ANTENNA FM VERTICAL 5/8 LAMBDA

Antenna system plays an important role in FM transmitter, Example:
Transmitter with a 150 Watt power output, SWR = 20: 1, 0 dB gain antenna. This antenna system has a performance / performance is worse compared to an FM transmitter with a power output of 25 Watt, SWR = 1: 1, and 6 dB gain antenna. This example shows how great the influence of the antenna system to the transmission of radio signals.

An important factor in the FM antenna system installation is the antenna height. In the VHF band, the requirement that communication can take place is a LOS (Line Of Sight). So ideally communications on VHF, both receiver and transmitter antennas both should be mutually visible. So that between them there should be no objects that can absorb radio energy. So that the amateur radio in the VHF band is often stated that it is better to have a small but gain antenna mounted antenna with a gain higher than a large but low mounted.

Vertical antenna 5 / 8 lambda below are very easy to make, and quite inexpensive. To "tune" enough lengthen or shorten pecutnya (whip). On the connections that can be mounted clamps tightened. These clamps are sold at auto parts store or motorcycle.

Antena Colinear VHF

6 dB VHF Antenna Colinear.

It is not too difficult to make a VHF antenna with omni-directional properties and has the advantage of 6 dB *. A "Slim-Jim" antenna is quite popular but only about 1.7 dB of gain realized *. I have a problem with my radio station package and decided that the antenna gain is the solution. So now I have a 6 dB gain VHF colinear. I also managed to get another 6 dB or more than my old receiver VHF IC260A tired-out with a little tuning agile. (* - Referred by a simple 1/4-wave whip antenna)

This image shows the basic construction. There is nothing new about the technology, the installation of a half-wave on top of another is very common. Both Marconi and Franklin developed a similar technique, but Marconi is more interested in the capacitive coupling between antenna elements whereas Franklin proposed 1/4-wave stubs in a variety of simple and complex forms (Antenna Engineering Handbook by Jasic). I attended Franklin antenna approach, but using a 4mm hard drawn aluminum rod, supported by cutting bits of nylon cutting board "liberated" from the kitchen (when the wife is not there - of course). Each element and stub are all calculated 1/2-wave length (1030mm) but the pilot had to be about 2 "(5cm) longer stub is folded to form two parallel bars. 5cm apart joined together at one end of the Second. The remaining elements of radiation as a single straight element. the three elements are formed is supported by two pieces and shaped blocks nilon.6 dB VHF collinear VHF Antenna Mount Antenna Mounting 6 dB collinear. I have yet to show the dimensions of the block cut but put in the first picture shows you exactly how they are formed. It all depends on what size wooden mounting boom you have. This of course can be metal, but I got a bit of wood sitting doing nothing on the balcony. The only thing that matters is that the pilot should be 1/4-wave length, excluding end shorted (folded).