ 54.00MHz)
This is the famous beginner beginners band, also known as "Magic Band". Mainly the band propagation characteristics between HF and VHF, between the active phase of solar activity, will produce unexpected E ionosphere propagation phenomena, the airwaves through sudden E ionosphere propagation of exceptions, you can use very little power for global communications of DX. The DX band fanciers adventures. In front of the band, amateur radio organizations in various parts of the world established the beacon platform, these beacons Taiwan 24 hours non-stop rotating beacon launch, we simply by receiving these beacons Taiwan's beacon signal, can real-time understanding of the band's line-up, and fans listen to record these beacons Taiwan signal conditions to explore unexpected E ionosphere occur and dissemination of magical law. In this frequency band famous call frequency is 50.110MHz, many 6m band DX hunters in the ambush, once opened, they earn the right media open short time for QSO. This band of wavelengths shorter, suitable for the antenna and circuit experiments. Now better the band handheld radio products, portable mobile use possible. Have heard that there is a small phone with 3W AM at their doorstep with Radio Japan liaison is magically experience Ah.

8.2m band (144.00 ~ 148.00MHz)
This is typical of VHF band, is a very active local mobile communication band. On the basic frequency band signal ionosphere, do not produce reflection wave propagation in direct wave range, transport large buildings in or mountain, and so on, will produce reflection, therefore, can be used only for short distance communication, at the same time, due to the carry out amateur satellite communications and the Moon's surface reflectance distribution experiment, for long distance communication. The band antenna is amateur radio productions with the highest rate, there are various high-gain directional and omnidirectional antennas, in-car Mobile whip antenna and compact handset antenna and so on.

9.0.7m band (430.00 ~ 440.00MHz)
Belong to the UHF band, the direct wave more than 2m band, reflection and refraction phenomenon than 2m band more obvious, but at the same time air attenuation ratio 2m band big, not suitable for long distance communication. When using long cables, begin to consider cable attenuation of signal generation. Since this band frequency is high, the noise is small, and the various manufacturers are racing to introduce more compact full-featured band antenna can be relatively small, you can set to auto, so that the band was very active in mobile communications. In order to address the issue of communication is close to many of the amateur radio enthusiasts to Repeater mounted in height, with poor turn signal Repeater, can greatly increase the communication range, enthusiasts just use very little power and simple antenna, and a distant radio QSO. In summer, the weather is stable season, regular production called "atmospheric waveguide" anomalous propagation phenomena (see Figure 12), radio in the atmospheric layer three-layer temperature jump back and forth between the attenuation is small refracted, passed away into the distance. There is also the Meteor reflection and tropospheric scatter, and other phenomena, it will also make 2m band propagation of radiowave horizon. This band of radio waves can travel through the ionosphere, the car radio and small cell phone, in recent years gradually replace 2m band, and a leading local mobile communication band, combined with the erection of a high-performance of the forwarding table, you can locally constitute a good distribution network. This band can carry out the Meteor reflections, tropospheric scatter, lunar surface reflection and amateur satellite communications, and other communication experiment, especially in recent years successively launched several high-orbit satellites for high-power amateur radio, enables the distribution time stretch, tracking easy, simple antenna requirements, equipment requirements, make use of satellite communications easier and therefore the participants to the public. In order to adapt to mobile communications, the band antenna mostly vertical polarization antenna, many manufacturers launch various 144/430MHz common dual-band antennas for amateur radio operators communicate between two frequency bands.

10.0.23m band (1260.00 ~ 1300.00MHz)
The band basic belongs to the microwave band, mainly in the form of direct wave propagation, but amateur radio is the use of this band for Meteor reflection and tropospheric scatter, and ultra distance communication experiment, in addition, there are also conducted by amateur satellite communications experiments. Since this band frequency is high, therefore the water vapor in the air and rain, etc. will have to wave attenuation, at the same time, the transmission cable and cable plug first class outages will be very large. Fortunately, due to the wavelength short, easy to use arrays or parabolic antenna, etc into a high-gain daysLine. Since this band frequency band is wide, so in addition to regular communication, but also for amateur digital communication and amateur TV communication experiment.