200522441 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種具有UHF頻帶之電視接收環路天線。 【先前技術】 在美國專利第6,429,828號中描述了這樣一種室内UHF天 線’其係一直徑約20釐米之環路。 【發明内容】 本發明之一目的係提供一種接收Uhf訊號之天線，其具 有相對較小之尺寸。本發明之另一目的係提高訊雜比。 根據本發明，具有UHF頻帶之電視接收環路天線係可調 諸的。因此，就其波長而言，該天線之尺寸很小。其直徑 僅約5羞米。一 470百萬赫之廣播訊號對應之波長為64釐 米。一 870百萬赫之廣播訊號對應之波長為34釐米。提供 一種尺寸為5釐米之用於超高頻電視接收（簡稱為uhf TV 接收）之手持天線。訊雜比與天線之方向性成正比。對於 一便攜式電視接收器，希望擁有一全向系統。忽略天線之 方向性，取最小訊雜比，簡稱SNR。 【實施方式】 參考以下說明及隨附圖示可以很好地理解本發明及其另 外之目的與優點。 圖1與圖2顯示一環路天線i，其包含一環路2、一調諧電 谷器3(間記為c〇)及一輻射電阻4(簡記為Rr)。環路2擁有一 直徑5。放大器6對環路天線1之輸出7之訊號進行放大。輻 射電阻4、線圈8(簡記為L〇)、損耗電阻9(簡記為Rloss skin)及 97098.doc -6- 200522441 電壓源10代替環路2。電磁場11 (簡記為Hi或Ε/ίί場）感應出 電壓ΐ2(簡記為Vi)。輸入端之訊雜比（簡記為SNRin)考慮到 輻射電阻4之雜訊及來自天線之訊號。輪出13處之訊雜比 (簡記為 SNR〇ut)定義為·· 。NF_咖 為調諧電容器3與放大器6之雜訊因數。插入一與環路之並 耳汁之电今态3，用以消除將雜訊與功率匹配於放大器6之電 容。這一系統與環路2之共振係用於選擇頻道。對於一固 定環路2,如果串聯電阻4、9不隨頻率變化，則頻寬保持 恒定。在此情況下，可調諧環路天線i用作一天線及一跟 縱遽波器。由於集膚效應之緣故，存在一損耗電阻9 ,直 與天線之輸入阻抗4串聯。這一損耗電阻9使天線產生雜 汛。於是，天線1之雜訊因數為： NF = 10. l〇g^~L+ R丨。ss skin ) 應使與環路2之輕射電阻4串聯或與㈣電容^ 耗電阻9最小化’因為它可以增大整體雜訊因數。 二：電容器3之緣故’可以對擁有線圈8、輕射電阻植 €阻之環路天線1進行調譜。因此，此共振電路之1、 質因數為： 电每之口口 q=^L·-^ =效輸人電壓為··www，其中 場路面積，μ自由空間磁導接又之Η200522441 IX. Description of the invention: [Technical field to which the invention belongs] The present invention relates to a television receiving loop antenna having a UHF frequency band. [Prior Art] Such an indoor UHF antenna is described in U.S. Patent No. 6,429,828 as a loop having a diameter of about 20 cm. SUMMARY OF THE INVENTION An object of the present invention is to provide an antenna for receiving Uhf signals, which has a relatively small size. Another object of the present invention is to improve the signal-to-noise ratio. According to the present invention, a television receiving loop antenna having a UHF band is adjustable. Therefore, the size of the antenna is small in terms of its wavelength. Its diameter is only about 5 cm. A 470 MHz broadcast signal corresponds to a wavelength of 64 cm. A 870 MHz broadcast signal corresponds to a wavelength of 34 cm. Provide a handheld antenna with a size of 5 cm for UHF TV reception (referred to as uhf TV reception). The noise to noise ratio is directly proportional to the directivity of the antenna. For a portable TV receiver, it is desirable to have an omnidirectional system. Ignore the directivity of the antenna, and take the smallest signal-to-noise ratio, referred to as SNR. [Embodiment] The present invention and other objects and advantages thereof can be well understood with reference to the following description and accompanying drawings. Fig. 1 and Fig. 2 show a loop antenna i, which includes a loop 2, a tuning valleyr 3 (indicated as c0) and a radiation resistance 4 (abbreviated as Rr). Loop 2 has a diameter of 5. The amplifier 6 amplifies the signal of the output 7 of the loop antenna 1. Radiation resistance 4, coil 8 (abbreviated as L0), loss resistance 9 (abbreviated as Rloss skin), and 97098.doc -6- 200522441 voltage source 10 instead of loop 2. Electromagnetic field 11 (abbreviated as Hi or Ε / ίί field) induces voltage ΐ2 (abbreviated as Vi). The signal-to-noise ratio at the input (referred to as SNRin) takes into account the noise from the radiation resistance 4 and the signal from the antenna. The signal-to-noise ratio (abbreviated as SNR〇ut) at 13 rounds is defined as ... NF_Ca is the noise factor of tuning capacitor 3 and amplifier 6. An electric current state 3 inserted in parallel with the loop is used to eliminate the capacitor matching the noise and power to the amplifier 6. This system's resonance with Loop 2 is used for channel selection. For a fixed loop 2, if the series resistances 4 and 9 do not change with frequency, the bandwidth remains constant. In this case, the tunable loop antenna i is used as an antenna and a longitudinal wave filter. Due to the skin effect, there is a loss resistance 9 directly connected in series with the input impedance 4 of the antenna. This loss resistance 9 causes miscellaneous flooding of the antenna. Therefore, the noise factor of antenna 1 is: NF = 10. l0g ^ ~ L + R 丨. ss skin) should be in series with the light-emitting resistor 4 of the loop 2 or minimized with the capacitor ^ dissipation resistor 9 'because it can increase the overall noise factor. 2: Capacitor 3's spectrum adjustment can be performed on the loop antenna 1 which has a coil 8 and a light transmitting resistor. Therefore, the quality factor of this resonance circuit is: 1. Power per port q = ^ L ·-^ = Effective input voltage is www., Where the field path area, μ free space magnetic permeance connection is another
對於共振，7與地線間之有效輸㈣壓為：VQ%V 在圖3中，曲線21、22、23 S§ -山 1 23顯不出環路直徑5為3、4 97098.doc 200522441 ί:時雜訊因數隨頻率之變化。在區間斗與該結構之 可生電容相比，電容器3之值變得非常小，c變為小以奸。 θ如果：大直徑5，雜訊因數(簡記為叫將提高。不幸的 :’其运將增大環路2之電感值，這樣即不可能調譜至最 而頻率’其原因在於其需要難以實現之小電容器3,其取 =會党環路寄生電容之限制。幸運地是，r—狀與 頻率相關的方式會促使财對於更高頻率而有所改良。這些 效應在圖3中說明。 圖4顯示若干架構，其可以提高頻率而不會增大雜訊因 數。 圖4A顯不-天線3卜其包含兩個環路、η與一並聯插 入t調”容㈣。環路32及33包含線。電容器 34(間記為C2)對天線31進行調言皆。如果該等兩個環路η、 33與圖i中天線i之環路相同，則[ο%%。要計算輻射電 阻’可以在天線Μ上插入一電流源。當圖丨、圖4a中之天 線1與天線31中之電流相同時，所輻射之場與^實例 中之E/Η場相同。這就意味著^與圖乜中之兩個天線旧 31具有相@之輻射電a。由於這種組態之等效電感為 Li/2，所以Rloss skin被降低。為獲得與圖i實例相同之頻 率’ C2=2:C〇。等效輸入電壓保持不變。互柄現象未予以 考慮。當電容器34較大時，極易提高頻率，但其面積加 倍。 W/w = Rr+- R loss skin 2For resonance, the effective input pressure between 7 and ground is: VQ% V In Figure 3, the curves 21, 22, and 23 S§-Shan 1 23 do not show the loop diameter 5 is 3, 4 97098.doc 200522441 ί: Time noise factor changes with frequency. In the interval bucket, the value of the capacitor 3 becomes very small compared to the generateable capacitance of the structure, and c becomes small. θ if: large diameter 5, the noise factor (referred to as called will increase. Unfortunately: 'its operation will increase the inductance value of loop 2, so it is impossible to tune the spectrum to the highest frequency' because its need is difficult The small capacitor 3 implemented is limited by the parasitic capacitance of the party loop. Fortunately, the frequency-dependent manner of r-shape will promote the improvement of higher frequencies. These effects are illustrated in Figure 3. Figure 4 shows several architectures that can increase the frequency without increasing the noise factor. Figure 4A shows that the antenna 3 includes two loops, η and a parallel insertion t-tuning capacitor. Loops 32 and 33 Contains wire. Capacitor 34 (indicated as C2) is used for both antenna 31. If the two loops η, 33 are the same as the loop of antenna i in Figure i, then [ο %%. To calculate the radiation resistance 'You can insert a current source on the antenna M. When the current in antenna 1 and antenna 31 in Figure 丨 and Figure 4a is the same, the radiated field is the same as the E / Η field in the example. This means ^ The two antennas shown in Figure 旧 have 31 radiated electricity a. Because the equivalent inductance of this configuration is Li / 2, so The Rloss skin is lowered. In order to obtain the same frequency as the example in Figure i, 'C2 = 2: C0. The equivalent input voltage remains unchanged. The cross-talk phenomenon is not considered. When the capacitor 34 is large, it is easy to increase the frequency. But its area is doubled. W / w = Rr +-R loss skin 2
QQ
Rr + R loss skin /2^|4C0 97098.doc 200522441 當Li#L2時，對於圖4A之組態，公式變為：Rr + R loss skin / 2 ^ | 4C0 97098.doc 200522441 When Li # L2, for the configuration of Figure 4A, the formula becomes:
:〔S1 Zr2 — | S2 Ιλ I R ^ S0 Lx + L2 S0 Lx + L2) _ L2vn ( Lxyn 1 Lx L2 Lx+ L2 31 與 32 與苐 之表 環略 式中，So、Si、S2為參考環路2及兩個並聯i袠略 面積。Rr總是介於1^與111：2之間。若一環路3l 32相比非常大，則該電路等效於最小之環路32 圖4B說明一天線41，其包含一電容器42與@ 、长略4 3 電容器42與環路43-45為並聯插入。環路43、45 LI、L2及L3。天線41之調諧方式包括：以 包含 電容 45 〇 線圈 進行精密調諧，增加若干並聯環路43-45進〜11 42 4 丁離黄丈匕匕 諳。在完成此調諧時，不得增加有關輻射電^ @階調 件。可以採用機械方式以螺絲、機電式繼電II & α來實現，丄 可以採用一微機電系統（簡記為MEMs)以電孓+ 也 ▲ 式實現。 請參見網際網路之内容： EMR與 MEMs : http://www.simplernetworks.com/eng/index.htnxi http://www.memsrus.com/CIMSprod.html 用於高頻應用之微型機械繼電器：Y. Komura，μ. sakata T.Seki，K. Kobayashi, Κ· Sano，S. Horiike, K. Ozawa Omron公司 http://www.omron.co.jp/r_d/doc/mmr_for_hf.pdf 水銀微開關-R. Timothy Edwards C. - J. Kim http://klabs,org/richcontent/MAPLDC〇n〇l/Prp^pntation — 97098.doc 200522441 B/B2A Edwards S· pdf 南階 RF 開關技術-C · Wheeler - Micro Lab Inc. http://www.microlab. net/ 圖4C與4D顯示一環路天線51，其具有一與lc並聯電路 53並聯插入之環路52。LC並聯電路53包含一可調諧電容器 54(簡記為CO，及一線圈55(簡記為[Ο。L4之目的在於降 低C3之數值。可將其看作一降低f倍之負電容。天線5 ^之 參數與圖1實例中之參數相同。 C3f Q =_ί_ Ε 為獲得與其他實例相同之頻率，在L4=Li=Lg情況下，q為 使C3’=C〇之數值之兩倍。其相對於圖4A之優點在於其面積 縮小。缺點在於Q值為圖4A實例中之兩倍。除考慮電容器 53或54申之某些電阻損耗之外，這些項被b之負電容“放 大，使NF更差。圖4 A組態中之情況並非如此。因此，為 獲得與圖1與圖4A實例中相同之頻率，NF增大許多。 圖4E說明一天線組態6〇，其有一天線61及一放大器以。 天線61包含一環路63與三個調諧電容器64、“和66(簡記 為Ca、Cb與Cc)。環路63包含一線圈[丨。環路63與電容器幻 串耳外由電夺益64、65及ί辰路63構成之並聯電路68愈電容 器66串聯，其連接於放A|f62。包括之分接頭電路 67使天線61連接於放大器62。兩個調譜電容器64、65串聯 插入’以提高頻率。電容器64、65(簡記為CjCb)之串聯 電阻很小，因為如果其串聯電阻較大，則電容器64、65之 97098.doc -10- 200522441 此架構64、65將不能免受雜訊干擾。 圖4F顯示一天線71與一放大器72。天線71包含一環路73 與六個調諧電容器74-79。環路73包含一線圈（簡記為1^)。 四個可調電容器74-77(簡記為兩個Ca和兩個Cb)串聯插入。 環路73與電容器74和77串聯。包括電容器74和75之第一分 接頭電路8〇經由調諧電容器78使天線71連接於放大器72， 包括電容器76和77之第二分接頭電路81經由調諳電容器79 使天線71連接於放大器72。這是一種以差分方式獲得訊號 之方法。 圖4G說明一天線系統91，其具有一第一天線組態6〇及一 第二天線組態92。第二天線組態92包含一天線93與一放大 器94。天線93包含兩個並聯環路95和96及一包含調諧電容 98和99之分接頭電路97，其經由一調諧電容器1〇〇使該等 兩個環路95和96連接於放大器94。藉由切換組態60和92之 輸出103和104處之訊號獲得全部調諧範圍。兩個天線組態 60和92由開關1 〇 1隔離，來將其訊號提供至一電視接收器 102。與圖4B所示之解決方案相比，此開關不必為理想開 關。其將較少改變共振頻率、q值與NF。但這一解決方案 思味著至少兩倍之類似分接頭電路及更多環路。 圖5顯示UHF手持天線111及一放大器丨12。該天線包含 兩個環路11 3、114、一開關115及七個電容器116_ 121。每 一環路包含一線圈（簡記為Ll)。藉由開關U5向第一環路 113增加一第二環路114。電容器117和118為可變電容二極 體（Μ §己為Cvar、變容二極體）。包含環路I〗]、電容器up 97098.doc -11 - 200522441 及變容二極體118之串聯電路123與變容二極體117及電容 器116並聯。包含四個電容116-119之分接頭電路124經由 調諧電容器122將天線111連接放大器丨丨2。 環路之直徑為5釐米。Ll = 89 nH。頻率為575百萬赫時 Rr=M Ω。頻率為 575百萬赫時r1〇ss skin =〇.18 β。: [S1 Zr2 — | S2 Ιλ IR ^ S0 Lx + L2 S0 Lx + L2) _ L2vn (Lxyn 1 Lx L2 Lx + L2 31 and 32 In the abbreviated form of the ring, So, Si, and S2 are the reference loops 2 and The approximate area of two parallel i. Rr is always between 1 ^ and 111: 2. If a loop 3l 32 is very large, this circuit is equivalent to the smallest loop 32. Figure 4B illustrates an antenna 41, It includes a capacitor 42 and @, a long 4 3 capacitor 42 and loops 43-45 are inserted in parallel. The loops 43, 45 LI, L2 and L3. The tuning method of the antenna 41 includes: precision with a 45 o coil Tuning, adding a number of parallel loops 43-45 into 11 42 4 Ding Li Huang Zhang dagger. When completing this tuning, you must not increase the relevant radiant power ^ @ 级 调 件. You can use mechanical, screw and electromechanical relays. Electricity II & α can be implemented, and 丄 can be implemented by a MEMS + (▲) using a micro-electromechanical system (referred to as MEMs). Please refer to the contents of the Internet: EMR and MEMs: http://www.simplernetworks.com /eng/index.htnxi http://www.memsrus.com/CIMSprod.html Micro-mechanical relays for high-frequency applications: Y. Komura, μ. sakata T. Seki, K. Kobayashi, K. Sano, S. Horiike, K. Ozawa Omron Corporation http://www.omron.co.jp/r_d/doc/mmr_for_hf.pdf Mercury Micro Switch-R. Timothy Edwards C .-J. Kim http: // klabs, org / richcontent / MAPLDC〇n〇l / Prp ^ pntation — 97098.doc 200522441 B / B2A Edwards S · pdf South-Order RF Switching Technology-C · Wheeler-Micro Lab Inc. http://www.microlab.net/ Figures 4C and 4D show a loop antenna 51 having a loop 52 inserted in parallel with the lc parallel circuit 53. The LC parallel circuit 53 includes a tunable capacitor 54 (abbreviated as CO, And a coil 55 (abbreviated as [0. The purpose of L4 is to reduce the value of C3. It can be regarded as a negative capacitance that is reduced by f times. The parameters of the antenna 5 ^ are the same as those in the example of Figure 1. C3f Q = _ί_ Ε In order to obtain the same frequency as the other examples, in the case of L4 = Li = Lg, q is twice the value of C3 ′ = C0. Its advantage over Fig. 4A is that its area is reduced. The disadvantage is that the Q value is twice that in the example of Figure 4A. In addition to considering some of the resistive losses claimed by capacitors 53 or 54, these terms are "amplified by the negative capacitance of b, making NF worse. This is not the case in the configuration of Figure 4 A. Therefore, in order to obtain In the example of 4A, the NF increases a lot. Fig. 4E illustrates an antenna configuration 60, which has an antenna 61 and an amplifier. The antenna 61 includes a loop 63 and three tuning capacitors 64, ", and 66 (abbreviated as Ca, Cb and Cc). The loop 63 contains a coil [丨. The loop 63 is connected in series with a parallel circuit 68 and a capacitor 66 outside the ears of the capacitor phantom string consisting of the electric gain 64, 65 and the electric circuit 63, which is connected to the amplifier A | f62. The included tap circuit 67 connects the antenna 61 to the amplifier 62. Two spectrum tuning capacitors 64, 65 are inserted in series' to increase the frequency. The series resistance of capacitors 64, 65 (abbreviated as CjCb) is very small, because if the series resistance is large, the capacitors 64, 65 97098.doc -10- 200522441 This architecture 64, 65 will not be immune to noise interference. FIG. 4F shows an antenna 71 and an amplifier 72. The antenna 71 includes a loop 73 and six tuning capacitors 74-79. The loop 73 includes a coil (abbreviated as 1 ^). Four adjustable capacitors 74-77 (abbreviated as two Ca and two Cb) are inserted in series. The loop 73 is connected in series with the capacitors 74 and 77. A first tap circuit 80 including capacitors 74 and 75 connects antenna 71 to amplifier 72 via tuning capacitor 78, and a second tap circuit 81 including capacitors 76 and 77 connects antenna 71 to amplifier 72 via tuning capacitor 79. This is a way to get the signal differentially. FIG. 4G illustrates an antenna system 91 having a first antenna configuration 60 and a second antenna configuration 92. The second antenna configuration 92 includes an antenna 93 and an amplifier 94. The antenna 93 includes two parallel loops 95 and 96 and a tap circuit 97 including tuning capacitors 98 and 99, which connects the two loops 95 and 96 to an amplifier 94 via a tuning capacitor 100. The full tuning range is obtained by switching the signals at outputs 103 and 104 of configurations 60 and 92. The two antenna configurations 60 and 92 are isolated by a switch 101 to provide their signals to a television receiver 102. Compared to the solution shown in Figure 4B, this switch does not have to be an ideal switch. It will change the resonance frequency, q value and NF less. But this solution entails at least twice the number of similar tap circuits and more loops. FIG. 5 shows a UHF handheld antenna 111 and an amplifier 12. The antenna contains two loops 11 3, 114, a switch 115 and seven capacitors 116_121. Each loop contains a coil (abbreviated as Ll). A second loop 114 is added to the first loop 113 via the switch U5. Capacitors 117 and 118 are variable capacitance diodes (M § has been Cvar, variable capacitance diode). Including loop I], series circuit 123 of capacitor up 97098.doc -11-200522441 and varactor diode 118 is connected in parallel with varactor diode 117 and capacitor 116. A tap circuit 124 including four capacitors 116-119 connects the antenna 111 to the amplifier via the tuning capacitor 122. The diameter of the loop is 5 cm. Ll = 89 nH. Rr = M Ω at 575 MHz. At a frequency of 575 MHz, r10ss skin = 0.18 β.
Rr與f4成正比，而Rl〇ss與VF成正比。心八以與“八❿為兩 個變容二極體，其參數如下：Rr is directly proportional to f4, and R10ss is directly proportional to VF. Xin Ba Yi and "Ba Yi" are two varactor diodes with the following parameters:
Cvar變化範圍： 2 pF 至 20 pF 〇Cvar range: 2 pF to 20 pF
Rseries變化範圍： 0·3 Ω 至 0.6 Ω。 加入龟谷态120(間§己為Cb)以減小變容二極體cVAR之串聯電 容。Cb=0.4 pF。 加入電容器121(簡記為Ca)以減小電容CvAR。Ca=4 pF。 R、L、C串聯共振器之串聯電阻之變化範圍為116 β (Cmin)至〇_47 Q(Cmax)。電容變化範圍為〇/75奸至167 pF ° 增加開關115以獲得最高頻率範圍。 當開關115斷開時，頻率範圍為41〇百萬赫至615百萬赫。 當該開關開啟時，頻率範圍為580百萬赫至87〇百萬赫。 圖6A、6B顯示運用上述兩個頻率範圍所推得之雜訊因 數。因此，對於UHF頻帶，NF之變化範圍為4·5犯至1 dB 〇 圖7A與7B顯示運用Q所推得之頻寬。 因此，對於UHF頻帶，頻寬變化範圍為3百萬赫至“百 萬赫。要提高較低間隔，需要一較高之以，其意味著一更 97098.doc 12 200522441 大之衣路直徑。對於第二間隔，Rr使頻寬增大。為使其降 低’需要減小Rr，不幸地是，這樣會增大NF。 如果考慮環路之寄生電容Cp=〇 4 pF，則圖5令所述系統 之調諧範圍為370百萬赫至606百萬赫。需並聯插入兩個其 他相同尺寸之環路，以上升至7〇〇百萬赫。當輻射電阻不 文％, NF與頻寬曲線保持相同。另一解決方案為採用一較 小之直控，可增大fmax，但會使Nf更高。 【圖式簡單說明】 圖1係用於解釋本發明原理之調諧環路天線之系統方塊 圖； 圖2係圖1所示天線之等效電路之示意圖； 圖3係說明對於不同環路直徑，雜訊因數隨頻率之變化 曲線； 圖4A係一天線之具體實施例，其擁有兩個環路及一並聯 插入之電容器； 圖4B係一天線之具體實施例，其以電容器進行精細調 諧’以增加數個並聯環路進行離散階調諧； 圖4C係一天線之具體實施例，其擁有一環路及一並聯插 入之L C關聯電路； 圖4D係圖4C所示天線之等效電路之示意圖； 圖4E係一擁有兩個串聯插入之電容器之天線的具體實施 例； 圖4F係一擁有若干可調諧電容器之天線的具體實施例； 圖4G係一天線系統之具體實施例，其擁有兩個獨立天 97098.doc -13- 200522441 線’分別涵蓋一接收頻帶之不同頻段； 圖5係UHF手持天線之較佳具體實施例； 圖6八係顯示雜訊因數隨直到600百萬赫之UHF頻帶變化 之曲線； 圖6B係顯示雜訊因數隨高於6〇〇百萬赫之uhf頻帶變化 之曲線； 圖7A係一顯示由q導出之頻寬隨直到6〇〇百萬赫之頻率 變化之曲線；及 圖7B係一顯示由Q導出之頻寬隨高於600百萬赫之頻率 變化之曲線。 【主要元件符號說明】 1 環路天線 2 環路 3 電容器CC〇) 4 輻射電阻（Rr) 5 直徑 6 放大器 7 輸出 8 線圈（L〇) 9 才貝耗電阻（Rloss skin) 10 電流源 11 電磁場（Hi) 12 電壓CVi：) 13 輸出 97098.doc 200522441 21 曲線（3釐米） 22 曲線（4釐米） 23 曲線（5釐米） 24 區間 31 天線 32 帶有L!之環路 33 帶有L2之環路 34 電容器（c2) 41 天線 42 電容器 43 帶有之環路 44 帶有L2之環路 45 帶有L3之環路 51 天線 52 帶有L〇之環路 53 LC電路 54 電容器（c3) 55 線圈L4 60 天線組態 61 天線 62 放大器 63 環路 64 調諧電容器（ca) 65 調諧電容器（cb) 97098.doc -15- 200522441 66 調諧電容器（Cc) 67 並聯電路 68 分接頭電路 71 天線 72 放大器 73 環路 74 調諧電容器（ca) 75 調諧電容器（cb) 76 調諧電容器（cb) 77 調諧電容器（ca) 78 調諧電容器（Cc) 79 調諧電容器（Cc) 80 分接頭電路 81 分接頭電路 91 天線系統 92 天線組態（第二） 93 天線 94 放大器 95 環路（並聯） 96 環路（並聯） 97 分接頭電路 98 調諧電容器 99 調諧電容器 100 調諧電容器 97098.doc -16- 200522441 111 UHF手持天線 112 放大器 113 帶有川之環路 114 帶有之環路 115 開關 116 電容器 117 變容二極體 118 變容二極體 119 電容器 120 電容器 121 電容器 122 電容器 123 串聯電路 124 分接頭電路 97098.doc 17-Rseries range: 0 · 3 Ω to 0.6 Ω. Turtle valley state 120 (Cb) has been added to reduce the series capacitance of varactor cVAR. Cb = 0.4 pF. A capacitor 121 (abbreviated as Ca) is added to reduce the capacitance CvAR. Ca = 4 pF. The series resistance of R, L, and C series resonators varies from 116 β (Cmin) to 0_47 Q (Cmax). Capacitance changes range from 0/75 to 167 pF ° Increase switch 115 for the highest frequency range. When the switch 115 is turned off, the frequency ranges from 41 MHz to 615 MHz. When the switch is turned on, the frequency ranges from 580 MHz to 87 million MHz. Figures 6A and 6B show the noise factors derived from the two frequency ranges. Therefore, for the UHF band, the range of NF varies from 4.5 to 1 dB. Figures 7A and 7B show the bandwidth obtained by using Q. Therefore, for the UHF band, the bandwidth varies from 3 megahertz to "megahertz. To increase the lower interval, a higher one is needed, which means a larger diameter of 97098.doc 12 200522441. For the second interval, Rr increases the bandwidth. In order to reduce it, it is necessary to reduce Rr, which unfortunately increases NF. If the parasitic capacitance of the loop Cp = 〇4 pF is considered, Figure 5 The tuning range of this system is 370 megahertz to 606 megahertz. Two other loops of the same size need to be inserted in parallel to rise to 700 megahertz. When the radiation resistance is unknown, the NF and bandwidth curves Keep the same. Another solution is to use a smaller direct control, which can increase fmax, but it will make Nf higher. [Brief description of the figure] Figure 1 is a system for tuning the loop antenna to explain the principle of the present invention. Block diagram; Figure 2 is a schematic diagram of the equivalent circuit of the antenna shown in Figure 1; Figure 3 is a graph showing the variation of noise factor with frequency for different loop diameters; Figure 4A is a specific embodiment of an antenna, which has two A loop and a capacitor inserted in parallel; Figure 4B shows an antenna This embodiment uses fine tuning with capacitors to increase the number of parallel loops for discrete-order tuning. Figure 4C is a specific embodiment of an antenna, which has a loop and an LC-associated circuit inserted in parallel; Figure 4D is a diagram Schematic diagram of the equivalent circuit of the antenna shown in 4C; Figure 4E is a specific embodiment of an antenna having two capacitors inserted in series; Figure 4F is a specific embodiment of an antenna having a number of tunable capacitors; Figure 4G is an antenna A specific embodiment of the system, which has two independent days 97098.doc -13- 200522441 Lines respectively cover different frequency bands of a receiving frequency band; Figure 5 is a preferred embodiment of a UHF handheld antenna; Figure 6 and 8 show noise Figure 6B is a graph showing the variation of the noise factor with the uhf band above 600 MHz; Figure 7A is a graph showing the bandwidth derived from q as a function of up to 600 MHz The frequency change curve of 600 MHz; and FIG. 7B is a curve showing the frequency change derived from Q with the frequency higher than 600 MHz. [Description of the main component symbols] 1 Loop antenna 2 Circuit 3 capacitor CC〇) 4 Radiation resistance (Rr) 5 Diameter 6 Amplifier 7 Output 8 Coil (L〇) 9 Rloss skin 10 Current source 11 Electromagnetic field (Hi) 12 Voltage CVi :) 13 Output 97098. doc 200522441 21 curve (3 cm) 22 curve (4 cm) 23 curve (5 cm) 24 interval 31 antenna 32 loop with L! 33 loop with L2 34 capacitor (c2) 41 antenna 42 capacitor 43 band There loop 44 Loop L2 45 Loop L3 51 Antenna 52 Loop L0 53 LC circuit 54 Capacitor (c3) 55 Coil L4 60 Antenna configuration 61 Antenna 62 Amplifier 63 Loop 64 Tuning capacitor (ca) 65 Tuning capacitor (cb) 97098.doc -15- 200522441 66 Tuning capacitor (Cc) 67 Parallel circuit 68 Tap circuit 71 Antenna 72 Amplifier 73 Loop 74 Tuning capacitor (ca) 75 Tuning capacitor (cb) ) 76 Tuning capacitor (cb) 77 Tuning capacitor (ca) 78 Tuning capacitor (Cc) 79 Tuning capacitor (Cc) 80 Tap circuit 81 Tap circuit 91 Antenna system 92 Antenna configuration ( Second) 93 antenna 94 amplifier 95 loop (parallel) 96 loop (parallel) 97 tap circuit 98 tuning capacitor 99 tuning capacitor 100 tuning capacitor 97098.doc -16- 200522441 111 UHF handheld antenna 112 amplifier 113 with a ring of Sichuan Circuit 114 with loop 115 switch 116 capacitor 117 variable capacitance diode 118 variable capacitance diode 119 capacitor 120 capacitor 121 capacitor 122 capacitor 123 series circuit 124 tap circuit 97098.doc 17-