Nghiên cứu, chế tạo phân tử thụ động, cấu kiện và ănten siêu cao tần dùng công nghệ mạch dải

DAI HOC QUOC GIA HA NOI
oOo"
--

NGHIEN CUU, CH^ TAO PHAN

T U THU OONG, CAU KI£N VA
ANTEN SIEU C A O TAN D U N G CONG NGHE MACH DAI

(Bao cao tong hop de tai nghien ciru khoa hoc do khoa quan ly cSp DHQGHN )

Ma so QC-03-01
Chti nhiem de tai: GS.TSKH Phan Anh

HA NOI-2005


Bdo cdo tSng hap di tai NCKH cSp DHQGHl

MUC LUC
•

DANH SACH

NHONG

•

NGLfClI THAM GIA THl/C HIEN DE TAI

TOM T A T N H 0 " N G K E T Q U A C H I N H C U A BE

TAI

DANH MUC CAC HINH
Phan I: G i m THIEU CHUNG
I.

Dat van de

II.
III.

Tong quan cac van de nghien ctru ciia de tai
E)ia diem, thai gian va phuang phap nghien ciru

PhSn II: NOI DUNG VA KET QUA NGHIEN CtTU
Chu-ang I: (Nguyen ly thiet ke angten mach dai
I.
II.
///.

Cau lao va nguyen ly boat dgng cua angten mach dai
Phuang phap phan tich anten mach dai
Tbiet ke va mo pbong anten mach dai hinh cbir nhat

Chuang 11: Ihiet ke che tao cac linh kien thu dong sieu cao tan
I.

Gioi thieu

II.
III.
IV.
V.

Nghien cuu ly tbuyet sieu cao tan
Nghien cuu thiet ke va che tao
Do dac hieu chinh
Nghien cuu phat trien

Chvoiig III: Thiet ke bo khuech dai sieu cao tan cong suat nho
I.

Cac buoc can thuc hien khi thiet ke:

II.
III.

Cac phuang phap each ly cao tlin trong thiet ke bg khuech dai sieu cao tSn:
Phoi hop tra khang tai loi vao va loi ra cua bo khuech dai

TAI LIEU THAM

KHAO

PHU LUC:
Phu luc A: Hinh anh minh hoa cac san pham da hoan thanh
Phu luc B: Cac bai bao
Phu luc C: Cac bao cao khoa hoc, luan vin, luan an
PHIEU DANG KY KET QUA NGHIEN CUtJ

Bdo cdo tSng hap di tai NCKH cdp DHQGHN

MUC LUC
•

DANH SACH
TOM T A T

NHUNG

NHUNG

•

NGl/C^I THAM GIA THL/C HIEN DE TAI

KET QUA CHINH CUA DE TAI

DANH MUC CAC HINH
PhSn I: GlOfl THIEU CHUNG
I.
II.

Dat van de
Tong quan cac van de nghien ciru ciia de tai

III.

Dia diem, thai gian va phuang phap nghien ciru

Phan H: NOI DUNG VA KET QUA NGHIEN ClTU
Chu'o'ng I: Nguyen ly thiet ke angten mach dai
I.
II.

Cau tao va nguyen ly boat dgng ciia angten mach dai
Phuong phap phan tich anten mach dai

///.

rhiet ke va mo phong anten mach dai hinh chir nhat

Chucng 11: I hiet ke che tao cac linh kien thu dong sieu cao tan
I.

Gioi thieu

II.
III.
IV.
V.

Nghien cuu ly thuyet sieu cao tan
Nghien ciru thiet ke va che tao
Do dac hieu chinh
Nghien cuu phat trien

Chirong III: Thiet ke bg khuech dai sieu cao tan cong suat nho

I.
II.

Cac buoc can thuc hien khi thiet ke:
Cac phuang phap each ly cao tan trong thiet ke bg khuech dai sieu cao tan;

III.

Phoi hop tra khang tai loi vao va loi ra cua bg khuech dai

TAI LIEU THAM KHAO
PHU LUC:
Phu luc A: Hinh anh minh hoa cac san pham da hoan thanh
Phu luc B: Cac bai bao
Phu luc C: Cac bao cao khoa hoc, luan van, luan an
PHIEU DANG KY KET QUA NGHIEN CUtJ


Bdo cdo tSng hap di tai NCKH cap DHQGHN

DANH SACH NHLfNG NGLfOI THAM GIA THUC HiEN O^ TAI

1. GS. TSKH Phan Anh
2. PGS. Nguyen Khang Cuong
3. CN. LeQuang Toan
4. CN. Tr4n Thi Thuy Quynh
5. CN. Tran Nggc Hung
6. CN. Duang Thi Quynh Thu
X

/

7. CN. Tran Anh Tuan


Bdo cdo tSng hap di tdi NCKH cSp BHQGHN

DANH MUC CAC HINH
Hinh 1: Cau true ca ban cua mot angten mach dai
Hinh 2: Nguyen ly boat dgng cua angten mach dai
Hinh 3: Ky thuat tiep dien bang mach dai
Hinh 4: Phan c\ic thang
Hinh 5: Cac cau true phan cue tron
Hinh 6: Mat cal cua phan tu hinh chu nhat vai nguon buc xa trong mat phang E.
Hinh 7: Tinh tra khang vao cua angten Vi buac song
Hinh 8: Sa do fnach tuang duang tinh tra khang vao cua angten ^4 buac song
Hinh 9: Angten bang hep hinh chii nhat
Hinh 10. Dap ung bieii dg-tan so ciia bg khuech dai
Hinh 11. Cau true va phan bo dien tu ciia duong truyen mach dai
Hinh 12. Sa do tuong duang cua mot doan mach dai c6 chieu dai nho ban
Hinh 13. Sa do khoi ciia mot bg khuech dai cao tan
Hinh 14. Phoi hgp tra khang bang mot doan day chem.

A /
y^


Bdo cdo tdng hap di tdi NCKH cdp BHQGHN

TOM TAT

N H O N G K^T QUA

CHINH CUA O^ TAI

1. Ten de tai:

Nghien cuu, che tao phan tu thu dgng. cau kien va angten sieu cao tan dung cong
nyhe rnach dai.
t—'

•

•

Mas6:(X>03-01
2. Chu tri 6e tai: GS.TSKH. Phan Anh
Dia chi :

Truong Dai Hgc C orig Nghe, Dai hoc Quoc Gia Ha Ngi
144 Xuan Thuy, Cau Giay, Ha Ngi

Dienthoai: 04.7549270
3. Nhirng ket qua chinh:
a. Kit qua ve khoa hoc (cac bai bao va bao cao khoa hgc da cong bo):
''Study and design of a Compaci High-gain Broadband Circular Polarization
Array foi' IVLAN operations". Tran ngoc Hung, Phan Anh, Hoi nghi v6 tuyen
dien tir loan quoc Ian thu 9(11 /2004).
^'Analysis of the impact of lumped Components worked into the coupled
congruent line Filter on its performance", Tran Anli Tuan, Phan Anh , Hoi

nghi v6 tuyen dien tij toan quoc [an thii 9 (11/2004).
-

^'Microwave phase shifter using hybrid combined varactor diode'\ Tran Thi
Thuy Quynh, Phan Anh, Hoi nghi v6 tuyen dien tti toan quoc Ian thu 9
(11/2004).

-

''Some study on Scattering Properties of Travelling-Wave Excitation of
Cavity-Backed Arbitrary Narrow Slot Structures by Moment Method'\ Phan
Anh, Tran Minh Tuan, Hoi nghi v6 tuyen dien tu toan quoc Ian thu

9

(11/2004).
-

'Thiet ke anten mach dai phan cue trdn dung trong cac he thong WLAN'\
Trin Ngoc Hung, Hoi nghj NCKH 2004, Truong DHCN.


Bdo cdo tdng hap di tdi NCKH cSp DHQGHN
-

"Techniques of Widening B andwidth of Coupled Line Filter Using Lumped
Components", Tran Anh Tuan. Phan Anh, The 6^'' MINT Milimetter-Wave
International Symposium, The 7'^' Topical Symposium on Millimeter Waves,
February 24-25/2005, Sofitel Ambassador Seoul, Seoul, Korea.

b. Kit qudphuc vu thuc ti :
Cac san pham da dat dugc:
+ Ve anten sieu cao tan dung cong nghe mach dai:
- Angten mach dai phan cue thang: Nghien cuu ly thuyet thiet ke tong quat (cau
true, cac phuang phap ma rgng dai tan...), Thiet ke, mo phong va che tao
thanh cong 2 mau angten dai rgng boat dgng tai tan so trung tarn 2.45 GHz , da
dugc kiem chung bang each do dac thu nghiem.
- Angten p han c uc tron: Xaydimg cac mau anten tren phan mem mo phong
ANSOFT. Hoan thanh 2 mau angten mach dai phan cue tron, tan so 2.5 GHz.
Da do dac va thu nghiem thanh cong trong cac he thu phat WL.AN.
\

r

^

^

+ Ve cac cau kien va cac phan tu sieu cao tan
- Khuech dai cong suat: Nghien cim ly thuyet thiet ke bg khuech dai cong suat
tuyen tinh (lop A, AB), mot so ky thuat bu meo trong thiet ke bg khuech dai
cong suat; che tao thii nghiem rngt rriau khuech dai cong suat (Pin=lmW,
Pout=4W).
- Bg chia cong suat: Nghien cuu ly thuyet thiet ke, thuc hien 2 mau thiet ke (bg
chia 2 va bg chia 4)
- Cac bg Igc: Nghien cuu ly thuyet va thiet ke LPF, BPF UHF/VHF dung cong
nghe mach vi dai
- Mach Hybrid: Nghien cuu ly thuyet ve nguyen ly, each xay dung cac mach
Hybrid. Che tao thanh cong mot mach Hybrid boat dgng tai tan so 2.5 GHz,
suy giam moi cong 3dB.

- Bg cong cong suat: Tim hieu nguyen ly, che tao thanh cong 2 bg ghep cong
suat CO tan so hoat dgng 700 MHz, 4 cong va 2 cong.


Bdo cdo tdng hap de tdi NCKH cSp BHQGHN
- B6 tao dao dgng sieu cao tan:
c. Kit qua dao tao:
+ Hai giai nhi ciia sinh vien va hgc vien NCKH 2003:
- De tai: " Thiet ke bg Igc thong rbap boat dgng a dai viba. co dap ung bien do
gan ly tuong"
- De tai; '7hiet ke che tao bg Igc itiong thap dai tan 850 MHz'"
+ Giai ba sinh vien NCKH 2003:
- De tai: 'Nghien cuu, thiet ke va cbe tao bg khuech dai sieu cao tan dung cong
nghe mach dai"
+ Hai khoa iuan tot nghiep 2003:
- D6 tai: "Nghien cuu, thiSt k§ va che tao bg khuech dai sieu cao tan dung cong
nghe mach dai", bao ve thang 5/2003.
- D6 tai: ^"Ihi^t kl chS tao bg Igi thong th4p dai \kn 850 MHz'\, bao ve thang
5/2003
+ Mot luan van thac sy, bao ve thang 1/2005:
- De tai: "Nghien cuu, mo phong va thiet ke he dieu khien bup song cho angten
mang pha".
d. Ket qua nang cao tiem lite khoa hgc (nang cao trinh do can bg va tang cuong
trang thiet bi cho don vi):
De tai da dong gop rat nhieu cho cong tac dao tao sinh vien va hgc vien cao hgc
cua khoa, ddng thai ciing nang cao trinh do chuyen mon cho cac can bg tham gia
thuc hien. Ngoai ra mot s6 trang thiet bi cung dugc tang cuong tu kinh phi ho trg
cua de tai, gom c6:
- Mot so vat tu, linh kien sieu cao tan
- Cac tai lieu khoa hgc (sach, tap chi...) trong va ngoai nuoc

e. Tinh hinh sir dung kinh phi:


Bdo cdo tdng hap di tdi NCKH cdp BHQGHN
Da su dung net kinh phi dugc cap (40 trieu dong)
-H Giai trinh nhirng khoan chi Ion:
- Thue khoan chuyen mon: 15 trieu dong
-

Mua nguyen vat lieu, dung cu thi nghiem va tai lieu: 20 trieu dong

- Chi phi khac: 5 trieu dong


Bdo cdo tdng hap di tdi NCKH cdp DHQGHN

Phlin I: GIOI THIEU CHUNG

L DAT VAN DE;
>

'

'

Hien nay, cac thiet bi sieu cao tan dang dugc sir dung bet sue rgng rai trong rat
nhieu ITnh vuc. dac biet la ITnh vuc truyen thong. Cac phan tu linh kien sieu cao tan
dugc ung dung a xki nhi^u khau trong he thong thong tin v6 tuyen. Dong thai thong
tin v6 tuySn cung la phuang lien de phai trien he thong thong tin hien dai, vi du:
thong tin di dong. thong tin chuyen tiep trong mang vien thong hay thong tin truyen

dii lieu trong mang may tinh...
Trong xu the do, viec nghien cuu va che tao cac phan tu thu dgng va cac cau kien
sieu cao tan la nhung rihu c^u \k ySu va dang dugc tien hanh rgng khap tren the
giai. Yeu cau ve tinh nho gon, linh dong ciia cac thiet bi cung la mot yeu to dang
quan tarn. Cong nghe mach dai ra doi dap ung dugc nhu cau doi hoi nay. Viec che
tao cac ph^n tu. c4u kien sieu cao tan hau nhu bat buoc phai dung den cong nghe
mach dai.
D§ tai "'Nghien ciru, chi tao phdn tu thu dong, cau kien vd angten sieu cao tan dung
cong nghe mach dai" tap trung vao viec nghien cuu va che tao cac phan tu ang ten
va c§u kien sieu cao tan dung cong nghe mach dai, vai muc tieu la phat trien thong
tin v6 tuyen a dai song sieu cao tin. Day cung la mot huang nghien cuu cua bo mon
Thong tin V6 tuySn, khoa Dien tu Vien thong.

n. TONG QUAN CAC V A N DE NGHIEN ClTU CUA DE TAI
De tai tap trung nghien cuu theo hai mang chinh:
- Nghien cim, thilt ke cac loai anten mach dai, gom c6 ang ten phan cue thang
va phan cue tron, c6 do tang ich va dinh huang cao. Dai tan lam viec trong
khoang 2.4-2.5 GHz, phu hap cho cac bo thu phat trong cac he Wireless LAN.
- Nghien cuu, thilt k8 cau kien va cac phan tu sieu cao tan de tu do c6 the xay
dimg mot he thdng thu phat sieu cao tan hoan chinh, phuc vu cho muc dich
giang day, nghien cuu va ung dung trong thuc tien. Cac noi dung bao gom:
8

t


Bdo cdo tdng hap di tdi NCKH cdp BHQGHN
+ Cac bo igc sieu cao tan
+ Bg khuyech dai cong suat
+ Bg chia cong suat

+ Cac bg cong cong su4t
+ Mach Hybrid
+ Bg tao dao dgng sieu cao tan

in. DIA DIEM, THOI GIAN VA PHUONG PHAP NGHIEN CUl^
• De tai dugc thuc hien tai Trung tam nghien cuu Dien tu - Vien thong, truong
Dai Hgc Cong Nghe, DHQG Ha Ngi trong thai gian la 1 nam.
• Phuang phap nghien cuu ciia de tai la nghien cuu ly tbuyet ket hgp voi thuc
nghiem. Tren co so cac nguyen ly ve cong nghe mach dai va sieu cao tan, su
^

^

I

f

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•)

dung cac phan mem chuyen dung de thiet ke, xay dung neri cac mau san pham
va danh gia ket qua qua mo hinh mo phong. Tu cac mau mo phong toi uu nhat
se dugc che tao thanh cac mau san pham, cac san pham nay sau do dugc do
dac kiem nghiem lai bang cac thiet bi do luong trong dieu kien thuc te.
De tai co sir dung co so vat chat cua Trung tam nghien cuu Dien tu - Vien thong:
f

1

Cac thiet bi do luong nhu may phan tich mang, may phan tich pho..., may phay
mach in va cac phan mejn thiet ke, mo phong. Ngoai ra con su dung mot so loai may
moc cua cac bg mon khac va cac co quan ben ngoai Dai hgc Quoc Gia.


Bdo cdo tdng hap di tdi NCKH cdp DHQGHN

Phin II: NOI DUNG VA K^T QUA NGHIEN CUU

ChiFcng I: Nguyen ly thi§t ke angten mach dai
f

I. Cau tao va nguyen ly hoat dong cua angten mach dai
Ang ten mach dai (microstrip antenna) la loai anten c6 kich thuoc ggn nhe,
mong va co do chac chan cao. Thuc chat day la mot ket cau buc xa kieu khe. Nhijng
uu diem cua angten mach dai gom co; gia thanh thap, tinh tuong thich cao, khoi
lugng va kich thuoc nho, bao gom ca angien phan cue thang va angten phan cue
/

f

-

tron. Cac dac tinh nay la rat quy gia khi xem xet angten cho cac he thong WLAN.
Thuc chat angten mach dai la mot tam buc xa ve mot phia ciia lap dien moi
voi mot mat phang dat a phia duai. Moi phan tu angten gom cac thanh phan: phien
r

/

'

f

kim loai, lap de dien moi va man chan kim loai dong vai tro la dat. Phien kim loai
dugc gan len tren lop de dien moi tao nen rngt ket cau tuong tu nhu ban mach in (vi
f

the anten macli dai con dugc ggi la anten mach in).
Radiating Crndijr'nr

Dielectric Substrate

Ground Plane

Hinh 1: Cau true ca ban cua mot angten mach dai
Cac thong so cau true ca ban cua mot phan tu anten mach dai bao gom: chieu
dai L, chieu rgng W, do day h va hang so dien moi SrCiia lop de dien moi. Tuy thuoc
vao gia tri cac thong so dugc lira chgn ta se co cac loai anten khac nhau. Hang so
f

*

dien moi dong vai tro quan trong nhat vai hoat dgng ciia angten. No anh huang den
"
"
10

Bdo cdo tdng hap di tdi NCKH cdp DHQGHN
do rgng, theo dc la tra khang dac tinh; chieu dai, theo do la tan so cong huong
hieu suat buc xa ciia angten mach dai.

vkr^
J ^

1.1. Nguyen ly hoat dong cua angten mach dai:
Song dien tu fring off tir tam phia tren vao trong lap dien moi, sau do phan xa
tren mat phang dat va buc xa vao khong gian phia tren. Truong buc xa xay ra chu
yeu do truong giua tam phang phia tren va mat phang dat.-

Hinh 2: Nguyen ly hoat dong ciia angten mach dai
r

f

\

f

Hieu suat buc xa cua angten mach dai phu thuoc rat Ian vao hang so dien moi
8r. Theo ly thuyet, lap dien moi day vai hang so dien mo[jhap va mat mat ton bao

^

nho se mo rgng bang tan va nang cao hieu suat truyen.
+ Cac cau true tiep dien cho an^n mach dai:
f

•p

f

De angten tao ra truong buc xa a phia tren tam kim loai ta phai tiep dien cho
phien kim loai boat dgng. Cau true cua truong buc xa tuy thuoc vao cac ky thuat tiep
f

t

r

f

f

dien cho anten. Co ba cau true pho bien nhat thuong dugc su dung, do la tiep dien
>

>

>

\-

f

>

bang cap dong true, tiep dien bang mach dai va tiep dien cong huang.
f

\

\

r^

+ Vai each tiep dien bang cap dong true, day dan dien ben trong cap se dugc
gan voi tam phang kim loai phia tren, con v6 cap noi vai mat phan/dat phia duai.
Cau true tiep dien nay thuong dugc su dung vi de thuc hien phoi hgp tro khang vai
^

f

angten. Cung voi do, buc xa ciia feeder ciing khong anh huang nhieu den dac trung
buc xa ciia angten.

11

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Bdo cdo tdng hap di tdi NCKH cap DHQGHN
f

f

y

»

+ Cac cau true tiep dien bang duong truyen mach dai thong dung han tiep
dien bang cap dong true do de che tao va gia thanh thSp. No la mot duong truySn
dugc che tao theo cong nghe mach in gan lien vai phien kim loai. Nhugc di§m cua
cau triic nay la anh huong do truong buc xa ciia feeder ddn dac trung buc xa ciia
angten.
+ Cau tnic tiep dien cong huang co day dii cac uu diem cua hai cau triic tren,
f

>

dong thai each ly tam buc xa vai feeder. Tuy nhien ky thuat nay chi dugc ap dung
trong mot so cac truong hgp dac biet, khi ma co nhieu ban mot lap dien moi a giiJa.
paten

Hinh 3: Ky thuat tiep dien bang mach dai

1.2. Cac kieu phan cijc
Day la phan cue cua song buc xa bai angten theo mot huong nhat dinh, no
f

,

thuong phu thuoc vao ky thuat tiep diem Tuy theo muc dich sir dung ma ta co the tao
ra cac truong buc xa phan cue thang hoac phan cue tron bang each su dung cac bien
phap thich hgp.
Phan cijrc thang:
Theo cac phuong phap tiep dien thong thuong thi truong phan cue ciia angten

mach dai la truong phan cue thang. Angten khe la mot dang don gian nhat ciia
t

f

angten phan cue thang. Tren mot chiec angten khe, truong E huong vuong goc voi
chieu dai ciia no. Hinh 4 minh hoa hoat dgng ciia song phan cue thang vuong goc
vai mat phang buc xa

12


Bdo cdo tdng hap di tdi NCKH cdp BHQGHN

Hinh 4: Phdn cue thang
Phan cue tron:
Phan cue tron (Circular Polarization - CP) thuong dugc tao ra bang each tiep
dien vuong goc vai nhau. Ngoai ra nguai ta co the su dung phuang phap cat hai goc
f

y

doi dien nhu hinh minh hoa duai day. Khi hai tin hieu co bien do bang nhau nhung
lech pha 90' thi song tong hgp se co dang phan cue tron. Cac dang phan cue tron
bao gom phan cue tron trai (LHCP) khi ma song quay ngugc chieu kim dong ho va
phan cue tron phai (RHCP) khi song quay cung chieu kim dong ho. Uu diem chinh
f

t

•,

ciia phan cue tron la bat ke angten thu dat theo huang nao no cijng co the thu dugc
X

X

f

i

t

mot thanh phan ciia tin hieu. Dieu do la do song tai co goc quay bien doi. Kieu anien
phan cue tron thuong dugc su dung trong cac he WLAN o moi truong truyen song
phuc tap (indoor).
truncated
conners-

feed line

13


Bdo cdo tdng hap di tdi NCKH cdp BHQGHN

\\x
IN"("'j*j;m

1/

HCP R l l t r

Hinh 5: Cac cau true phdn cue trdn
II. Phu'ang phap phan tich anten mach dai
>^

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Angten mach dai dugc cau tao nhu cong nghe mach in. Khi hang so dien moi
£r la xac dinh, truong buc xa ciia no phu thuoc vao ket cau ciia angten, cu the la phu
thuoc vao tam kim loai phia tren lop dien moi. Do do, tuy thuoc vao timg loai anten
ma CO phuang phap phan tich khacnhau. Duai day la hai phuang phap thuong dugc
su dung pho bien nhat:
• Phuang phap duang truyen dan (transmission line method): Dugc su dung
cho cac phien kim loai co hinh dang don gian, chang han nhu hinh chir nhat,
hinh tam giac, hinh tron...
/

f

• Phuang phap hoc cong huong: Su dung khi cac phien kim loai co hinh dang
phuc tap.
+ Phan tich angten mach dai hinh chCF nhat:

Theo phuang phap duong truyen dan, mot phan tu angten hinh chu nhat c6
the dugc mo ta tuong ducmg voi hai khe buc xa song song, chieu dai moi khe la W
dat each nhau mot khoang L. Moi khe buc xa dugc coi nhu mot dipol tu
Cac gian do huong ciia anten mach dai co the tinh toan dugc mot each kha
f

\

chinh xac. Chia khoa ciia viec tinh toan nay la thuc te cac nguon phat xa la truong
f

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t

dien buc xa qua cac ke ha nho tao ra do cac canh ciia nguyen to va mat dat phang
iti

t

\

f

phia duai. Moi khe do do phat xa dang huong trong niia mat cau phai tren mat dat

14


Bdo cdo tdng hap de tdi NCKH cap DHQGHN

f

'

y

phang. Hinh ve duai day chi ra mot mat cat ciia phan tu angten mach dai hinh chii
nhat vai nguon buc xa trong mat phSng h.

^

i—L
^

Hinh 6: Mat cat cua phdn tu hinh chir nhat vai nguon buc xa trong mat phang E.
+ Tro' khang vao cua angten
t

Tra khang vao cua anlen mach dai hinh chu nhat Vi buac song co the dugc
tinh tu mach tuong duong trong hinh 12:
Xd
2
•-L =

£

X

.'.,.<,

X

Y

Zn =

377t

Hinh 7: Tinh tra khang vao cua angten VJ buoc song
Tra khang buc xa cua moi khe xac dinh theo cong thuc:
RR-120?.O/W

1

(2.4)

Khi ph4n tu g6m 2 khe phat xa song song, tra khang vao se la:
Rin = 60AoAV

(2.5)

Dien nap (susceptance) cua cac khe kk hap tai tan so cong huong la^nguyen
nhan thu gon do dai cua anten tren thuc t§ nho han V2 buac song, tuc la L = 0.49?id

15


Bdo cdo tdng hap di tdi NCKH cdp DHQGHN
Tro khang vao c6 the phoi hgp 50Q bang each su dung mot trong 2 ky thuat.
Doi vai cac phan tu lam viec doc lap. tiep dien bang cac connector dong true, tro

khang 50Q co the dat dugc bang each dieu chinh khoang each I tir canh ciia phan tu
den diem tiep dien, nhu hinh ve. Nho rang tra khang phai bang 0 tai tam ciia phan
tu, thinh thoang nguoi ta Igi dung dieu nay de de dat cac dinh tan hoac lap ma.. .qua
cac 16 tai tam angten, vi no gay nen hieu ung khong dang ke tren mau va chi lam
thay doi nho tan so cong huong. Trong cac he angten mang gom nhieu phan tu,
nguon dugc cap tai canh va bg chuyen doi % buac song dugc su dung de chuyen doi
r

f

'

tro khang loi vao thanh bat ky muc nao ma ta mong muon.
Angten '/4 buac song co tra khang loi vao gap doi phan tu '/2 buac song. Tra
khang vao co the dugc tinh toan tu mach tuang duang va cong thuc thu dugc la
Z,n=RR=120Xo/W.
^0

^

w

>v-

>

SHORT
CIRCUIT

R.^

o

Xd.
4

Hinh 8: So do mach tuang duang tinh tra khang vao cua angten 'A buac song
Vai cac phan tu V^ buac song, do rgng nua buac song, tra khang vao la 240Q.
Gia tri nay kha cao, va ty s6 song dung dien ap VSWR 5:1 xay ra khi connector 50
Q dugc n6i true tiep vao canh cua ph4n tu. Do do diem tiep dien phai dat each canh

mot khoang 1 nhu hinh ve/Tra khang vao ciia phan tu % buac song dugc phoi hgp j 0
bang each sii dung bg chuyin d6i V* buac song nhu da noi a tren.
III. Thiet ke va mo phong anten mach dai hinh chO' nhat
Muc dich ciia viec thiSt k§ va mo phong mot anten mach dai bang hep hinh
f

t

chu nhat la d§ tim hi^u ky ve nguyen ly va quy trinh che tao angten phang. Dua tren
do ta CO thi thiat k§ cac loai angten bang rgng hom. Angten nay hoat dgng a tan so
2.45GHz vai tra khang vao 50 Ohms, su dung lap dien moi bakelite.
16


Bdo cdo tdng hap di tdi NCKH cdp DHQGHN
+ Tinh toan cac kich thLPoc:
dL
5

•il.

— —^

^

^

i

uenglh

-

-i-—

f

-A

Fringing
Field

Feed Location

Width :

t

/-^

^

Hinh 9: Angten bang hep hinh chit nhat
+ Chieu dai
r

*

t

\

f

Chieu dai cua tam phang xac dinh tan so cong huong, do vay no la mot tham
so rat quan trgng trong viec thiet ke cac loai angten bang hep. Do dai cua tam phang
dugc tinh toan tu phuang trinh duai day:
L= —

C

2/.V' e/r
\

f

(3.1)

-2dL
f

^

t

Voi nhiing tan so duai 2GHz, bien thien cua L theo h la khong dang ke. Day
f

\

r

la mot su xap xi hgp ly, chung nao tan so cong huong (f^) con nho hon 2GHz. Dai
lugng dL la chieu dai -ma rgng do truong a vung bao va co the dugc tinh theo
phuang trinh:
(3.2)

dL = 0A\2h
(e,^-0.2586)(PF/A + 0.8)
t

r

f

Co the xap xi dL theo mot so cong thuc khac, tuy vay phuong trinh (3.2) cho
f

f

f

f

\

f

ket qua tot nhat. Ket hgp (3.1) va (3.2) ta tinh dugc chieu dai 29.6mm cho mot tam
phang.
OAI HOC QUOC GIA HA NO.

or/ 3G4
17


Bdo cdo tdng hap di tdi NCKH cdp BHQGHN
+ Do rong:
Do rgng la mot tham so quyet dinh hieu suat, tro khang angten va do rgng
bang. No phu thuoc nhieu vao tan so boat dgng va hang so dien moi. Phuang trinh
duai day dugc su dung de tinh do rgng ciia tarn phang:
W-—-(^^^)-'^
2f. 2

(3.3)

Do rgng tinh dugc theo ly thuyet la 37.86mm

+ Tinh toa do diem tiep dien bang cap dong true
Sir dung phuang trinh dua ra trong Bahl/Bhartia [1] chiing ta co the tinh dugc

toa do cua diem tiep dien, cho phep tao ra tro khang phoi hgp 50 Ohms vai feeder.
Sir ph6i hgp tra khang t6t se lam tang do rgng bang, giam mat mat phan xa va nang
cao hieu suat ciia angten do no loai tru dugc nhung modes buc xa khong mong
mu6n. Toa do cua diem tiep dien co the dugc tinh theo cong thuc duai day:
W

y\ [ along the width) - —

(6)

XAalongthelength) = -jL^where^Jl)
24Un

= ^^^^^{\'^\2-^^^^^^
2
2
L

(7)

Toa do diem tiep dien tinh toan dugc cho tam phang hinh chu nhat boat dgng
6 t4n so 2.45GHz la Yf = 7.52mm va Xf = 18.79mm. Tuy vay, viec tinh toan toa do
dau tiep dien theo cong thuc nay chi la buac dau. Can phai c6 mot qua trinh hoi quy
di tinh toan phoi hop tro khang feeder vai angten. Su dung may phan tich mang de
do dac, ta se thay toa do ciia dau tiep dien tot nhat la Yf = 7.00mm, Xf = 20mm, liic
ay tra khang vao dat dugc 49.85-0.012j Ohms.
f

f

^

^

\

Sau khi xac dinh dugc cac thong so ta tien hanh mo phong bang phan mem.

18


Bdo cdo tdng hap di tdi NCKH cap DHQGHN

Chu'O'ng II:
Thie* k§ ch§ tao cac linh kien thu dong sieu cao tan

I. Gioi thieu:
»

^

••

f

f

Cac pban tu thu dgng sieu cao tan la cac phan tu khong the thieu trong bat ki
f

/

^

'

cac he thong thong tin v6 tuyen nao. Cac phan tii do bao gom bg Igc, bg chia ghep
cong suat, cac bg cong huang, bg Hybrid v..v. Nen viec nghien cuu va cai tien chat
lugng ciia cac phan tu nay dang dugc nhieu nha nghien cuu va ky su quan tam. So
f

f

f

lugng cac cong trinh ve viec nghien cuu che tao cac loai thiet bi nay dugc cong bo
•rat nhieu tren cac tap chi khoa hgc noi tieng nhu IEEE transaction hay cac hoi nghi
/

t

>

f

quoc te.
7^

I

f

f

f

f

\

O Viet nam. hien tai nganh nghien cuu thiet ke che tao con rat yeu kem vi nhieu ly
»

^

f

do, dac biet la trong ITnh vuc sieu cao tan. Boi vi cac chi phi ve thiet bi va cong cu
f

•SI

f

f

y

ho trg cho viec nghien cuu che tao la rat dat, dong thai day cQng la mot ITnh vuc
chuyen mon kho, doi hoi cac nha nghien cuu phai co quyet tam cao va ^ay me voi

cong viec ciia minh.
Hien nay, do dugc su ho trg va dau tu rat Ion ciia nha nuoc va truong DHQG,
chiing toi, nhung nguoi dang lam viec tai Trung tam nghien cuu DHQG da co co hoi
ti§p can vai cac thiet bi do dac dat tien thuoc vS^ac de tai nghien cuu tugc ve nganh
cong nghe cao va c6n moi m^jjnhu cong nghe sieu cao tan.
Trong viec tiep can cong nghe, chiing toi bat dau tir viec khao sat va nghien cuu ly
f

y

•»

f

'

thuyet sieu cao tan, cac thiet bi do dac, cac loai vat lieu sieu cao tan, cac loai thiet bi
f

\

f

f

thu dgng sieu cao tan, cac phuong phap thiet ke che tao cac loai linh kien do, sau do
f

f

9

^

'

tien hanh che tao cac thiet bi theo cac phuang phap truyen thong . Sau khi da dat
f

f

'

'

dugc mot so thanh cong, chiing toi tien hanh viec cai tien chat lugng boat ciia cac
f

t

f

thiet bi va tim ra cac phuang phap mai de che tao chung. Muc tieu cua chiing toi la
tao ra cac thiSt bj co chat lugng hoat dgng tot, gia thanh re va kich thuac nho ggn.

II. Nghien CLPU ly thuyet sieu cao tan
19

^

Bdo cdo tdng hap de tdi NCKH cdp DHQGHN
f

\

r

y

*

•*

Trong ly thuyet sieu cao tan, van de co ban can dugc nghien cuu la ly thuyet
duang day truyen song. Bai vi tai tan so cao,

buac song truyen trong duong day

truyen s6ng co chieu dai nho, tuang duong voi kich thuoc ciia cac linh kien va cac
f

\

duong day noi trong mach dien tu. Han nua song truyen trong duong day bj anh
huong rat nhieu boi vat lieu che tao duong day do. Nen khi nghien cuu ly thuyet
sieu cao tan ta phai nghien cuu rat nhieu khia canh ma no anh huong den qua trinh
truyen song. NhiJng thong so nay chiing ta khong he quan tam khi chiing ta lam viec
/

•\

f

I

vox cac thiet bi tan so thap.
Khi nghien cuu qua trinh truyen song trong cac duang day chung ta phai de y
den mot so truong hgp dac biet ciia cac duong day truyen song, do la nhirng duong
day truyen song ma ta se ap dung rat nhieu cac dac tinh dac biet ciia chiing de thiet
ke che tao cac phan tii thu dgng sieu cao tan. Cac loai duong day do co the la mot
doan duong day mot phan tu buac song hay doan duang day mot nua buoc s6ng
trong cac truong hgp ngan mach va ha mach.
De CO th^ ti^n hanh dugc qua trinh thiet ke cac phan tu thu dgng sieu cao tan
bang cac loai duong day truyen song, chiing toi phai dac biet chii y den mot phuang
phap xk\ manh do la phuang phap ma tran va coi tat ca cac phan tii sieu cao tan la
nhirng mang hai cua, 3 cua , 4 ciia hay n ciia. Phuong phap ma tran cho phep chiing
ta thuc hien cac phep bien doi tuong duong, bien cac dang duong day truyen song
phiic tap, hay cac mach dien phiic tap thanh cac dang don gian hon va de khao sat
ban, hay la biSn cac mach dien bao gom cac phan ni phan bo thanh cac mach dien
chi bao gom cac phan tu tap trung.

III. Nghien CLPU thi§t k§ va che tao
Cac ph4n tii tap trung thuong dugc sii dung de che tao cac mach dien boat dgng a
tin s6 th§p. Nhung dS thi^t k§ cac mach dien boat dgng a tan so sieu cao thi cac
ph4n tu nay khong con phii hgp niia boi vi cac cac linh kien tap trung chi co mot s6
gia tri giai han. Vi vay thiet ke cac mach dien bang cac phan tii phan bo giiip cho ta
khic phuc dugc nhugc diem nay.

20

Bdo cdo tdng hap de tdi NCKH cdp BHQGHN
Nhung vanfeuo^^dau tien de thiet ke mot mach dien sieu cao tan hay phan tii thu
dgng sieu cao tan, chiing ta phai di tir viec nghien cuu che tao cac ph4n tii thu dgng
theo cac phuong phap truyen thong, bang cac phan tii tap trung. Sau do su dung cac
phuong phap bien doi tuong duong de chuyen doi cac phan tii tap trung thanh cac
phan III phan bo Qua trinh bien doi tuong duang tu cac mach tap trung thanh cac
f

-y

mach phan bo dugc thuc hien bang viec sii dung phuang phap ma tran.
'

>

f

t

Viec che tao cac phan tii thu dgng la viec thuc hien cac thiet ke tren mach in. Cu
the la chiing ta tao ra cac duong day truyen song theo thiet ke tren cac vat lieu sieu
cao tan. Co nhieu phuang phap de thuc hien cac duong day truyen song tren vat lieu
sieu cao tan. Ta co the tao ra chiing bang cac duang day vi dai, hay bang ong dan
song. Moi duong day vi dai dugc dac trung boi cac thong so nhu, tro khang dac
tinh, hang so dien moi va do dan dien cua vat lieu lam nen duong day truyen song.
f

\

r

•>

I

Ly thuyet sieu tan neu ra cac cong thiic de tinh cac thong so nay doi voi mot
duang day vi dai cho truoc. Dua tren thiet ke va cac thong so ve dien ciia mot
duong day vi dai, chiing toi sii dung cac cong thiic ciia ly thuyet sieu cao tan de tinh
cac tham so hinh hgc ciia cac duang day do. Sii dung cac cong cu thiet ke mach nhu
Protell 99 chiing toi thiet ke mach cac phan tii thu dgng theo cac tham so hinh hgc
ciia chiing.
r

f

f

t

\

f

I

f

\

f

f

IV. Do dac va hieu chinh
Sau khi da c6 ban mach thuc te chiing toi tien hanh do dac va kiem tra ket qua
y

f

f

f

f

nhan dugc so voi yeu cau thiet ke, va cac chi tieu dat ra trong qua trinh thiet ke. Qua
trinh nay dugc thuc hien tai phong thi nghiem cua trung tam nghien cuu Dien tuVien thong, DH Cong Nghe, DHQG Ha Ngi. Tai day, chiing toi co mot so may moc
chuyen dung nhu la may Network Analyzer, Speactrum Analyzer, vw.
f

Thong
f

thuong, cac ket qua nhan dugc tir phep do thuong co chiit sai lech so voi ket qua ly
thuyet, vi vay doi hoi phai co sir hieu chinh hinh hgc ciia cac duong day truyen s6ng.
Sau khi hieu chinh dat dugc ket qua mong muon, chiing toi tien hanh viec thilt kl va
f

che tao lai

21


Bdo cdo tdng hap di tdi NCKH cap BHQGHN
V. Nghien ciju phat trien
Sau mot thoi gian dai tham gia nghien ciiu chS tao cac phin tii sieu cao tan va da
tich luy dugc nhieu kien thiic va kinh nghiem. chiing toi huong toi muc tieu phat
trien. Tiic la nghien ciiu che tao cac pattern mai, cac phuang phap thiet ke moi, de
f

•y

t

\

r

\

nham che tao ra dugc cac san pham sieu cao tan co chat lugng ngang bang voi cac
san pham co tren thi truong the gioi, tham chi con tot ban. Va ket qiia la chiing toi
da che tao dugc mot mau bg Igc thong dai bang rgng c6 cau tnic don gian, kich
f

•*

f

f

f

f

f

r

r

thuoc nho va chat lugng rat tot. Thanh qua nay da dugc mot Hoi nghi quoc te
chuyen de ve song sieu cao tan cong nhan va cho phep dang tai proceedings ciia hoi
nghi. Trong thai gian toi, chiing toi tiep tuc theo duoi phuang huong nay.

22


Bdo cdo tdng hap di tdi NCKH cdp DHQGHN

Chu'O'ng III: Thiet k§ bo khuech dai sieu cao tin
Bg khuech dai cong suat la mot phan tu khong the thieu trong d5u cuoi v6 tuy^n. No
thuc hien nhiem vu khuech dai cong suit truac khi ra anten de tin hieu co th^ truyen
dugc di xa.
Viec thiet ke bg khuech dai nay tai cac tan so sieu cao la van de lien quan den cac ky
thuat sieu cao tan.
I. Cac bu'O'c c i n thiic hien khi thi6t ke:

1. Dua vao dac diem dieu che cua tin hieu de quyet dinh bg khuech dai boat dgng a
f

f

r

y,

f

t

che do tuyen tinh hay phi tuyen, dai tan lam viec, he so khuech dai.
f

^

2. Lira chgn transistor voi cac thong so ban dau:
- Dai tan lam viec
-

Hieu suat ciia bg khuech dai

-

He so khuech dai

3. Nghien ciiu datasheet cua transistor da lira chgn
'f

I

f

4. Dat diem lam viec cho transistor de c6 dugc hieu suat lira chgn (A, AB, B)
5. Thuc hien viec phoi hgp tro khang tai loi vao va loi ra ciia transitor de co dugc
r

f

f

t

r

cong suat ra cue dai
t

r

'

'

^

^

De CO dugc bg khuech dai cong suat Ion, he thong phai bao gom mot vai tang
khulch dai ghep n6i tiep voi nhau. Cac bg khuech dai tang dau tien thuong c6 he so
khulch dai Ion nhung cong suat loi ra khong cao lam (nghTa la khuech dai tin hieu tu
rat nho len miic cong su4t trung binh). Con cac tang sau thi co he so khuech dai nho
nhung cong suit ra Ion. Bg khuech dai sieu cao tan cong suat nho chinh la tang tien
khuech dai trong he thong khulch dai cong suat tai tram co so. Ban than cac tang
ti^n khuSch dai cung la cac IC tich hgp mot so tang khuech dai trong do.
Bg khulch dai cong suit nho ma de tai lira chgn da chgn IC MHW707-2 ciia
hang MOTOROLA IC gom 3 tang khuSch dai dugc tich hgp ben trong.
/

f

Viec thiet ke thuc hien:
23