antennas for the low bands..80 and 160m

8/8/2019 Antennas for the Low Bands..80 and 160m

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nnas for the Low Bands..80 and 160m

/ /www.iol.ie/~ bravo/low_band_antennae.htm[5/20/2009 12:37:45]

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Copyr igh t 1995 - 2008 John Tai t Al l r igh ts reserved.

Antennae fo r t he Low

Bands..80 and 160m

My TX Ant ennae

My K9AY RX Antenna

I f you l is t en to the DX ac t iv i t y on the Low bands, you 'd

be fo rg iven fo r t h ink ing tha t you ' re w as t ing your t ime

unless you have a 4 Square Ar ray , 20 ac res o f Beverage

antennae, a huge Ampl i f ie r , and a neck l ike an anv i l . .

We probably asp i re to hav ing t he lo t , but t hankfu l ly , we

can do a passab le job w i thou t any o f t hem. Those o f us ,w ho l ive in average homes, w i th average s ized gardens,

and sma l l t o average bank accounts , can be surp r is ingly

success ful l on t he Low Bands , once w e unders tand w hat

the min im um requi rements for succ ess are..

Real ly , The m a in a rea o f impor t ance is t heant enna f arm ...!!

On the h igher bands, the same antenna is usual ly used

for both TX and RX . The Low Bands are d i f ferent , in thatone good TX antenna is probably adequate. If the TX

antenna i s re la t i ve ly ine f fi c ien t , w e can compensa te by

us ing m ore pow er . But for RX, w e requ i re antennae t hat

have t he very bes t s igna l -to-no ise ra t io (SNR) that w e

can must er . I t is a lso very advantageous i f t hese

antennae are d i rec t iona l . Sens i t iv i t y in the RX ant enna is

not rea l ly that im por tant , so long as t he SNR is

ex cel lent . .. ..A good low noise am pl i f ier (pream p/LNA) can

g ive us a l l t he sensi t i v i t y t ha t w e need .

My TX An t enna e... .. !!

Fi rst o f a l l I mus t qua l i f y my remarks by s ta t ing tha t ALL

antennae benef i t f rom a good ground under t hem. (

exc ept the Beverage... "The ex cept ion proves the ru le"

)
http://www.iol.ie/~bravo/index.htmhttp://www.iol.ie/~bravo/hot_list.htmhttp://www.iol.ie/~bravo/index.htm#contactinfohttp://www.statcounter.com/http://www.iol.ie/~bravo/index.htm#contactinfohttp://www.iol.ie/~bravo/hot_list.htmhttp://www.iol.ie/~bravo/index.htm


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One area o f my garden has lo t s o f rad ia ls , bur ied w i re

mesh e t c . . I have run m any ver t i ca ls on th is s i t e o f

var ious t ypes. .. 1/4 w /l ver t ic als , inver ted Ls. .. t rapped and

o therw ise , and t hey a ll w orked w e l l . The Ver t i ca ls have

never been more than 50f t h igh, so var ious forms of

loading have been used t o b r ing them to resonance .

Typ ica l o f t hese w ou ld be my 80&40mVer t i ca l . Being a

fan o f L B Cebik W4RNL and h is exc e l len t s i t e a tCebik.com , I learned t hat t he MOST ef f ic ient form of

loading w as "capac i t y ha t " loading . I bu i l t va r ious

an tennae us ing t h is method , and they w ere the m os t

succ essfu l 1 /4 w /l ver t ica ls t hat I 've ever bu i l t .

I f ound an in te rest ing p ro jec t on LBs s i t e cons ist ing o f a

t r iang le o fthree ver t ic a l D ipo les . Shor t ly a f terw ards I

d iscovered Don K 2KQ's exc e l len t an tenna w h ich he ca l l s

h is Double L

. Th is is probably one of t he qu ick estlow band antennae t o dep loy, and is very ef fec t ive . I t

does no t have t he overhead nu l l of t he t yp ica l ver t i ca l ,

bu t i s a good DX an tenna , and c an a lso be used fo r

relat ively loca l QSOs.

I t hen ran ac ross "Another Way to Look at Vertical

Antennas"by Rudy Severns N6LF (March 1999 QEX).. .

Th is was the " i c ing on the cake" ... No t a lone had Rudy

got a l l t he p rac t i c a l s tu f f t hat I needed in the a r t i c le , he

a lso had t he gain f igures for h is ver t ica l d ipo lescom pared t o t rad i t iona l ( 1 /4 w /l ) ver t ic a ls ...In teres t ing

reading. .

(A drawing to show the progress ion f rom s t andard d ipo le , to Capac i t y hat ted,end loaded , ve r t i ca l d ipo le )
http://www.iol.ie/~bravo/80&40mVertic.htmhttp://www.cebik.com/http://www.cebik.com/vhat.htmlhttp://www.cebik.com/vhat.htmlhttp://www.yccc.org/Articles/double_l.htmhttp://rudys.typepad.com/ant/files/antenna_vertical_groundplane.pdfhttp://rudys.typepad.com/ant/files/antenna_vertical_groundplane.pdfhttp://rudys.typepad.com/ant/files/antenna_vertical_groundplane.pdfhttp://rudys.typepad.com/ant/files/antenna_vertical_groundplane.pdfhttp://www.antennasbyn6lf.com/http://www.antennasbyn6lf.com/http://rudys.typepad.com/ant/files/antenna_vertical_groundplane.pdfhttp://rudys.typepad.com/ant/files/antenna_vertical_groundplane.pdfhttp://www.yccc.org/Articles/double_l.htmhttp://www.cebik.com/vhat.htmlhttp://www.cebik.com/http://www.iol.ie/~bravo/80&40mVertic.htm


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As t he Capac i ty hat s get larger , the resonant length shor tens


4/14



In t he ar t ic le , Rudy m odels a t rad i t iona l fu l l s ize 80m 1/4

w /l w i th 4 e leva ted rad ia ls. He compares th is w i th anumber o f"H" antennae , w h ich vary from 30 f t t o 120f t in

he ight . For the fu l l s ize 1 /4 w /l ver t ic a l , he pred ic ts a

feed im pedance of 35.7 Ohms, a 2 :1 SWR bandw idth o f

175kHz, a peak (tak e o f f ) ang le o f 22 degrees, and a

gain o f + .21 dBi . Using h is tab les , my "H" d ipo le com es

up as hav ing a cen t re feed im pedance o f 45 Ohms, o r 65

Ohms i f fed a t t he bot tom . A 2:1 SWR bandw idth o f

170kHz, a peak angle o f 23 degrees, and ga in o f -- .25

dBi

You can see f rom t h is, t ha t m y 50 ft "H" has a lmos t

exac t l y t he same bandw id th and peak ang le as the fu l l

s ize 1 /4 w /l ver t ica l , and t he ga in is on ly dow n by .5 dB i ..

( Ver t ica l "H" Dipo le)
http://rudys.typepad.com/ant/files/antenna_vertical_loaded.pdfhttp://rudys.typepad.com/ant/files/antenna_vertical_loaded.pdf


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I have come to the c onc lusion f rom m y experiments ,

readings and observa t ions, t ha t a capac i t y ha t ted

ver t ica l d ipo le , a few feet over ground, is LESSCOMPROMISED th an a 1/4 w /l ver t ic al of t he sa me height

fed aga ins t a less than perfec t g round . Let ' s f ace i t ,

MOST amat eur 's ground sys tems are m ediocre a t bes t .

A lso, the d ipo le is eas ier and c heaper to r ig , and is tw o

dimens ional ..Very impor tant in my s i t uat ion, as I cannot

run out rad ia ls on my ne ighbours proper ty . Or, to quot e

W4RNL..

"Since on ly a hand fu ll o f hams can ever have

160-met er antennas h igh enough t o y ie ld a low

angle DX s igna l , more prac t ic a l are ver t ica l

ar rays such as yours . Ver t ica l d ipo les w i th hats

(or Tees) save a p le t hora o f w i re needed by

monopoles."

Tom W8J I in a m a i l t o the Topband re f lec to r on the

subjec t o f smal l ant enna ef f ic iency , sums i t up neat ly ....
http://w8ji.com/http://w8ji.com/


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"The mos t e f f i c ien t w ay to bu ild a sma l l antenna

is to use as m uch c apac i tance as possib le a t t he

an tenna ends , and t o keep t he h igh vo l tage

areas aw ay f rom ear th or lossy media .

I t i s a lw ays a tough p ro jec t t o bu i ld an e f f i c ien t

sma l l antenna , bu t t he bo t tom l ine i s you w ant

the h ighes t cu r rent over the la rgest s t ra igh t a rea

poss ib le and the open ends aw ay f rom th ingsthat might be lossy . Us ing h igh Q co i ls c an

ac tua l l y be much more e f f i c ient t han fo ld ing

w i res , but g ives less bandw idth . Capac i t ance

hats a t t he open ends alw ays he lp bandw id th

and ef f ic ienc y ."

Being t w o d imensional , I c an r ig the d ipoles a long my

fence l ine, and t h is leaves t he or ig ina l s i te , com pletew i th i t ' s g round sys tem , avai lable fo r t he use o f my

K9AY loops..

(Draw ing o f t he or ig ina l pai r o f phased 80m ver t i c a l d ipo les a tEI7BA)


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I 'm now using 45f t d ipo les . loaded top and bot t om (cap

hat w i res) on 80 and 160m, suspended f rom a 60 f t h ight imber mas t , as in t he d raw ing above.

I have done s ide by s ide compar isons w i th my Inver ted

L, and var ious 1 /4 w /l ver t ic a ls that I 've bu i l t . They

com pare very favourab ly indeed, w i th the ver t ica l d ipo le

usual l y a t ad be t t e r t han any o f m y 1 /4 w /l ve r t i ca ls both

on TX and RX. For som e reason, the d ipo les are qu ie ter

on RX than the o thers ...'dunno w hy...Not t hat i t ' s an

issue here , as I use a K9AY on RX w hen the go ing ge ts

tough. .

The d ipo les a re m uch qu icker t o e rec t , as t hey' re on ly 2d imens ional (no ground sys tem ). Mine are erec t ed a long

the fence be tw een tw o f ields on m y ne ighbour 's f a rm.

Be ing no w ider than t he fence i t se lf , t he an tennae do no t

in te r fe re w i th t he agr icu l tu ra l ac t i v i t i es in any w ay . Th is

means t ha t my fa rmer neighbour i s qu ite happy t o le t me

put up as much w i re as I l i ke . ..

( v iew to the Wes t )


8/14



Because I l i ve on the coas t , w e ge t s t rong w inds in the

Winter . To "s t ream l ine" the antenna, I now feed t he

d ipoles a t t he base o f t he ver t i ca l w i re .

IMPORTANT... Because the dipole is now fed

asymet r i ca l l y , w e mus t use a good choke ba lun a t t he

feedpo int . At t hese f requenc ies , w e mus t use a h igh

permeabi l i t y fer r i te c ore. I use a FT-240-61 c ore, w ound

w i th as many tu rns as poss ible o f RG58 coax ( I t h ink I

go t abou t 12 o r13 on m ine). Wind on abou t ha l f t he tu rns ,

then c ross to the oppos i te s ide o f t he c ore, and w ind in

the oppos i te d i rec t ion fo r t he rema in ing tu rns .


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I f you 've got any large fer r i te cores in your junk box, and

you don ' t have a c lue w hat permeabi l i t y they are, here 's

a qu ick check t ha t I use .

Wind tw o t igh t t u rns a round the c ore w i th insula ted

w i re .. Connec t t he ends t o the an tenna socke t o f your

Antenna Analyser (MFJ 259 e tc ) Swi t ch func t ion to read

induc t ance , and se t t he f requency t o somewhere

around1.8mHz.

I f t he meter reads any va lue o f induc tance , t hen t ha t

core i s p robab ly use fu l dow n as fa r as 160m. I a lso use

the same method t o check sma l l co res fo r use as 9 :1

t ra f fos for a Beverage, K9AY etc .

Here's a qu ick w ay to check a choke ba lun . I f f lopp ing

the cab le a round on the g round , or handl ing the bo t tom

end o f t he choke has no e f fec t on the SWR, then i t ' s

probably w ork ing e f fec t ive ly . I f t he SWR var ies w i th t h is

t reat ment , then i t ' s NOT w ork ing proper ly .

Rudy uses a d rum o f coax as a c hoke on h is 160m

array. .. .Overk i l l . .? perhaps. . b ut ef fect ive. .


10/14



On the comm erc ia l f ron t , Force 12 have s t i r red up qu i tea b i t o f in te rest w i th the i rSigma Ver t ic a l antennae. Th is

an tenna looks uncann i l y l i ke t he ver t i ca l d ipo les t ha t

W4RNL has had on h is w ebs i te for years . Take a look a t

w hat they have to say about ver t ic a l d ipo les ..

The ir 80m Sigma has a 36 f t ve r t i ca l sec t ion , has a

70kHz SWR bandw idth , and I 'm sure i t is an e f fec t ive

antenna. I f you 've got a handy 50f t or h igher t ree on your

proper ty , the w i re vers ion should cos t $50.00 or less ,

and w i th the h igher ve r t i ca l sec t ion shou ld be even m ore

ef fec t ive . .

The nex t mod if ica t i on t ha t I i n t end t o make t o my

Ver t ica l D ipo le, w i l l be t o fo l low LB 's suggest ion, and use

ext ra vert ic a l w i res spaced about 4-6 inc hes. Th is should

increase the bandw idth , and genera l e f f ic iency ( less

res is t ive losses) o f the antenna.
http://www.force12inc.com/31943/index.html?*session*id*key*=*session*id*val*http://www.force12inc.com/31943/index.html?*session*id*key*=*session*id*val*


11/14



My RX Ant enna..

"On the low bands , t he average amateur rece iver

has exc ess ga in , and so a low-ga in rece iv ing

antenna w i th a rear nu ll is benefic ia l . . Not on ly

does i t im prove the s igna l t o no ise ra t io andremove rearw ard QRM, but i t a lso reduces the

occ urrenc e of f ront -end-over load f rom QRM, QRN,

and f rom nearby AM BC s ta t ions in the MF

range. Hence, ga in must be ta i lo red to the

s i tua t ion--w h ich i s no t t he same on 160 as i t i s

on 20 met ers . Pat t ern shape--both hor izonta l ly

and ver t ic al ly (i .e., the w hole 3 -D pat t ern)--

becomes m ore impor tan t t han ga in i t se l f ."

The above quote f rom W4RNL is an ex ce l lent synops is o fthe requ i rement s for good Low Band RX per formance.

For an " in -depth" d iscuss ion on the top ic go t o Tom

W8JI 's w ebsi te and read h is Receiv ing sec t ion .

I do o f course, use my TX antennae on rece ive a lso. .

However , The s ing le mos t im portan t addi t ion t o my

DXing arm oury is def in i te ly my K 9AY loop ar ray ...

Gary Breed K9AY, d id us a l l a huge favour, w hen he

publ ished that famous a r t i c le in Septe mber 1997 QSTMagazine . I cou ld "w ax l y r ica l " about t he e f fec t i veness

o f t h is antenna , but I sha l l resis t t he tempt a t ion , as i t

has a l l been w e l l covered be fo re.. I w i l l j ust ment ion t ha t

the K9AY is one o f a number o f smal l and e f fec t i ve

rec eiv ing ant ennae, such as t he EWE, Flag, Pennant ,

K6STI e tc . that have bec ome very popular .

There i s a w ea l th o f in fo rmat ion to be found on t he

w eb abou t a l l o f t hese an tennae , on some real l yexce l len t w ebs ites .. Your f i r st v i si t shou ld be s t ra igh t t o

" the horse 's mouth " a t Gary Breed 's K9AY s i te . Ot her

si tes that you should v is i t inc lude Mark Connel ly

WA1ION , Tom W8J I , F lag and Pennant Antenna

Compendium , Hard Core DX , and Wel lbrook produc ts

t o men t i on bu t a f ew ..

I have made t w o phys ica l mod i f i ca t ions to the o r igina l

K9AY des ign..
http://w8ji.com/http://w8ji.com/http://w8ji.com/receiving.htmhttp://www.hard-core-dx.com/nordicdx/antenna/loop/k9ay/k9ay_orig.pdfhttp://www.aytechnologies.com/http://www.qsl.net/wa1ion/index.htmlhttp://www.qsl.net/wa1ion/index.htmlhttp://w8ji.com/receiving.htmhttp://www.angelfire.com/md/k3ky/page37.htmlhttp://www.angelfire.com/md/k3ky/page37.htmlhttp://www.hard-core-dx.com/nordicdx/antenna/loop/k9ay/k9ay14.htmlhttp://www.wellbrook.uk.com/products.htmlhttp://www.wellbrook.uk.com/products.htmlhttp://www.wellbrook.uk.com/products.htmlhttp://www.hard-core-dx.com/nordicdx/antenna/loop/k9ay/k9ay14.htmlhttp://www.angelfire.com/md/k3ky/page37.htmlhttp://www.angelfire.com/md/k3ky/page37.htmlhttp://w8ji.com/receiving.htmhttp://www.qsl.net/wa1ion/index.htmlhttp://www.qsl.net/wa1ion/index.htmlhttp://www.aytechnologies.com/http://www.hard-core-dx.com/nordicdx/antenna/loop/k9ay/k9ay_orig.pdfhttp://w8ji.com/receiving.htmhttp://w8ji.com/http://w8ji.com/


12/14



( Draw ing o f my K 9AY var ia t ion . .H igher bo t t om w i res = few erdecapi tat ions. . ! )

I have ra ised the bo t t om o f t he loops, t o a m ore

comfor tab le he ight f o r law nmow ing e tc .. and I have

added a fur ther tw o re lays to the Cont ro l box . These

re lays sw i t ch in ex t ra resis to rs in para lle l w i th the ma in

term inat ing resis tor . Th is a l low s me t o have opt im um


13/14



va lues fo r bo th 80 and 160m, w i thou t t he c omplex i t y o f

cont ro l l i ng a Vac t ro l .

PERFORMANCE...

Jus t t w o examp les o f my expe r iences w i t h

my K9AY..

The 10t h August 2000. . FR/F6KDF/T on 1.824mHz.

Tromele in Is land DXpedi t ion. QRN S9 on t he TX ver t ica l .

EU QRM almost c runch ing t he f ront end on my

FT1000MP.. Absolu te ly no c opy on the DX at m y end. On

sw i tc h ing to the K 9AY Loop, the QRN dropped t o perhaps

S5. With t he nul l po int ing at EU, FR/F6KDF/T i s now

readable.

I w orked h im, in sp i te o f t he c ompet i t i on f rom the EU"b ig guns" 5 5 9 bo t h w ays.

I 'm no t a con tes te r , bu t I do l i ke to g ive ou t as

many " mu l t s " as I can on t he Low Bands . Wi th t he EUs in

fu l l c ry , i t ' s very hard t o copy Stat es ide on the TX

antenna w hen t he QRM is way over S9. On sw i tc h ing to

the K9AY t he no ise leve l d rops d ramat ica l l y, t he s igna ls

a lso drop a few S po in ts , but w i th t he ex t ra 20/30dB nu l l

now point ing a t Europe, the Stat es ide s ta t ions , a l though

w eaker , are now "armc hai r copy" .

Impor tan t No te ..

I do no t ment ion Beverages, 4 square a r rays etc on t h is

page, as i t ' s a imed a t t he Amateur w ho has no possib i li t y

o f e rec t ing such la rge an tennae.. I hope t ha t i t m ay g ive

some encouragement to t hose w ho ( l ike myse l f) have

l imi t ed space and resources.

Home Links Contac t In forma t i on

Copyr igh t 1995 - 2008 John Tai t Al l r igh ts reserved.

A l l pages and content there- in , are the in te l lec tua l p roper ty o f the au thor , and pro tec ted by law.

A l l pages and content , a re sub jec t to change a t any t ime, w i t hout no t ice .
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antennas for the low bands..80 and 160m

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