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INVERTED VEE ANTENNA

Sumber artikel ini saya ambil dari postingannya Om Djoko Haryono di Facebook Group HOME BREW

PROJECT ( CB RADIO, ANTENNA, SWR, AUDIO, MICROPHONE, BOOSTER, etc )

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Antenna V terbalik ( Inverted Vee ) adalah antenna sejenis dipole yang sering dipakai sebagai pengganti bila

pemilik radio tidak memiliki lahan yang cukup luas untuk membentangkan dipole. Kedua ujung antenna

dipasang / ditarik kearah ( mendekati ) tanah , sedang bagian tengah antenna ( feed point ) diangkat tinggi

dengan menggunakan tiang.

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Sudut antara kedua kaki / sisi radiator harus antara 90 s/d 120 derajat ( minimal 90 derajat ). Pada sudut inibesarnya impedansi pada feed point maupun panjang yang dibutuhkan bagi bagian lambdanya akan kurang

lebih sama dengan dipole.

03

Pada sebagian besar kasus , panjang dari bagian2 tsb. umumnya akan menjadi ( ketemu ) sebesar 1 sampai 6 %

lebih panjang daripada dipole. Berapa panjang yang paling memberikan hasil optimum ( diantara 1 s/d 6 %

tersebut ) , sebaiknya di trim / pruning menggunakan SWR meter.

04

Gain dari antenna Inverted Vee lebih rendah daripada dipole karena antenna jenis ini kurang directive dibanding

dipole , namun ada keuntungan pengganti lainnya yang kita dapat dari Inverted Vee yaitu arah sudutpancaran

( angle of radiation ) nya yang lebih rendah juga dibanding dipole. Ini memberikan keuntungan lain yaitu

antenna ini lebih cocok untuk komunikasi DX jika dibandingkan dengan dipole karena komunikasi jarak jauh

pada HF lebih membutuhkan sudut pancaran yang rendah.

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Inverted Vee lebih popular pada pemakaian di band2 yang lebih rendah ( contoh : antara band 80 sampai band20 meter ) khususnya bagi mereka yang lahannya terbatas. Bagian Apex ( puncak atau center antenna )

sebaiknya disangga dengan menggunakan tiang bambu , atau bisa juga menggunakan tiang kayu yang tidak

terlalu panjang tetapi dipasang diatas tengah2 genting rumah.

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Rumus panjang total dari radiator atau element antenna ( sisi kiri plus kanan ) bisa dihitung dengan L (meter ) = 151,198 : Freq ( MHz ) , atau dalam feet L = 496,08 : Freq ( MHz ). Atau tiap sisi antenna , dalam feet

panjangnya adalah 248,04 ( alias sekitar 1.06 X lebih panjang dari dipole ) : Freq ( MHz ).

Djoko Haryono.

http://radiotengkorak.blogspot.com/2012/07/inverted-vee-antenna.html

Introduction

http://radiotengkorak.blogspot.com/2012/07/inverted-vee-antenna.htmlhttp://radiotengkorak.blogspot.com/2012/07/inverted-vee-antenna.htmlhttp://4.bp.blogspot.com/-THSroETCnxA/UAlxsCnyE4I/AAAAAAAAAts/AiRmI6fiC-g/s1600/Inverted+V+Dipole.jpghttp://radiotengkorak.blogspot.com/2012/07/inverted-vee-antenna.html

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As you can see from the diagram on the right, this antenna gets it's name from the shape. It's reallyjust a dipole with the center raised on a mast and the endpoints near ground. By raising the centerpoint, the horizontal space requirement is reduced and only one tall support is required. Although notthe same as a dipole at the recommended height of 1/2 wavelength above ground, it is still veryeffective when space is a premium.

Another characteristic is that there is ashortening of the radiator element by 3 to 5percent. This will cause an antenna, that wasinitially meant for another configuration, torequire some pruning once installed.

Yet another characteristic is the radiation pattern.A standard dipole generates a horizontal ratiationpattern in the shape of a figure 8, with maximumradiation broadside to the antenna. The Inverted-Vee tends to be more omni-directional andradiates equally in all directions.

For best results with this type of antenna, theApex Angle should be kept between 70 and 110Degrees. Below 70 Degrees the radiators start tobecome parallel to each other and signalcanceling will start to occur. Above 110 Degreesthe antenna starts looking like a standard dipole,minimizing any of the feed impedance andshortening effects. The optimum Apex Angle is90 Degrees.

Program Description

The Data Input section, below, is set up for youto enter data. You only have to fill in the textboxed with known data and the rest arecalculated. You can choose to specify afrequency of operation and let the web pagecalculate and use that for the Radiator ElementLength. Or, you can specify your own value forthe Radiator Element Length. Any time youchange any of the input data, the output data isautomatically re-calculated.

If the Support Height (Hs) is not set orset to zero a small height (0.001 Ft) isassumed to avoid some divide-by-zeroproblems.

If you select any of the Check Boxes,some of the input data areas will begrayed out and not allow any input. Tore-enable these input area Un-Check theappropriate Check Box.

If too much data is left undefined, the

program will start to make some

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A few things to note are:

The equations behind this web page arereally just a geometric solution, so, thispage can be used with any type of wire

antenna, dipole, trap-dipole, folded-dipole, etc..

It's OK to mix and match dimensions.The web page does all calculations inUS/Imperial measurements and convertson input and output, as necessary.

The Radiator Arm (Ra) length, in thediagram, is measured from the Apex tothe top of the End Support and thusincludes the Radiating Element AND theEnd Insulator. The Input Data areaprovides space for specifying them bothseparately.

assumptions. It may be benificial to startthis way, see what the program comesup with, and then adjust the input data.For example, if you only define theRadiator Element and End Insulatorlength, the web page will assume a Apex

Angle of 90 Degrees and calculate therest of the information. You can thenmake changes as you see fit.

I tried to intercept all possible entryconfigurations and error conditions but afew still remain. I will fix them when I getaround to it but if there is something thatreally bothers you, send me email.

Data Input

Freq. (MHz)

7.100

ReductionPercentage

4.0 Percent

Using a Center Frequency of7.1 MHz for theDipole, yields a length of32' 11-1/2" (10.07 M).

Reducing this by 4.0%, to account for the

Inverted Vee configuration, we have a lengthof31' 7-3/4" (9.668 M).

Radiator Element

Ft

End Insulator

8

In

Use the Inverted-Vee value, calculatedabove, for the Radiator Element

Fix Apex Angle at 90 Degrees

Apex Angle (Deg.) Horizontal Space (A)

50

Ft

Mast Height (Hm)

Ft

Support Height (Hs)

Ft

Data Output

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http://www.k7mem.com/Electronic_Notebook/antennas/inverted_vee.html

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