[Photo] Lecture 1 Basic knowledge of antenna

The main parameters that characterize the performance of the antenna are the pattern, gain, input impedance, standing wave ratio, polarization mode, etc.

1.1 Input impedance of the antenna The input impedance of the antenna is the ratio of the input voltage at the antenna feed end to the input current. For the connection between the antenna and the feeder, the best case is that the input impedance of the antenna is pure resistance and is equal to the characteristic impedance of the feeder. At this time, there is no power reflection at the feeder terminal, and there is no standing wave on the feeder. The input impedance of the antenna changes smoothly with frequency. The matching work of the antenna is to eliminate the reactance component in the input impedance of the antenna and make the resistance component as close as possible to the characteristic impedance of the feeder. The pros and cons of matching are generally measured by four parameters namely reflection coefficient, traveling wave coefficient, standing wave ratio and return loss. There is a fixed numerical relationship between the four parameters, and it is purely customary to use that one. In our daily maintenance, standing wave ratio and return loss are mostly used. The input impedance of a general mobile communication antenna is 50Ω.

Standing wave ratio: It is the reciprocal of the traveling wave coefficient, and its value is between 1 and infinity. A standing wave ratio of 1 indicates a perfect match; a standing wave ratio of infinity indicates total reflection and complete mismatch. In mobile communication systems, the standing wave ratio is generally required to be less than 1.5, but in practical applications VSWR should be less than 1.2. Excessive VSWR will reduce the coverage of the base station and cause increased interference in the system, affecting the service performance of the base station.

Return loss: It is the reciprocal of the absolute value of the reflection coefficient, expressed in decibels. The value of the return loss is between 0dB and infinity. The greater the return loss, the worse the matching, and the larger the return loss, the better the matching. 0 means total reflection, and infinity means a perfect match. In mobile communication systems, return loss is generally required to be greater than 14dB.

1.2 Antenna polarization method The so-called antenna polarization refers to the direction of the electric field strength formed when the antenna radiates. When the electric field strength direction is perpendicular to the ground, this wave is called a vertically polarized wave; when the electric field strength direction is parallel to the ground, this wave is called a horizontally polarized wave. Due to the characteristics of radio waves, when the signal propagated by horizontal polarization is close to the ground, a polarization current will be generated on the surface of the earth. The polarization current will rapidly attenuate the electric field signal due to the thermal energy generated by the impedance of the earth, while the vertical polarization method is not easy Polarized current is generated, thereby avoiding a large attenuation of energy and ensuring the effective propagation of the signal.

Therefore, in the mobile communication system, the vertically polarized propagation method is generally adopted. In addition, with the development of new technologies, a dual-polarized antenna has recently appeared. In terms of its design ideas, it is generally divided into two ways: vertical and horizontal polarization and ± 45 ° polarization, and the latter is generally superior to the former in performance, so most of the current uses are ± 45 ° polarization. The dual-polarized antenna combines + 45 ° and -45 ° antennas with mutually orthogonal polarization directions, and works simultaneously in the transceiver duplex mode, which greatly saves the number of antennas in each cell; Orthogonal polarization effectively guarantees the good effect of diversity reception. (The polarization diversity gain is about 5dB, which is about 2dB higher than the single-polarized antenna.)

1.3 Antenna gain Antenna gain is used to measure the ability of the antenna to send and receive signals in a specific direction. It is one of the most important parameters for selecting a base station antenna.

In general, the increase in gain mainly depends on reducing the width of the lobe facing the radiation vertically, while maintaining the omnidirectional radiation performance on the horizontal plane. Antenna gain is extremely important to the operational quality of mobile communication systems because it determines the signal level at the edge of the cell. Increasing the gain can increase the coverage of the network in a certain direction, or increase the gain margin within a certain range. Any cellular system is a two-way process. Increasing the gain of the antenna can simultaneously reduce the gain budget margin of the two-way system. In addition, the parameters characterizing the antenna gain are dBd and dBi. DBi is the gain relative to the point source antenna, and the radiation in all directions is uniform; dBd is relative to the gain of the symmetric array antenna dBi = dBd + 2.15. Under the same conditions, the higher the gain, the farther the radio wave travels. Generally, the antenna gain of a GSM directional base station is 18dBi, and omnidirectional is 11dBi.

1.4 The lobe width of the antenna The lobe width is a very important parameter commonly used in directional antennas. It refers to the width of the angle formed by the antenna radiation pattern below the peak 3dB (the antenna radiation pattern is a measure of the signal received and sent in all directions of the antenna An indicator of capability, usually expressed graphically as the relationship between power intensity and included angle).

The vertical lobe width of an antenna is generally related to the coverage radius in the corresponding direction of the antenna. Therefore, by adjusting the verticality (elevation angle) of the antenna within a certain range, the purpose of improving the coverage quality of the cell can be achieved, which is also a method we often use in network optimization. It mainly involves two aspects: horizontal lobe width and vertical plane lobe width. H-Plane Half Power beamwidth: (45 °, 60 °, 90 °, etc.) defines the beam width of the antenna horizontal plane. The larger the angle, the better the coverage at the sector junction, but when the antenna tilt angle is increased, the beam distortion is more likely to occur, resulting in cross-region coverage. The smaller the angle, the worse the coverage at the sector junction. Increasing the antenna inclination can improve the coverage of the sector junction in the degree of movement, and relatively speaking, it is not easy to produce cross-coverage to other cells. In the city center, the base station has a small station distance and a large antenna tilt angle. An antenna with a small half-power angle in the horizontal plane should be used. An antenna with a large half-power angle in the horizontal plane is selected in the suburbs; ): (48 °, 33 °, 15 °, 8 °) defines the beam width of the vertical plane of the antenna. The smaller the half-power angle of the vertical plane, the faster the signal attenuation when deviating from the main beam direction, and the easier it is to accurately control the coverage area by adjusting the antenna tilt angle.

1.5 Front-Back RaTIo
This shows how well the antenna suppresses the back lobes. An antenna with a low front-to-back ratio is selected, and the rear lobes of the antenna may produce cross-over coverage, resulting in chaotic switching relationships and dropped calls. Generally between 25-30dB, antennas with a front-to-back ratio of 30 should be preferred.

Follow WeChat

Interesting and informative information and technical dry goods

Download Audiophile APP

Create your own personal electronic circle

Follow the audiophile class

Lock the latest course activities and technical live broadcast

related suggestion

QSFP28 Optical Module Topic: Introduce the basic knowledge and types of QSFP28 optical modules

Published on 2018-03-15 14:20 • 106 times read

Labview basics

Published on 2018-03-08 17:56 • 581 times read

ARM basics

Published on 2018-01-25 02:23 • 840 views

Popularization of basic audio knowledge

It is precisely because of fever and audio equipment that has promoted the development of audio equipment and the improvement of cultural taste. Therefore, fever activities are welcomed by the public. As for the hair ...

Published on 16:36 2012-11-06 • 28456 times read

Briefly introduce the relevant basic knowledge of LTE test technology

Long-term evolution (LTE) wireless networks present several challenges to test equipment vendors. The LTE air interface defined by 3GPP adopts positive ...

Posted at 2012-07-17 10:35 • 586 views

Data communication basic knowledge summary

1. Composition principle, exchange method and applicable scope of data communication 1. Composition principle of data communication DTE is a data terminal. Data terminals are grouped ...

Posted at 2012-07-03 15:51 • 1235 views

Some basic knowledge of data collection

This article introduces the various components of the data acquisition system in detail and explains the most important guidelines for each component. This article also defines the number used for PC-based ...

Posted at 2012-06-14 10:34 • 2312 views

Principles and basic knowledge of touch screen

At present, there are mainly several types of touch screens, which are: resistive (double layer), surface capacitive and inductive capacitive, surface acoustic wave, infrared ...

Published in 16:47 2012-06-13 • 1190 times read

Design guide for floating measurement and isolated input oscilloscope

This application note will introduce power measurement terms, explain the different options available for floating measurements, and highlight the advantages and disadvantages of each option. ...

Posted at 2012-03-27 17:13 • 2318 views

Detailed explanation of sensor basic knowledge (1)

The national standard GB7665-87 defines the sensor as: "A device that can feel the specified measured and converted into a usable signal according to a certain rule ...

Posted at 2012-03-20 10:30 • 22843 views

100 Questions about Basic Knowledge of Oscilloscope (Part 1)

The oscilloscope has already become one of the most effective tools for detecting electronic circuits. By observing the voltage and current waveforms of key nodes of the line, you can intuitively check the line ...

Posted at 2012-03-16 11:52 • 15305 views

Basic knowledge of LCD

Basic knowledge of LCD display ☆ Resolution ...

Posted at 2011-04-03 23:38 • 8320 views

Basic knowledge of lightning protection components

This article introduces TVS, glass discharge tube, varistor, ceramic gas discharge tube, semiconductor discharge tube, self-recovery insurance ...

Published on 08:36 2011-01-15 • 7250 views

PoC basics

PoC basics PoC-Push to Talk over Cellular & nb ...

Published on 2010-01-11 10:39 • 784 views

Hard drive basics

Hard disk basics When you talk about hard disks, you must be familiar with them. My Windows 98 is installed on the hard disk, and my hard disk ...

Posted at 2009-12-25 15:38 • 466 times read

Basic knowledge of microwave circuit and design

Posted at 2009-08-24 01:45 • 25042 views

Basic knowledge of digital camera repair

Digital camera repair basic knowledge Digital camera is also called digital camera, referred to as DCS (Digital Still Camera ...

Published on 2008-10-17 17:27 • 310 views

Basic knowledge of speakers

The structure of the speaker 1. There are many types of speakers

Published on 2006-04-17 23:44 • 571 views

Basic knowledge of display maintenance

"Display Maintenance Basics" & nbs ...

Posted at 2006-04-17 22:51 • 247 views

SMT basics

1 Standard parts

Published on 2006-04-17 20:47 • 1515 views

Basic knowledge of single chip microcomputer

The composition of single chip ...

Published on 2006-04-17 19:57 • 819 times read

Basic knowledge of components

Section 1 Identification of Common Components 1. Resistance "R" is used in the circuit ...

Posted at 2006-04-16 23:47 • 281 views

Basic knowledge of capacitors

Lecture 1: The characteristics of capacitors

Posted at 2006-04-16 23:47 • 1618 views

Basic knowledge of circuit diagrams

First, the significance of electronic circuit diagrams Circuit diagrams are for research and engineering ...

Posted at 2006-04-16 23:33 • 8307 views

Basic knowledge of electronic technology

Section 1 Identification of Common Components

Posted at 2006-04-16 23:33 • 30676 views

Basic knowledge of remote control circuit

The electric remote control toy also adds a remote control circuit to the electric toy. Common remote control circuits are ...

Posted at 2006-04-16 22:40 • 365 times read

Basic knowledge of hardware engineers

Purpose: Based on actual experience and actual project to understand and master the qualification of becoming a qualified hardware engineer in detail ...

Posted at 2006-04-16 22:19 • 1543 views

Basic knowledge of printed board

...

Published on 2006-04-16 21:55 • 151 views

FPC basic knowledge

...

Posted at 2006-04-16 21:13 • 173 views

Basic knowledge of PCB design

Printed circuit board (Printed circuit board, P ...

Posted at 2006-04-16 20:22 • 237 views

Basic knowledge of radio

Basic knowledge of radio 1. Interpretation of radio communication terms [audio], also known as audio, is what the human ear can ...

Posted at 2006-04-16 19:03 • 4207 views

[Photo] What is the basic knowledge of PN junction and semiconductor

In our daily life, we often see or use various objects, it ...

Posted at 2006-04-15 23:00 • 1040 reading

'+ data.username +'

Quit '; * / var login_content =' write an article

'+ data.username +'

Set exit '; $ (' # login_area '). Html (login_content); var win_width = $ (window) .width (); if (win_width> 1000) {$ ("# mine"). MouseDelay (200) .hover (function () {$ ("# mymenu"). show ();}, function () {$ ("# mymenu"). hide ();});}} else {var content = 'Login Registration'; $ ('# login_area'). html (content); $ (". special-login"). click (function (e) {$ .tActivityLogin (); return false;});}});} $ (function () {// comment ------------------------------- var comment = $ ("# comment"); var comment_input = $ ("# comContent"); // Submit comment click event interaction $ ("# comSubmit2"). on ('click', function () {var content = comment_input.text (); // Empty input box comment_input. html (""). focus (); // Submit data to server $ .ajax ({url: '/plus/arcComment.php', data: {aid: $ ("# webID"). val (), dopost : 'apiPubComment', content: content}, type: 'post', dataType: 'json', success: function (data) {// Data format returned: if (data.status == "successed") {// Build temporary comment DOM var dom = ''; dom + = '

'; dom + =' '; dom + ='

'; dom + ='

'+ data.data.username +' '; dom + ='

'; dom + =' '+ content +' '; dom + =' '; dom + =' just now '; dom + =' '; dom + =' '; // insert a temporary comment to the list $ ("# comment ") .append (dom);} if (data.status ==" failed ") {// alert (data.msg); layer.msg (data.msg);}}}); return false;}); (function () {/ * * Insert single sign-on JS * / var setHost = 'https://passport.elecfans.com'; // Set domain name var script = document.createElement ('script'); script.type = 'text / javascript'; script.src = setHost + '/public/pc/js/t.passport.js'; script.setAttribute ("id", "sso_script"); script.setAttribute ("data-ssoSite", setHost); script.setAttribute ("data-ssoReferer", encodeURIComponent (location.href)); script.setAttribute ("data-ssoSiteid", "11"); var body = document.getElementsByTagName ("body"). item ( 0); body.appendChild (script);}) () / * * It is recommended to modify the style of the article without a picture * * / $ (". Article .thumb"). Each (function () {if ($ (this). find ('img'). attr ('src') == "") {$ (this) .find ('img'). remove (); $ (this) .parent (). css ('padding-left ',' 0px ');}}); / * Baidu share * / window._bd_share_config = {common: {bdText: '', // Custom share content bdDesc: '', // Custom share summary bdUrl: window.location.href, // Custom share URL address bdPic: ''} , share: [{"bdSize": 60, "bdCustomStyle": true}]} with (document) 0 [(getElementsByTagName ('head') [0] || body) .appendChild (createElement ('script')). src = 'http://bdimg.share.baidu.com/static/api/js/share.js?cdnversion=' + ~ (-new Date () / 36e5)]; var add_url = '/ d / article / write / '; // var check_allow = "{: U (' Api / iscantalk ')}"; var check_allow = "/ d / api / iscantalk"; var click_items_length = $ ('. art_click_count '). length; if ( click_items_length> 0) {var id_str = ''; $ ('. art_click_count'). each (function () {id_str + = $ (this) .attr ('data-id') + ',';}) // var url = "{: U ('Api / getclickbyids')}"; var url = "/ d / api / getclickbyids"; var id_data = 'id_str =' + id_str; $ .ajax ({url: url, data: id_data, type: 'post', dataType: 'json', success: function (re) {if (re.list.length> = 1) {var list = re.list; for (var i in list) {var t emp_id = list [i] ['id']; var temp_span = $ (". art_click_count [data-id =" + temp_id + "]") temp_span.html (list [i] ['click']);}} }})} $ ("# comContent"). click (function () {if (now_uid == '') {$ .tActivityLogin (); return false;}}) $ (function () {var follow_wrap = $ ( ".author-collect"); var now_uid = "{$ _super ['uid']}"; var face_src = "{$ _super ['uface']}"; var getFollowNum = $ (". followNum strong"). html (); // Follow $ (window) .on ('click', '.author-collect', function () {if (now_uid == '') {$ .tActivityLogin (); return false;} if ( $ (this) .attr ('id') == 'follow') {$ .post ('/ d / user / follow', {tuid: article_user_id}, function (data) {// Data format returned: if (data.status == "successed") {$ (". followNum strong"). html (++ getFollowNum); follow_wrap.html ('followed'). attr ('id', 'cancelFollow'). css ( 'background', '# 999'); var follow_user = ' '; $ (' # follow_list '). append (follow_user);} if (data.status == "failed") {alert (data.msg);}});} else {// Unfollow if ($ ( this) .attr ('id') == 'cancelFollow') {$ .post ('/ d / user / cancelFollow', {tuid: article_user_id}, function (data) {// Data format returned: if (data .status == "successed") {follow_wrap.html ('Follow'). attr ('id', 'follow'). css ('background', '# f90'); $ (". followNum strong"). html (-getFollowNum); $ ('# follow_list .face'). each (function () {var target_uid = $ (this) .attr ('data-uid'); if (target_uid == now_uid) {$ ( this) .remove ();}})} if (data.status == "failed") {alert (data.msg);}}); return false;}}});});}); / * var myface = "{$ _super ['uid'] | avatar}"; var myname = "{$ _super ['username']}"; var article_id = {$ article ['id']}; var article_user_id = {$ article ['mid']}; // Article author ID $ (function () {<notempty name = "clearnum"> // Reduce the number of reminders var count = parseInt ($ ("# noticeCount"). html ()); count = count-{$ clearnum}; $ ("# noticeCount"). html (count); if ( count

A cable is a component that connects one or more wires that can be insulated or used to transfer electrical energy or signals. Used as a primary overhead conductor for primary and secondary distribution. Designed for use with high strength aluminum alloys to achieve high strength to weight ratios; provides good droop characteristics. AAAC, ACSR is part of a series of overhead conductors, transmission conductors and distribution conductors. These cables are officially referred to as all-aluminum conductors (AAAC) and aluminum conductor bars (ACSR). These overhead aluminum conductors are used as power transmission and distribution lines. Depending on the application, all aluminum conductors are made of one or more strands of aluminum wire.
The following are the picture and parameters of our product, for more details about the cable and fitting, please contact us. 

MAIN DIMENSIONS AND STANDARD PARTICULARS
Code Number	Stranding&wire diameter	Approx Overall diameter	Norminal Area	Approx weight	Breaking Load	DC Resistance at 20
	mm	mm	mm2	kg/km	KN	Ohm/km
16	7/1.83	5.49	18.4	50.4	5.43	1.7896
25	7/2.29	6.86	28.8	78.7	8.49	1.1453
40	7/2.89	8.68	46	125.9	13.58	0.7158
63	7/3.63	10.9	72.5	198.3	21.39	0.4545
100	19/2.78	13.9	115	316.3	33.95	0.2877
125	19/3.10	15.5	144	395.4	42.44	0.2302
160	19/3.51	17.6	184	506.1	54.32	0.1798
200	19/3.93	19.6	230	632.7	67.91	0.1439
250	19/4.39	22	288	790.8	84.88	0.1151
315	37/3.53	24.7	363	998.9	106.95	0.0916
400	37/3.98	27.9	460	1268.4	135.81	0.0712
450	37/4.22	29.6	518	1426.9	152.79	0.0641
500	37/4.45	31.2	575	1585.5	169.76	0.0577
560	61/3.67	33	645	1778.4	190.14	0.0516
630	61/3.89	35	725	2000.7	213.9	0.0458
710	61/4.13	37.2	817	2254.8	241.07	0.0407
800	61/4.38	39.5	921	2540.6	271.62	0.0361
900	91/3.81	41.8	1036	2861.1	305.58	0.0321
1000	91/4.01	44.1	1151	3179	339.53	0.0289
1120	91/4.25	46.7	1289	3560.5	380.27	0.0258
1250	91/4.49	49.4	1439	3973.7	424.41	0.0231

MAIN DIMENSIONS AND STANDARD PARTICULARS
Code Number	Stranding&wire diameter		Approx Overall diameter	sectional Area			Approx weight	Breaking Load	DC Resistance at 20
	AL(mm)	Steel(mm)	mm	Al(mm2)	Steel(mm2)	Total(mm2)	kg/km	KN	Ohm/km
16	6/1.84	1/1.84	5.53	16	2.67	18.7	64.6	6.08	1.7934
25	6/2.3	1/2.30	6.91	25	4.17	29.2	100.9	9.13	1.1478
100	6/4.61	1/4.61	13.8	100	16.7	117	403.8	34.33	0.2869
125	18/2.97	1/2.97	14.9	125	6.94	132	397.9	29.17	0.2304
160	18/3.36	1/3.36	16.8	160	8.89	169	509.3	36.18	0.18
250	22/3.80	7/2.11	21.6	250	24.6	275	880.6	68.72	0.1154
400	54/3.07	7/3.07	27.6	400	51.9	452	1510.3	123.04	0.0723
450	54/3.26	7/3.26	29.3	450	58.3	508	1699.1	138.42	0.0643
500	54/3.43	7/3.43	30.9	500	64.8	565	1887.9	153.8	0.0578
560	54/3.63	19/2.18	32.7	560	70.9	631	2103.4	172.59	0.0516
630	54/3.85	19/2.31	34.7	630	79.8	710	2366.3	191.77	0.0459
710	54/4.09	19/2.45	36.8	710	89.9	800	2666.8	216.12	0.0407
800	72/3.76	7/2.51	37.6	800	34.6	835	2480.2	167.41	0.0361
900	72/3.99	7/2.66	39.9	900	39.9	939	2790.2	188.33	0.0321

We warmly welcome friends both domestic and abroad to visit our company,if you have any questions, please contact with us directly.

Cable And Fittings

Aluminum Electrical Wire,Aluminum Power Cable,Aluminum Wire Connectors,Aluminum Electrical Cable

FUZHOU SINGREE IMP.& EXP.CO.,LTD. , https://www.cninsulators.com