GENERAL OBJECTIVE

The main objective of this project is to understand the working and the design of an antenna.

SPECIFIC OBJECTIVE

To design and build the antenna according to designed specifications. To be acquainted with some of the characteristics of parasitic antenna element

modelling and operation. To know the Antenna radiation pattern Test antenna and verify it performs as expected. The project system performance objectives are:

(a) Develop large, low cost antenna structure. (b) Validate mechanical packaging efficiency.

BILL OF MATERIALS

Item # Description Quantity Total cost(Peso)

1 Aluminium tube (3meter) 1pc. 75.002 Balun 1pc. 50.003 Aluminium tube holder 3pcs. 60.004 Bolts and nuts 3pcs. 15.005 Screw 3pcs. 3.006 Boom (3ft.) 1pc. 75.007 Coaxial cable (5 meter) 1pc. 100.00

Total cost: P378.00

PROCEDURE

1. Cut the three tubes to their exact lengths and drill a hole (1/16" diameter).The shortest tube will be used as a director element, the longest tube will the reflector element and the medium length will be the driven element.

Preparing the driven, reflector and director elements.

2. Cut the aluminium mounting tube or boom to 3 feet long and drill three holes thru and thru at one side. The holes must have a diameter of 3/8" or enough to accommodate the diameter of the tube that will be inserted into it. Follow the dimensions shown.

a = 3/8”

Preparing the boom.

3. Mount the aluminum tubes to the tube holder to the boom following the illustration for the proper arrangement of the elements. Secure the tube to the boom by placing the screws through the holes at the sides similar to the method of attaching element of the antenna.

Assembling the antenna elements to the boom.

4. Complete the attachments of the driven element by putting the balun into it and tighten the nuts through the wire.

DESIGN

Quantity Description Dimensions1 Aluminum tube (Reflector) 0.525m1 Alumnum tube (driven) 0.5m1 Aluminum tube (director) 0.475m1 Boom 1x1 3feet

RANGE: 50MHz-550MHz

CENTER FREQUENCY:

*550MHz – 50MHz = 500MHz

*500MHz / 2

*250 MHz

Fc= 250 MHz + 50 MHz

Fc = 300 MHz

Elements length:

For Lambda:

λ = C / F

= 300x10^8m/s / 300MHz

= 1m

Driven = λ / 2

= 1m / 2

= 0.5m

Reflector = 0.5m + 5%

= 0.5m (5%)

= 0.025m

= 0.5m + 0.025m

D = 0.525m

Director = 0.5m – 5%

= 0.5m (5%)

= 0.025m

= 0.5m – 0.025m

= 0.0475m

For Spacing:

S = λ x 0.2

S = 1m x 0.2

S = 200mm

S1 = S2

ACTUAL APPEARANCE:

DISCUSSION:

Operating frequency of vhf/uhf channels (Philippines)

Channel FREQUENCY RANGE TV STATIONABS-CBN CH. 2 54-60MHz

TV 5 CH. 5 75.5-81.5MHzGMA CH. 7 174-180MHzETC CH. 9 186-192MHz

NEWS TV CH. 11 198-204MHzIBC CH. 13 210-216MHzSBN CH. 21 512-518MHzSTUDIO 23 524-530MHz

NET 25 536-542MHzCITYNET 27 548-554MHz

RJTV 29 560-566MHzMTV 41 632-638MHz3ABN 45 656-662MHz

There are many different type of antenna that is in my option but Yagi antenna is one of the

most brilliant antenna designs. It is simple to construct and has a high gain, The Yagi antennas typically

operate in the HF to UHF bands (about 3 MHz to 3 GHz), although their bandwidth is typically small, on

the order of a few percent of the center frequency. This project is focused at frequencies ranging 50MHz

to 550MHz. exploring the effect of element length. A basic half wave dipole is cut to resonance at the

center of the frequency band and is utilized as the driven element. High gain is attained by the addition

of parasitic elements positioned either in front or behind the driven element. These parasitic elements

are called directors and reflectors depending on their length and positioning with respect to the drive

element. The reflector is longer by approximately 5 % and is positioned behind the driven element. The

director on the other hand is cut shorter by approximately 5% and is positioned at the front of the

driven element. The combination of these elements produce the directivity of the radiated signal thus

resulting to higher power gain. Since my frequency range is almost optimum to the Operating frequency

of vhf/uhf channels of the Philippines, All of the channel listed above was be able to pick up or receive

by the antenna. Even though I receive all the channel reception there are channels that are not clear but

watchable. There are many factors why are the other channels are not clear as the other channels, I

noticed that channel between the max and fc were crystal clear! Also in the between min and fc range

the channel were clear, example was the GMA 7 and the Studio 23. Three elements Yagi antenna is

standard, thus I believe that it’s not sufficient to receive the other reception clearly.

Broadcasts reception come from different towers, locations, and frequencies. Because of this,

some channels can come in great, and others not so well. For example; generally antennas are designed

to work best when pointed directly at the station. If the antenna is pointed north, all those channels

might come in great, but stations from the south may appear on your TV very weak. To troubleshoot

these types of issues take into account the location of the stations, which frequency they are using, and

how strong the TV station is broadcasting the signal. A general rule of thumb is that the larger the

antenna, and the more elements on it the better it will do for stations very far away. The reason for this

is because a big antenna with many elements on it will have a much better gain for each frequency than

a small one will. The results show clearly that the correction depends not only on boom spacing but also

in the element length.

CONCLUSION

Each antenna has its own advantages and disadvantages. It's not really possible to say that any

one antenna is best or worst. That determination can only be made on a case by case basis for each

installation. It is possible to create Yagi arrays with just two elements either a director driver

combination or a reflector-drive combination. However, Yagi’s acquire significantly more gain and a

better controlled front-to-back ratio when they employ at least three elements. Normally, for Yagi’s of 3

or more elements, there is one reflector and one driver, with additional elements being directors. The

Yagi antenna not only has a unidirectional radiation and response pattern, but it concentrates the

radiation and response. The more directors a Yagi has, the greater forward gain. As more directors are

added to a Yagi, it becomes longer. Some Yagi antennas have as many as 10 or even 12 directors in

addition to the driven element and one reflector. Long Yagi’s are rarely used below 50 MHz, because at

these frequencies the structure becomes physically unwieldy. Optimization of the Yagi Antenna can be

achieved by simulating the radiation patterns for various lengths of the element’s and the spacing

between them. I conclude that Yagi antenna has many factors that affect the radiation pattern, the

reflector size and spacing have negligible effect on the forward gain and large effects on the backward

gain and input impedance. More than one reflector provides little improvement on the directivity of the

antenna. The addition of more directors will increase the gain of the antenna although after the addition

of approximately 5 directors the advantages of adding more director’s decreases significantly. Generally,

receiver of Yagi antenna having some problem in receiving the signal. The function of these elements is

to enhance the radiation pattern in the source direction.

RECOMMENDATION

There are many variables to consider when designing for outdoor digital antennas, such as the

environment you live in, distance from your local stations, which channels you want to receive and so

forth. You must consider a multi-directional or bidirectional antenna, what you need depends entirely

on your specific situation. Indoor antennas are cheap, but only work if you are very close to the

transmission towers, you probably need to look into outside antennas. Bigger is better and Higher is

better It is a function of how many transmitter locations exist in your city and their relative location. It

depends on where you live and how far away the TV stations' transmitter towers are from you. If you

are in a city with the transmitters close by, then you should live close enough that set top with a loop for

UHF reception will do well enough. If you are in a smaller town or rural area then you'll have to invest in

an attic or roof antenna. For normal areas you might get into Yagi antenna and log periodic. We must

innovate antennas to determine how efficiency is we can get from it, especially now that the analog TV’s

are now getting phase out and the new HD TV are emerged. Innovating an antenna is a challenge to the

engineers especially when the time comes when Philippines decide to convert the analog signal to

digital signal for HD TV for better reception and also to the picture that would be clearer. Innovating

antenna is the next step for Electronics engineer to step up when it comes to digital communication

means.

Technological University of the Philippines-Taguig CampusKm. 14 East Service Road, South Super Highway, Western, Bicutan Taguig City 1630

ANTENNA PROJECT

SUBMITTED BY:

NICABERA, PATRICK JAY M.

SUBMITTED TO:

ENGR. BHAI NURAISHA IBRAHIM

DATE: MARCH 26, 2013