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40M antenna survey - 2010/04/26 22:19 J'aimerais savoir d'un peu tout-le-monde quelle antenne seriez vous prêt à installer pour 40M à votre station. Une antenne qui reponds à vos critères de budget et d'espace disponible.
Voici les choix:
sloper
V inversé
verticale 1/4 onde
dipôle vertical
dipôle filaire horizontal
dipôe rotatif (rotatable dipole)
Moxon beam raccourci (19 ft boom et 30 pieds de longueur)
Yagi 2 éléments raccourci (boom 18 pieds et éléments 43 pieds)


So what would your choice be amongst these 40M antennas, something that you would LIKE to put up at your current location. Something realistic of course not just in your wildest dreams hi.

Avez vous des suggestions à partager avec le groupe? Shoot...

73,  Fabi
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Re:40M antenna survey - 2010/04/30 17:57 Hello Fabi

I'm using a full wave 40m horizontal loop, also known as a Skywire antenna, here in a small city lot with good results.

I made an Extended Double Zepp for the 2006 RAC Winter Contest. We operated from VE2LCM's QTH wich have the room for such an antenna. The antenna performed also quite well. I paid a particular attention to model the antenna and the open wire matching stub to optimize it. But this antenna have two narrower main lobes, two smaller lobes and more nulls than a dipole.

Personnaly for me a reasonable antenna I'd like to try on 40m would be the rotatable dipole.

This was my 2 cents. (HI)

Good question Fabi!

73 de Louis, VE2EZD
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Re:40M antenna survey - 2010/04/30 19:35 I already have a 80/40m inverted vee, apex 45ft and the results are medium.
With the new 64ft tower I will try two halfwave sloper for 40m, one for USA and the second one for EUrope. Will see the F/B when switching them. Depending of results I may had a 2 el. beam fix for EUrope and keep the slopers for USA and turn the second one south.

73 de Claude VE2FK
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Re:40M antenna survey - 2010/05/01 17:27 Salut Fabi,

D'une manière générale, les simulations montrent que sur 40m, une antenne horizontale devient plus performante qu'une verticale même élevée dés lors que l'antenne horizontale se trouve à plus de 15m de haut.

Comme tu le sais, j'ai la yagi deux éléments racourcis que tu mentionne à 22m de haut. et je pense évidement qu'en émission ce sera la plus performante de toutes celles que tu cites.
Ce qui devrait faire fortement refléchir , c'est qu'aucune des antennes citées, y compris la mienne ne sont très performantes en réception. Or le 40m est de mon point de vue la bande la plus bruillante ici, probablement à cause des distances de skip idéales pour recevoir les QRN d'orages en Floride, sur les rocheuses/centre des USA et sur l'océan Atlantique
Donc je pense que le choix le plus important pour performer sur 40m ce sera une bonne antenne de réception prioritairement à essayer de gagner 3dB en émission qui frustreront encore plus tes correspondants qui t'entendront mieux mais que tu n'entendras pas.

73 Gilles VE2TZT
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Re:40M antenna survey - 2010/07/28 19:22 Bonjour Fabi,

Après avoir lu tout cela voici mon point de vu Fabi.

Pour le DX  

Par expérience,  pour le 40M j'ai eu dans un espace très petit un 2el et un 3el Yagi.

le 2el 402-ba de hygain a 48 pieds m'a apporté mes premiers dx LP avec VK ...

mais 50pieds pour un beam de 40m ca vaut pas grand chose.  Trop de perte par l'effet de sol qui n'ajoute pas de gain dans la direction souhaité.

J'ai eu un 3el 40M a 60' mais c'est seulement quand je l'ai monté a 75pi qu'il a vraiment commencé a performer.

75'  105' sont des hauteurs minimum pour vraiment investir dans un beam de 40M.

En bas de 75' pieds un beam de 40m est une perte d'argent, à moins que comme dans mon cas il n'y a pas de place pour une verticale.

Mais comparé a une loop ou V inv a 48 pieds oui le beam a 48pi était supérieur.


Avec du terrain et de l'espace les verticales sont la pour dominer le vrai dx ...et ca a bien meilleur cout

...les installations de rotor, mat etc sont très couteux pour notre climat pour des beams sur 40m surtout full size.


Après tout on cherche pas améliorer les régions que l'on contacte facilement mais ce que l'on entends pas et que les autres contactent facilement !

Il y a aussi une question a savoir tu veux avoir l'avantage de la communication pendant combien de temps durant la journée. Ou des heures fixes ?... les deux polarisations ne fonctionne pas à la même heure...


Salutation 73' Phil VE2FU

Post edited by: VE2FU, at: 2010/07/28 19:30
Phil VE2FU
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Re:40M antenna survey - 2011/03/10 22:50 CGQ
BEST ANT PR 40M

BEST ANT. FOR LIMITED AND UNLIMITED SPACE AT LOW HEIGHTS and for

80m as well as for 40m is a pair of phased dipoles.
Space required on 40m is half wave long for each dp, spaced 33 feet.

Yes 30' high is plenty high, because the phasing will take off that high

worthless angle to put your precious watts in the low angle lobe. This

gives you great front to rear as well if you care for it.

And phasing for 2 dipoles is no black magic. You just add a quarter wave

piece of coax to the element you want to be the front of your array. You

then switch it to reverse direction. Be aware that that coax may not be 90

degrees long, due to the Z of your dipoles. It may end up being 115 or

120 degrees long for optimum results. You will hear the diff. in the

receive performance, even if you only listen to the noise!

For 40m, you can even put three phased dipoles in a square of 66feet

wide by 66' long (33' between each dp), for added gain and f/r. Phasing is

a little bit more fun here, but again no black magic.

As for verticals for lower angles AND NILL NOISE (YES VERT. POLAR. WITH

NO NOISE), you need 2 supports spaced 45' and about 35 feet high.
You then hang a CVA (sort of a shorted bottom bobtail to give you the

50ohms Z rather than the 2000 ohms of the bobtail).  AND it could care

less about the ground under; so no radials needed: it wont help. Model it

you see.

BUT if you space those 30' supports at 95 feet, you can a real grass

burner made up of 3 verticals, shorted across their tops AND bottoms and

beating the four square (with its four supports and how many radials?).
Again 50 ohms Z and feed anywhere on ANY of the verticals. 50 ohms

anywhere. And because they are a dc short, you get nil noise and no static

build up. They are even quieter than a beverage; believe me i've done it!
Then the penultimate, add such an array 33 feet behind the first one and

get BETTER GAIN than a real 6 square with its six support and 120?

radials.
Again CVA needs no radials and could care less about the state of the

ground under.
To sum up, i'd use 2 CVA (six verticals) on any band (90'WX33'LX35'H on

40m).

roy, va2gu[size=4][/size]
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Re:40M antenna survey - 2011/03/11 11:10 Hello Roy

Your website is VERY interesting and reading it will keep me busy for the next few days.

Glad to see people using the compex number facilities in Excel to solve some impedance related problems. I made a spreadsheet using complex numbers to calculate the matching stub of a 40m EDZ. By the way those 450 Ohms window lines are below the advertized 450 Ohms. This figure is more of a generic name than the real characteristic impedance of the line. I modelized the antenna with MMANA and imported the R + jX *.csv file into my Excel worksheet to find the optimized stub length. The antenna worked very well.

Your CVA antennas seems very promising and I will give them a try.

Thanks for sharing your work with us.

73 de Louis VE2EZD

Post edited by: ve2ezd, at: 2011/03/11 11:11
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