FI118750B - Mast Amplifier unit - Google Patents

Description

»118750

Mast amplifier unit

The invention relates to an amplifier unit belonging to a two-way radio system located on an antenna mast. The amplifier unit is particularly suitable for use in base stations of cellular networks.

5 In a bidirectional system, transmission and reception may have a common antenna, but processing signals in opposite directions will of course require their own transmission path. On the receiving side, when leaving the antenna of the first amplifier, it is advisable to be as close to the antenna as possible because the reception signal is low level and would be further attenuated by a long intermediate cable. 10 In this case, the signal-to-interference ratio at the input of the amplifier would be worse compared to the amplifier being located at the antenna. As a result, the transmission branch forks, viewed from the antenna, near the transmit and receive branch, the latter having a low-noise amplifier. When the antenna is close to the receiver and transmitter, the transmission paths naturally remain separate for them. While the antenna at the top of the mast is relatively far from the transmitter and receiver, separate intermediate cables for transmit and receive cause a significant cost increase for the equipment. For this reason, transmission and reception transmission paths tend to be reconnected after the amplifier on the antenna mast so that only one intermediate cable comes down from the mast.

• V; Figure 1 is a block diagram of a typical masthead • * amplifier (MHA). In this example, it consists of two radiators, two transmission branches, and *. ♦. two reception branches. There are two such units to implement diversity, a long-known means of improving the reliability of a radio connection.

: * y The first transmission branch has a band-pass type first • · · 25 transmission filter 120 which strongly suppresses the out-of-band frequency components, thus preventing e.g. leaking the amplified reception signal to the input of the reception branch. The first receive branch has a first receive input filter 130, a first low noise amplifier 140, or a first receive 30 output filter 150, in the forward direction of the signal. These receive filters are band pass type and strongly suppress the receive band. external frequency components • · '*: · * thus purifying the received signal and protecting the LNA. The input of the input input filter 130 and the output of the transmission filter 120 are connected by a common line an - *: ··. "Radiator" as used herein and in the claims means an antenna element for both transmission and reception. The output of the receive output filter 150 and the input 118750 2 of the transmit filter 120 are connected and connected to the first DC separator 110. This is further connected to a common first intermediate cable 160 which is connected at its lower end to the first base station block BT1. Through DC separator 110, the operating voltage Vsi of the first receiving branch is obtained.

5 The second receiving branch is similar to the first receiving branch. Thereby, there is a second low-noise amplifier 240 between the second receive input filter 230 and the second receive output filter 250. In the same way as the first transmission filter 220 is adjacent to the first reception branch, the second transmission filter 220 forming the second transmission branch is adjacent to the second reception branch 10. This parallel connection is connected by a common wire to the other radiator RD2 of the antenna and at one end of the base station from the second DC disconnector 210 to the second intermediate cable 260. This is connected at its lower end to the second base station block BT2.

Figure 1 shows a first transmission signal TX1 propagated to a first radiator RD1 through a first transmission filter 120 and a first reception signal RX1 propagating from a first radiator to a receiving branch. Correspondingly, the second transmission signal TX2 propagated to the second radiator RD2 through the second transmission filter 220 and the second reception signal RX2 propagating from the second radiator to the second receiving branch are indicated.

Figure 2 shows an example of a physical implementation of the known mast amplifier unit of Figure 1 with respect to its filters. The structure includes a BDY body and a · · · * upper part which together form a conductive housing. In Figure 2, the structure is shown open with the filters visible from above. At the other end of the first casing: * At the other end there is a coaxial first base station connector * · 25 BC1, from which the first transmit and receive branch of the amplifier unit MHA is connected via an intermediate cable to the first base station block BT1. At the other opposite end of the first end of the housing, there is a coaxial second base station connector BC2, from which the second transmit and receive branch of the amplifier unit is coupled to the second base station block BT2 by an intermediate cable. At one end of the second end of the housing there is a ♦ ·) 30 coaxial first antenna connector RC1, from which the first transmit and receive branch of the amplifier unit is connected by an antenna cable to the first radiator '·; ** RD1; the receiving branch is connected by a second an -.... j tennis cable to another radiator RD2.

118750 3

The body BDY includes partitions which divide the interior of the filter compartment so that each filter has its own separate filter cavity. The cavity of the first transmission filter 120 extends from the first end to the second end of the housing on the side of the first side wall of the housing. The first base station connector BC1 and the first 5 antenna connector RC1 are located at the opposite ends of the transmit filter 120. Similarly, the cavity of the second transmission filter 220 extends from one end of the housing to the other end of the second side wall of the housing, and the second base station connector BC2 and the other antenna connector RC2 are at opposite ends of the second transmission filter 220. The first receive input filter 130 is adjacent to the first transmit transmitter 120 on the second end of the housing, and the first receive output filter 150 is adjacent to the first transmit filter on the first end of the housing. A second receive input filter 230 is adjacent to a second transmit filter 220 on one side of the housing, and a second receive output filter 250 is adjacent to a second transmit filter on the first housing 15 side of the housing.

The filters are resonator filters, each of the resonators being a quarter wave type with its inner conductor lower end connected to the bottom of the BDY body and the upper end up in the air. In this example, each of the transmission filters 120, 220 has four internal conductors, such as an inner conductor 20 222 closest to the inlet end of the second transmission filter 220, and thus four resonators. Each of the receive input filters 130, 230 in this example has six resonators, respectively, and each of the receive output filters 150, 250 has four resonators, respectively. In addition, the • • · V! both the inlet and outlet ends of the filter also have in this example a coupling element from the bottom of the housing / l · upwards, such as the inlet of the first transmission filter 120; 25 coupling means 121. This coupling member and the first transmitting means

·· «I

. . ·. • · # V. '.' in the wall between the filter and the first receive output filter 150. via the van connection port, the amplified first receive signal * ··· 'RX10Ut is propagated to the same connector BC1 and the intermediate cable through which the first transmit signal TX1 enters the mast amplifier unit. The first transmission signal TX1 continues to: * ·· 30 antennas via said connector RC1. Through this connector, the antenna becomes the first receive signal RX1, which propagates through the coupling means at the output end of the first transmit filter 120 and the first receiving input filter in the wall between the first transmit filter and the first receive input filter 130.

* * »· 35 Similarly, the amplified second receive signal RX20Ut proceeds via a field opening in the wall between the second receiver filter 250 and the second transmit filter 220, and the connecting element 221 at the inlet end of the second transmit filter to the same connector BC2 and intermediate cable. the TX2 transmission signal is supplied to the mast amplifier unit. The second transmission signal TX2 continues to the antenna via said connector RC2. Through this connector, the antenna receives a second receiving signal RX2 which propagates through a coupling member at the output end of the second transmission filter 220 and a second receiving input filter in the wall opening between the second transmission filter and the second reception input filter 230.

Fig. 3 is a view of the mast amplifier unit of Fig. 2 as seen from the side 220 of the second transmission filter 10 and with the side wall cut away. From the drawing it appears that the mast amplifier unit MHA has, in addition to the filter section shown in Figure 2, another section ELP having a PCB. This circuit board contains the electronics of the unit, which is why this second compartment is referred to herein as the electronics compartment. The filter compartment shows the filter housing body BDY, the intermediate cover 15 CEI, the inner conductors and switching means of the second transmission filter 220, and the parts 211, 212, 213 of the DC separator 210 mentioned in the description of Fig. 1. The circuit board PCB is mounted above the intermediate cover CEI. The circuit board has a conductive protective cover COV, which is also shown in Figure 3, cut out from the side. The body BDY and the COV housing cover together form the entire housing of the mast amplifier unit.

20 The core of the electronics of the MHA unit is naturally the LNAs. In Fig. 3, a second LNA 240 is shown in FIG. 3. This input is coupled via a lead-through of the intermediate cover CEI to the coupling member at the output end of the second receiving input filter 230 shown in FIGS. The output of the LNA 240, in turn, is coupled via an intermediate cover bushing to a coupling member at the inlet end of the second receiving output filter 250.

** Y 25 In the electronics department, ELP also has eg. lightning protection 214, which is a discharge component between the electrical · V supply voltage VS2 and ground. The operating voltage in the base station block BT2 is connected to the middle conductor 260 of the intermediate cable. This center conductor is connected to the tubular separator 211 shown in Figures 2 and 3 at connector BC2 of the MHA unit, from which the supply voltage 30 213 is applied to the lightning protection 214 and further to the electronic circuits. Inside the separator 211 of the DC separator is a switching conductor 212 which is connected at one end to a switching means at the inlet end of the second transmission filter • φ · 221. There is only capacitive impedance between the separator 211 and the switching conductor 212. via coupling member 221 Y \ 35. At unit operating frequencies, this impedance is negated so that the transmission signal TX2 can propagate to the transmission filter 220. The input line 213 is 118750 5 quarters wavelengths, so that the radio frequency signals reflected from the circuit board are transmitted to the DC isolator.

A disadvantage of the mast amplifier units of Figures 2 and 3 is that they are relatively large and heavy. This represents a significant cost in production.

The object of the invention is to reduce said disadvantage associated with the prior art. The mast amplifier unit according to the invention is characterized in what is disclosed in the independent claim 1. Certain preferred embodiments of the invention are set forth in the other claims.

The basic idea of the invention is as follows: A mast amplifier unit having a parallel receiving branch and a transmission branch consists of a physically overlapping filter section and an electronics section. The receive branch has a receive input filter, an LNA, and a receive output filter, and the transmit branch has a transmit filter. The receive input filter and the transmit filter are in the filter compartment and are implemented as relatively massive air insulated resonator filters to keep the noise figure of the receivers and transmitter losses low enough. Instead, the receive output filter in the invention is implemented in a relatively small size and is placed in the electronics department of the unit. In addition, the unit may have at least one receiving branch for diversity, so that this input filter is also in the filter section ** and the output filter in the electronics section.

• · • · · · ·

An advantage of the invention is that the size of the mast amplifier unit is significantly reduced compared to known units. This is because the reception output filter (s) do not require space in the filter compartment of the unit, thereby reducing the cross-sectional area of this unit and thus the size of the unit. For the same reason, the amount of material used in the unit • · ·. ** ·, 25 L decreases, which means a reduction in production costs. A further advantage of the invention is that it enables the use of various filter techniques in the manufacture of reception output filters.

• · • ·· * * ·

The invention will now be described in detail. In the description, reference is made to the accompanying drawings in which: • Fig. 1 is a block diagram of an example of a mast amplifier unit, Fig. 2 illustrates an example of a physical implementation of a known mast amplifier unit for its filters, 118750 6 Fig. 3 is a side elevation and side wall sectional view of the mast amplifier unit of Fig. 2, Fig. 4 is a block diagram of the principle of the invention, Fig. 5 illustrates a physical implementation of the filter-5 compartment of the mast amplifier unit Fig. 7 is a sectional view of a second example of a rigid arrangement in accordance with the invention in a mast amplifier unit, 10 Figs. 8a illustrating a third example of an arrangement of the invention in a mast amplifier unit; Fig. 10 shows a fifth example of an arrangement according to the invention in a mast-15 amplifier unit, and Fig. 11 shows another example of a physical implementation of a mast section of the mast amplifier unit according to the invention: V.

Figures 1-3 were already described with reference to the prior art.

Figure 4 illustrates the principle of the invention. It has a mast amplifier unit MHA, which is a block diagram similar to that shown in Figure 1. The unit thus has two ··· parts, each with a transmit and receive branch in parallel. The first transmission branch has a first transmission filter 420, and the first transmission branch has a first LNA 440 between a first receive filter ···, a loss filter 430 and a first receive output filter 450. The input of the first * * *** 25 reception input filter and the output of the first transmission filter are connected via a common line V to the first radiator RD1 of the antenna ANT. The output of the first receive output filter and the input of the first transmit filter are combined and \ # connected to the first DC separator 410. This is further connected to the first intermediate cable 460, which is connected at its lower end to the first base station. Similarly, one transmission branch has a second transmission filter 520, and a second reception branch has a second LNA 540 between a second receive input filter 118750 and a second receive output filter 550. The input of the second reception input filter and the output of the second transmission filter are connected by a common cable to the second radiator RD2 of the antenna ANT. The output of the second receive output filter and the input of the second transmit filter are connected and connected to the second DC separator 510. This is further connected to a second intermediate cable 560 which is connected at its lower end to the second base station block BT2.

Figure 4 shows a first 440 and a second 540 LNA, a first 450 and a second 550 output filter, and a portion of the first 410 and second 510 DC separators separated by a dashed line into its own unit ELP. This unit contains the MHA electronics circuits of 10 complete mast amplifier units and physically separate the electronics section. It is inventive here that the said receiving output filters are also in the electronics section ELP, instead of being physically present in the filter section with other filters as in Figure 2. The main advantage of the solution is shown in Figure 5 below.

By contrast to Figure 4, the mast amplifier unit may lack a second transmission branch or have only one transmission branch and one reception branch connected in parallel.

Figure 5 shows an example of a physical implementation of the filter section of a mast amplifier unit according to the invention. The structure is shown open with the filters visible from above, as in Fig. 2. The difference between Fig. 2 and the above is that the first and second receive output filters are missing. Otherwise, the structure is as shown in Figure 2. Thus, there is a first transmission filter 420 on the first side wall of the BDY body and a second transmission filter 520 on the side side of the second side wall, and a first reception input filter between these two filters. The cavities of all four filters extend to .i: 25 watts. from the first end of the body to the second end. The first end has terminals BC1, BC2 for the base station blocks and the second end has the coaxial terminals RC1, RC2 for the radiators, as shown in Figure 2.

··· **: ** When comparing the structure of Figure 5 with the known structure of ··· in Figure 2, it is found that the body BDY can be shortened in the direction of the side walls by the length of the side outlet filters. This shortening ·· *, for example, is in practice 25%. If the other dimensions of the amplifier unit are maintained · "*, the volume of the unit will be reduced proportionally. This results in considerable space and material savings.

«T • · · • ·· • e 118750 8

Fig. 6 is a mast amplifier unit corresponding to Fig. 5, seen from the side of the second transmission filter 520, and cut away from the side wall. The housing of the mast amplifier unit consists of a body BDY and a COV housing over it, with an intermediate cover 5 CEI separating the filter and electronics compartments, as shown in Figure 3. The electronics compartment ELP shows the PCB PCB and the filter compartment for the The parts 511, 512, 513 included in the DC separator 510, as in Fig. 3. The DC separator is similar to that described in Fig. 3. The difference with Fig. 3 is that according to the invention, the circuit board now includes a first (not shown) and a second 10 550 receiving output filters. The output of the filter 550 is capacitively coupled to the circuit board PCB to the supply conductor 513, which, on the other hand, supplies the electronics operating voltage to the circuit board. Through the supply line 513, the transmission path of the second reception signal continues to the terminal BC2 and further to the second base station block.

The output output filters in this example are, for example, piece components made on a ceramic substrate 15. Compared to the air insulated resonator filters of Figure 3, the attenuation naturally increases with a change of, for example, 0.3 dB. However, the front-end noise figure of the receiver can still be easily kept below the specified maximum. This is helped by the fact that the received output filter passes an already amplified signal. On the input side of the LNA, the damping premium would be a more stable-20 vamp.

: ***: Figure 7 shows another example of an arrangement according to the invention. The drawing shows only the PCB in the electronics section of the mast amplifier unit. Here again, only the part with one of the two reception output filters is shown. The receive output filter 750 in this case is implemented in the circuit board PCB conductor 25 violet. The filter is a comb-type resonator filter with five parallel finger strips, such as strip 755, on the top surface of the circuit substrate. The other ends of the strips are connected to the ground plane on the GND circuit board, and their corresponding resonators are four. are the switching strips at both the inlet and outlet of the filter. The filter 750 includes a function -. * ··. 30 typically also a conductive cover above the circuit board and a conductive] · * intermediate cover which forms the outer conductor of the resonators and is thus required. The signal ground is amplified at the filter with a metal body 759 extending from the circuit board to the aforementioned conductive sheath, thereby catching a more uniform ground potential at the base of the finger strips, the inner conductors, of the structure. o n connected to the LNA output by the conductor strip 702, and the filter output 118750 9 is capacitively coupled to the output conductor 715 which, after the circuit board passage, continues as a downstream supply wire from the circuit board to the center conductor of the connector to the base station. The supply cable supplies the circuit board with the required operating voltage for the electronics, as previously described. The aforementioned capacitive coupling 5 is required to prevent the operating voltage from shorting to ground through the GND filter. Also shown in the figure is a lightning protection 714 between the supply line and the ground.

The second receive output filter of the mast amplifier unit is similar to the one described above and is located in another area of the PCB.

Figures 8a and 8b show a third example of an arrangement according to the invention. 10 They show the part of the PCB of the mast amplifier unit which has one of the two reception output filters. In Fig. 8a, the structure is shown with the upper parts of the circuit board removed from the normal direction. It shows, in addition to the circuit board, the periphery of the intermediate cover CEI, which is perpendicular to the level of the intermediate housing, separating the actual filter compartment and the electronics compartment. The output output filter 850 is implemented on a PCB PCB as a comb-type resonator filter, as in Figure 7. The difference with Figure 7 is that the dielectric substrate of the circuit board is machined at the filter so that protrusions in the form of filter inner wires are formed on the substrate. These projections are coated on all sides with conductive material to form the inner conductors 855. Thus, the dielectric losses caused by the circuit board are significantly lower than in the structure shown in Fig. 7.

M · • · · · I ·. *. Fig. 8b is a cross-sectional view of the structure X-X adjacent to one of the inner conductors 855, *, showing the respective projection of the substrate from the side. The narrow side surface of the projection is covered with a guide. A small part of the metal structure shows the filter housing run-:.! : gosta BDY, part COV cover part, CEI part cover and additional cover LID under cover. The outer conductor of the resonators is for the most part comprised of an intermediate cover CEI with edges and an additional cover LID. In principle, a COV shield could function as part of an outer conductor without an additional field. However, the gal- between it and the body BDY: ·. • the contact is weak due to the intermediate seal, which • • makes use of a solidly grounded auxiliary field. The filter cavity inside the outer conductor **, ·· * 30 is partially enclosed by a small metal beam 859 that extends from the circuit board to the bottom of the inner conductors: V: to reach the additional cover LID. At the same time, this bar amplifies the signal ground of the filter at the base of the internal conductors. The additional cover could also be bent to · · ·, ground on, and screwed to the circuit board so that the metal bar would be part of the · · · · · ··· cover.

• · »» · «M • · 118750 10

Figure 9 shows a fourth example of an arrangement according to the invention. In the drawing there is a mast amplifier unit corresponding to figure 5 as seen from the side of the second transmission filter 520 and the side wall cut off. The mast amplifier unit housing consists of a filter compartment body BDY and a COV cover 5 over it. Between these are the intermediate cover CEI separating the filter and electronics compartments, as shown in Figure 6, and the securely grounded additional cover LID just below the protective cover. The reception output filters in this case are implemented as air insulated resonator filters in the electronics department ELP. Fig. 9 shows a second receive output filter 950, which in this example has in succession five five-way inner conductors, such as the first 951 and fifth 955 inner conductors, which are connected at their lower end to the intermediate CEI and thus to the signal ground. At the top of the inner conductors is an expansion board, such as conductor board 959, as an extension. In this way, quarter-wave resonators 15 can be accommodated in a lower space than without guide plates. The inner wires in this example are the same piece as the intermediate cover. The inner conductor with its extension portions may also form a single piece which is conductively fixed to the intermediate cover.

The output of the second LNA of the mast amplifier unit is coupled via the switching conductor 903 to the first inner conductor 951. The output conductor 913 of the filter 950 is capacitively connected to the fifth inner conductor 955, particularly its conductor board. A capacitive connection is required to prevent the operating voltage from short-circuiting through the internal * · * * wires of the filter 950. The output conductor 913 extends to the center conductor of the terminal BC2 to the base station and is also the supply conductor through which the required operating voltage of the electronics is supplied.

• * t

The receiving output filter 950 has its own cavity formed in the electronics compartment * ··· * ELP by a conductive partition which is a protrusion of the intermediate cover CEI. The PCB PCB is located almost entirely outside this cavity in the electronics department.

Fig. 10 shows a fifth example of an arrangement according to the invention in a mast amplifier unit. The unit is drawn from the side with a side wall cut out as in Figures 6 and 9. The difference with these is that the electronics section ELP is now below the filter section. This means that the bottom of the unit body forms here *. in the example, the CEI separator cover separating the electronics and filter compartments. The electronics-carrying circuit board PCB is affixed to the underside of said base and is housed in a cavity 35 enclosed by a COV, the conductive sheath at its lowest level in the structure. The circuit board has e.g. at least one receiving output filter A50. The filter cavities are closed by the conductive auxiliary lid LD2 above the inner conductors. Above this, in this example, another protective cover is provided to protect the resonators of the resonators attached to the CV2 auxiliary cover LD2.

Figure 11 illustrates another example of a physical implementation of a duo section of a mast amplifier unit according to the invention. 2 and 5. It has a first transmission filter A20, a first receive filter A30, and a second receive filter B30 as shown in Figure 5. The only difference with the structure shown in Figure 5 is that the second transmit filter is missing. It is missing from the entire mast amplifier unit, so here is a 10 diversity only reception. The mast amplifier unit may also have only one transmission branch and one reception branch, leaving another structure of the reception filter A30 in the structure shown in Fig. 5.

The "lower", "upper", and "on" attributes in this specification and claims refer to the position of the mast amplifier unit with its housing bottom and shield 15 horizontal, and the inner wires of the filter section resonators above. Of course, the operating position of the unit can be any. The cross-sectional area of a unit means its area when viewed from above.

The mast amplifier unit according to the invention has been described above. Naturally, the structure may differ in its details from the embodiments shown. The inventive concept of e ·: V 20 can be applied in different ways within the limits set forth in the independent claim 1.

«M

«··· • · • ♦ * • · · · · · 9 ··· • e · • * * · ♦ ·· ··· ♦

• M

* • e »• · * · * • • • • • • • • • • • • • • • • • • • • • • • • • · · · · · ·

Claims (12)

118750 A mast amplifier unit (MHA) having at least a parallel receiving branch and a transmission branch connected at one end to a first base station connector (BC1) and a second end to a first antenna connector (RC1), wherein the receiving branch comprises a receiving input filter (430); An LNA (440) and a receive output filter (450) and a transmission branch having a transmission filter (420) physically comprising overlaps, a spacer (CEI) separated by a filter compartment and an electronics compartment (ELP) in a housing comprising a body (BDY) and at least one ) and having a casing cross-sectional area 10 defined by a cross sectional area of the filter section comprising at least said receiving input filter (430) and the transmission filter (420) implemented as a body (BDY) relatively massive air-insulated resonator filters to keep receiver noise and transmitter losses small and comprising an electronic circuit board (PCB), characterized in that it has a receive-output filter (450; 550; 750; 850; 950) is located in said electronics department (ELP) to reduce and lighten the unit (MHA). A mast amplifier unit according to claim 1, further comprising at least one receiving branch connected to one base station connector (BC2) and one antenna connector (RC2) at one end and having a second receiving branch in order in order to provide diversity. ·: An input input filter (530), one an LNA (540), and another receive output filter (550),: T: and said filter section also comprises a second receive input filter implemented as a · ··· relatively massive air insulated resonator filter · ·. to maintain a low noise figure, characterized in that its second "V 25 receiving output filter (550) is also located in said electronics compartment 1" (ELP) to reduce and lighten the unit (MHA). • · • · ··· The mast amplifier unit according to claim 2, further comprising a second transmission branch adjacent to the second receiving branch for transmission diversity] ·· ♦. characterized in that the second transmission branch comprises a second transmission filter (520) and this filter is located in said filter compartment as a relatively massive air insulated resonator filter to keep the transmitter losses small. • • e ·· · • V The mast amplifier unit according to claim 1, wherein the operating voltage (Vsi; VS2) required by the receiving branch is provided from a base station 35 to the center conductor (511) of said base station connector (BC1; BC2) and the associated feed 118750 work conductor (513; 813). ), characterized in that the output of the receiving output filter (550; 750; 850) is capacitively coupled to said supply conductor which thus acts as the output conductor of the receiving branch. A mast amplifier unit according to claim 1, characterized in that said receiving output filter (550) is a ceramic resonator filter mounted on said circuit board (PCB). A mast amplifier unit according to claim 1, characterized in that said receiving output filter (750; 850) is a comb-type resonator filter with its inner conductors (755; 855) being the conductor cover of the substrate of the printed circuit board (PCB) and (GND). A mast amplifier unit according to claim 6, characterized in that the substrate of the circuit board (PCB) has successive finger-like projections and said conductor coating covers these projections on each side to form the internal conductors (855) of the receiving output filter (850). The mast amplifier unit according to claim 6, further comprising a spacer cover (CEI) above the inner conductors of the receiving output filter and below the protective housing (COV), characterized in that the outer conductor of the resonators of the receiving output filter (850) comprises an intermediate part (CE) and an additional cover (LID), at least in part, and extending · · · · V 20 to the ground plane (GND) of the circuit board at the base of said internal wires through a metal beam: T: (759; 859) to amplify the signal ground of said filter. · * ♦ · * ·; A mast amplifier unit according to claim 1, characterized in that said reception output filter (950) is an air insulated resonator filter having successively parallel internal conductors (951, 955) connected to the lower end of said intermediate cover (CEI). ). A mast amplifier unit according to claim 9, characterized in that: • at the upper end of the inner conductors (951, 955) is a wiring board (959) to increase the electrical length of the resonators corresponding to the inner conductors and thus to reduce the output filters operating in the specified frequency range. * · · A mast amplifier unit according to claim 1, characterized in that: v. The electronics compartment is above the filter compartment. • · ·· ♦ ♦ »• · ··· 118750 A mast amplifier unit according to claim 1, characterized in that said electronics compartment is below the filter compartment, wherein the bottom of the filter compartment, i.e. the bottom of the body (BDY), is also said intermediate cover (CEI). 5 Patent claims