Antenna For HAM

Subject: Antenna For HAM 29th December 2008, 1:33 am

There are many different antenna designs but not all types suit all applications. Unfortunately many a radio guy has fallen into the trap of choosing the wrong antenna with the view to "get back the coax loss and more". Location is still the thing that counts most. Here is a list of the basic types, their radiation angles (with reference to the horizontal), and their prime suitable uses. Gains are all expressed as dBd (decibels over dipole).

1/4 wavelength "whip" (+45°):
This antenna is suited mainly to motor vehicles for use in densely built-up areas as most of the radiation is bounced off surrounding concrete structures. This type of antenna suits deep valleys in fixed locations. In all situations this antenna is reliant on a good groundplane. With a unity gain (0dB) this antenna exhibits the widest radiation pattern. The radiation angle is maximum 45° but may be lower with a 'drooping groundplane'. The maximum radiation is at ½-angle of angle between radiator and groundplane. Example: if the antenna is mounted on the roof of a vehicle with the angle between the element and groundplane being 90°, then the radiation angle is 45°.

1/4 wavelength "Helical" (+45°):
Also called "rubber duck" antennas, are used primarily for portable use as the spring design is exceptionally robust. These are not efficient antennas at all. The design represents a 1/4wave antenna that has been physically coiled into a spring. The fact the bottom bit is coiled up (this being the portion of an antenna that actually does the work) makes this portion of the antenna smaller in length. Having less "capture area" is what makes this antenna less efficient.

There is one advantage to the helical being the antenna tends to radiate in a more "isotropic" pattern therefore removing the need for the antenna to be in the correct orientation when transmitting - true 1/4-wave and higher need to be orientated correctly to work efficiently. As you can see, there is a trade-off (and why they still exist - ever wondered why they are found on cellphones!). Although I have always found it a little strange that by the time one reaches UHF that such antennas are still used! If one has to have the antenna shorter, then consider top loaded antennas where the bottom part (at least the first 1/8th wavelength) is uncoiled with the final portion then coiled up at the top.

1/2 wavelength whip with groundplane (+22°):
Very suitable for use in fixed locations in valleys. Although ideal for motor vehicles the sensitivity of the matching circuit needed for this type of antenna makes it impractical for this use as the bending of the whip or any dirt or water usually causes such a high mismatch the radio suffers. In fixed locations the bending and dirt ingress can be kept under control.

5/8 wavelength with groundplane (+15°):
A favoured antenna for motor vehicle use by offering a superb radiation angle which is sufficient for built-up area work yet low enough for rural work too. Not often found in fixed location models as the low radiation angle would not offer advantage over the ½ wavelength with groundplane. As the antenna is slightly longer than ½ wavelength it exhibits a small gain, typ 1.5dB. Many mobile models have been mounted on a good groundplane in fixed installations to make use of this gain.

Multi-element with groundplane (>+0°):
These antennas consist of various combinations of elements "popped on top of one another". The typical combination is ½-wave over ¼-wave, the two elements being connected to each other through phasing coils. The radiation pattern is dependent on the combination as well as the number of elements but a rule of thumb is the more elements, the closer to horizontal the radiation pattern. Use of these types of antennas is typically mobile UHF and SHF (cellphone) applications where gain is desired. Care should be taken as antennas with higher gain have a thinner radiation pattern and when flapping in the wind could cause signal variations.

1/2 wavelength w/o groundplane (0°):
Typical constructions are the centre fed dipole or endfed J-Pole and Slim-Jim (often mistakenly called an "Endfed Dipole"). This antenna is favoured for fixed location work offering unity gain and with the radiation pattern being the typical "doughnut" shape they offer both good local and distant coverage. As they work without groundplanes they are not suited to mobile work and performance suffers with the effects of nearby metal.

Multi wavelength gain antennas (0°):
Examples of these are "collinear" antennas. These are extremely suitable when distance is required without the need or desire to veer from the horizontal. These would be suited to flat plains or mountain top to mountain top where reflections or interference from valleys needs to be minimised. Not a good choice for a repeater system on a mountain top which is meant to cater for stations in valleys. Although the feed to the radiating portion of the true collinear is high impedance, some collinears are fitted with groundplanes to tilt the radiation pattern upwards when working in a valley.

Discone - (typ -10°):
It is surprising that there are not more of these antennas around, especially for use in repeater systems. They also have the wonderful characteristic of being very wide band, typically 10:1 of base frequency. A well designed discone could cater for all the typical VHF and UHF two-way radio frequencies of 66 to 480MHz and still have room to spare - all this with the added advantage of about 3dB gain from about twice the lower cut-off frequency. They do have two undesirable characteristics being extremely tricky to set up and do not have an inherent DC short thus are susceptible to inducing static in high winds. Although these are the negative points they are, none the less, extremely effective as repeater antennas and well worth the effort.

Stacked Arrays (-5° to -10°):
These are truly ideal antennas for mountain top repeater systems that are communicating with stations in the valleys below them. They exhibit both gain and the correct radiation angle and also, unlike the discone, have an inherent DC short. Please note when ordering such antennas to request the "tilt" option as stacks are also constructed to have the same 0º radiation pattern as per the collinear.

Directional Yagi (as required):
These antennas are suitable only in fixed locations where gain is required along a single path and/or interference from a known source needs to be minimised. Favoured for use in point-to-point links as using these help to keep the airwaves "uncluttered" by keeping the radiation to only the intended direction. Please note that not all constructions of Yagi antennas are suitable for minimising interference, thinking that all Yagis block signals from behind is a mistake. It takes a special construction to do that, usually at the expense of a little gain.

Subject: Re: Antenna For HAM 6th January 2009, 3:42 pm

yg mane lg bagus utk base zaxx??? zaxx,anda xjawab pun
soklan kita....huhu.........

Subject: Re: Antenna For HAM 28th January 2009, 12:43 pm

apa antenna yg terbaik?..makna nya sesuai tok rig.....apa makna antenna super gainner?

Subject: Re: Antenna For HAM 6th February 2009, 11:36 am

xtau la ape yg terbaik silent,sbb stakat ni cuma bru cuba satu brand je
...yg aku tau cuma 3 jenis@brand saje yg biasa rakan ham pakai sebab
kualiti antenna tu...Diamond MC101,Larssons dan Super Gainier.....
beza ketiga2 antenna tu pd penerimaan dan bila kita TX kot....mungkin
ZAXX,KEROL @ BRO boleh tolong jawabkan....hehe............

Subject: Re: Antenna For HAM 7th February 2009, 9:31 am

VC3FAD wrote:: xtau la ape yg terbaik silent,sbb stakat ni cuma bru cuba satu brand je
...yg aku tau cuma 3 jenis@brand saje yg biasa rakan ham pakai sebab
kualiti antenna tu...Diamond MC101,Larssons dan Super Gainier.....
beza ketiga2 antenna tu pd penerimaan dan bila kita TX kot....mungkin
ZAXX,KEROL @ BRO boleh tolong jawabkan....hehe............

lor...tuh bukan ham yg pakai...tp rakan2 kita heheheheheheh

Subject: Re: Antenna For HAM 11th February 2009, 3:39 am

aku nak try NR22L 2.46 meter beb...panjang siot...besh2...

setiap antenna ada yg dah siap fine tuning dan tak...contohnya kalo frekuensi amatuer kebanyakkannya mmg dah siap fine tuning maknanya takyah potong ke hapa...

kalo skrg vivac pakai frekuensi komersial..so kite kena tune balik mengikut chart yg disertakan bersama antenna yg dibeli...

td ada supergainer SG7200.. Rm rahsia...

pakli...antena base ada lagi panjang...7.2meter...ada bran???

Subject: Re: Antenna For HAM 11th February 2009, 1:44 pm

9M2 wrote:: aku nak try NR22L 2.46 meter beb...panjang siot...besh2...

setiap antenna ada yg dah siap fine tuning dan tak...contohnya kalo frekuensi amatuer kebanyakkannya mmg dah siap fine tuning maknanya takyah potong ke hapa...

kalo skrg vivac pakai frekuensi komersial..so kite kena tune balik mengikut chart yg disertakan bersama antenna yg dibeli...

td ada supergainer SG7200.. Rm rahsia...

pakli...antena base ada lagi panjang...7.2meter...ada bran???

ko kalu bab racun no 1...hampes

Subject: Re: Antenna For HAM 12th February 2009, 10:06 am

9M2 wrote:: aku nak try NR22L 2.46 meter beb...panjang siot...besh2...

setiap antenna ada yg dah siap fine tuning dan tak...contohnya kalo frekuensi amatuer kebanyakkannya mmg dah siap fine tuning maknanya takyah potong ke hapa...

kalo skrg vivac pakai frekuensi komersial..so kite kena tune balik mengikut chart yg disertakan bersama antenna yg dibeli...

td ada supergainer SG7200.. Rm rahsia...

pakli...antena base ada lagi panjang...7.2meter...ada bran???

zaxx,ape brand antenna tu??? bape dia punya db?? bg la dia punya spec betul2....mana tau aku berminat....hahahaha.....

cik widdy,jgn marah eh...sabo................... Laughing

Subject: Re: Antenna For HAM 12th February 2009, 1:01 pm

VC3FAD wrote:

9M2 wrote:: aku nak try NR22L 2.46 meter beb...panjang siot...besh2...

setiap antenna ada yg dah siap fine tuning dan tak...contohnya kalo frekuensi amatuer kebanyakkannya mmg dah siap fine tuning maknanya takyah potong ke hapa...

kalo skrg vivac pakai frekuensi komersial..so kite kena tune balik mengikut chart yg disertakan bersama antenna yg dibeli...

td ada supergainer SG7200.. Rm rahsia...

pakli...antena base ada lagi panjang...7.2meter...ada bran???

zaxx,ape brand antenna tu??? bape dia punya db?? bg la dia punya spec betul2....mana tau aku berminat....hahahaha.....

cik widdy,jgn marah eh...sabo................... Laughing

yg ada tuh tolak murah2 kat silent...heheheh

Subject: Re: Antenna For HAM 13th February 2009, 2:16 pm

yg zaxx kata ni antenna mobile ke base punya zaxx????huhu..........

Subject: Re: Antenna For HAM 13th February 2009, 4:55 pm

VC3FAD wrote:: yg zaxx kata ni antenna mobile ke base punya zaxx????huhu..........

yg supergainer tuh mobile...base tuh yg 7.2 meter.....

Subject: Re: Antenna For HAM 1st March 2009, 11:41 pm

En. Zax, antena super gainer tu ade brp jenis?

yg ssuai d mobile bsama rig TM271?

Bg pndapat ckit...

Subject: Re: Antenna For HAM 2nd March 2009, 9:51 am

9W2-FLC wrote:: En. Zax, antena super gainer tu ade brp jenis?

yg ssuai d mobile bsama rig TM271?

Bg pndapat ckit...

nk jd pengumpul antenna ker?

Subject: Re: Antenna For HAM 4th March 2009, 12:07 pm

yg zaxx cakap ni antena mobile ke base punya...zaxx xjawab pun...hehe

Subject: Re: Antenna For HAM 30th March 2009, 5:08 pm

9W2-FLC wrote:: En. Zax, antena super gainer tu ade brp jenis?

yg ssuai d mobile bsama rig TM271?

Bg pndapat ckit...

jenis-jenis supergainer boleh di lihat di link ini klik here Diamond Antenna Super Gainer

Subject: Re: Antenna For HAM 31st March 2009, 10:30 am

ok,thank joncy....huhu....skang ni silent bercite2 nak naikkan base antena....huhu....dh panas sebab xdapat nak QSO ngn rakan2 kelab...hehe..sabar silent...........

Subject: Re: Antenna For HAM 31st March 2009, 11:03 am

tau xpr...tp pelan2 kayuh....huhuhu

Subject: Re: Antenna For HAM 31st March 2009, 11:29 am

kalau bajet kurang utk base antenna.. dapatkan slimjim by silver... QRK dalam 60-70 shj... prestasi mmg tidak mengecewakan... ada rakan di penang yg pakai slimjim pada ketinggian 4 tingkat rumah flat letak plak atas tangki ayaq.. bleh simplex smpi perlis signal report RS 59 tapi berapa kuasa pancaran saya tak ingat...

Subject: Re: Antenna For HAM 31st March 2009, 1:00 pm

Tu la yg aku kata kan silent....pakai slim jim jek....huhu.........

Subject: Re: Antenna For HAM 31st March 2009, 1:10 pm

joncy,

pakai kotak itam ker bdk kecik?mana nk cari amp yek?

Subject: Re: Antenna For HAM 31st March 2009, 1:23 pm

saya bdk kecik pun ada kotak hitam pun ada... heehehe... kat base guna kotak hitam v8000 handy selalu bawak kemana sahaja dok dlm beg pack.. hehehe

Subject: Re: Antenna For HAM 31st March 2009, 1:37 pm

bukan..maksud saya...pakai base antnna guna bdk kecik ker leh tmbak jauh2...

Subject: Re: Antenna For HAM 31st March 2009, 1:56 pm

oic... tak... rakan saya yg memancar jauh tu guna icom 2200h tapi kuasa pancaran saya tak pasti berapa... bro.. kalau antenna tinggi.. guna handy pun leh memancar jauh kalau kena ngan propagasi dan ada window

Subject: Re: Antenna For HAM 31st March 2009, 2:19 pm

window?

Subject: Re: Antenna For HAM 31st March 2009, 2:55 pm

hehehe.. yg tu sy nk xplain tak reti... tapi saya paham... nk kena eyeball cerita baru lbh mudah paham...